SYNC™

SynC · Editorial revision

Electrical Rooms

Revision8
EditedOct 19, 2026
StatusCurrent
Contents

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Current revision. This is editorial revision 8, the current text of this standard. Read it on the standard's page.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Remake batch 26: rewritten from scratch under the authoring cheatsheet with datasheet constraints; neighbors re-pointed to the new scope boundaries; the electrical code is now the adopted-electrical-code project fact

1 Scope

NOTE This standard governs the electrical room as a space: the envelope, the clearances, the entrances, the environment and the services that let the equipment inside it be installed, operated and maintained safely for the life of the building. Every item of equipment in the room has its own standard that assumes the room satisfies this one, so this standard never selects, rates or describes the equipment; it describes what the room owes the equipment. (1.1)
NOTE The engineer decides the room type, the basis for the working space depth beyond what the adopted electrical code requires, whether the working space is marked on the floor, whether piping foreign to the electrical installation is tolerated anywhere in the room, the door clear opening and the panic hardware and locking policy, the water protection at the door and on the floor, the heat-release basis and the heat rejection method, the temperature and humidity limits, the condition monitoring, the illumination level and its control, the emergency illumination source, the convenience receptacle provision, the housekeeping pad provision and the floor finish, the room ground bar, the signs on the door and the field verification performed. The number of entrances follows from the equipment rating, the fire-resistance rating follows from the code analysis, and the upper temperature limit follows from the equipment ratings; this standard records those rather than choosing them. (1.2)
NOTE Two bodies of code shape the room. Adopted Electrical CodeAdopted Electrical CodeParameterEach project supplies its own value.adopted-electrical-code fixes the working space, the dedicated electrical space, the entrances, the illumination and the control of access about the equipment as installed, in NFPA 70 110.26 for equipment rated 1000 V and below and in 110.31 through 110.34 for equipment rated over 1000 V. Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code fixes the fire-resistance rating of the enclosing construction, the occupancy, the structural support and the means of egress that apply to the room as a building element. Where the two overlap, the room satisfies both. (1.3)
NOTE The following are governed elsewhere and are outside this standard: (1.4)
  • the equipment inside the room, each item of which has its own standard (Low Voltage SwitchgearLow Voltage SwitchgearResolves to the current adopted revision.sync/low-voltage-switchgear, Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current adopted revision.sync/low-voltage-switchboards, PanelboardsPanelboardsResolves to the current adopted revision.sync/panelboards, Motor Control CentersMotor Control CentersResolves to the current adopted revision.sync/motor-control-centers, Low Voltage Dry Type TransformersLow-Voltage Dry-Type TransformersResolves to the current adopted revision.sync/low-voltage-dry-type-transformers, Automatic Transfer SwitchesAutomatic Transfer SwitchesResolves to the current adopted revision.sync/automatic-transfer-switches, Medium Voltage SwitchgearMedium Voltage SwitchgearResolves to the current adopted revision.sync/medium-voltage-switchgear, Medium Voltage TransformersMedium-Voltage Distribution TransformersResolves to the current adopted revision.sync/medium-voltage-transformers, Secondary Unit SubstationsSecondary Unit SubstationsResolves to the current adopted revision.sync/secondary-unit-substations, DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems, Uninterruptible Power Supply SystemsUninterruptible Power Supply SystemsResolves to the current adopted revision.sync/uninterruptible-power-supply-systems, GeneratorsEngine GeneratorsResolves to the current adopted revision.sync/generators, Generator Paralleling SwitchgearGenerator Paralleling SwitchgearResolves to the current adopted revision.sync/generator-paralleling-switchgear)
  • the hydrogen ventilation rate, the hydrogen detection, the eyewash and the spill containment of a battery room, which DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems and Battery Energy Storage SystemsBattery Energy Storage SystemsResolves to the current adopted revision.sync/battery-energy-storage-systems set and which this standard requires the room to accommodate
  • the vault a liquid-filled transformer requires indoors under NFPA 70 Article 450 Part III, which Medium Voltage TransformersMedium-Voltage Distribution TransformersResolves to the current adopted revision.sync/medium-voltage-transformers governs
  • telecommunications rooms, equipment rooms and entrance facilities and the pathways serving them (Telecommunications Rooms And PathwaysTelecommunications Rooms and PathwaysResolves to the current adopted revision.sync/telecommunications-rooms-and-pathways), and the telecommunications bonding backbone and ground bars (Telecommunications BondingTelecommunications Bonding and GroundingResolves to the current adopted revision.sync/telecommunications-bonding)
  • the housekeeping pad as a structure, its height, projection, thickness, reinforcement and anchorage (Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads)
  • the design number, construction and continuity of the rated walls, floors and ceilings (Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies, Gypsum Board AssembliesGypsum Board AssembliesResolves to the current adopted revision.sync/gypsum-board-assemblies, Unit MasonryUnit MasonryResolves to the current adopted revision.sync/unit-masonry) and the firestop systems at every penetration of them (FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping)
  • the doors, frames and finish hardware as products, including panic hardware, closers and locksets (Doors Frames And HardwareDoors, Frames, and HardwareResolves to the current adopted revision.sync/doors-frames-and-hardware, Door HardwareDoor HardwareResolves to the current adopted revision.sync/door-hardware), and the readers, controllers and door position switches of the access control system (Access Control SystemsAccess Control SystemsResolves to the current adopted revision.sync/access-control-systems)
  • the fans, louvers, dampers, ductwork, cooling units and heaters that condition the room (HVAC FansHVAC FansResolves to the current adopted revision.sync/hvac-fans, Louvers And DampersLouvers and DampersResolves to the current adopted revision.sync/louvers-and-dampers, HVAC DuctworkHVAC DuctworkResolves to the current adopted revision.sync/hvac-ductwork, Split System Air ConditionersSplit-System Air Conditioners and Heat PumpsResolves to the current adopted revision.sync/split-system-air-conditioners, Fan Coil UnitsFan-Coil UnitsResolves to the current adopted revision.sync/fan-coil-units, Computer Room Air ConditioningComputer Room Air Conditioning UnitsResolves to the current adopted revision.sync/computer-room-air-conditioning, Unit HeatersUnit HeatersResolves to the current adopted revision.sync/unit-heaters) and the building automation system that monitors it (Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system)
  • the sprinkler, pre-action and clean agent systems that protect the room (Wet Pipe Fire Sprinkler SystemsWet-Pipe Fire Sprinkler SystemsResolves to the current adopted revision.sync/wet-pipe-fire-sprinkler-systems, Pre Action And Deluge Sprinkler SystemsPre-Action and Deluge Sprinkler SystemsResolves to the current adopted revision.sync/pre-action-and-deluge-sprinkler-systems, Clean Agent Fire SuppressionClean Agent Fire Suppression SystemsResolves to the current adopted revision.sync/clean-agent-fire-suppression)
  • the luminaires, the emergency luminaires, the lighting control devices and the receptacles as products (Lighting FixturesInterior Lighting Fixtures (Luminaires)Resolves to the current adopted revision.sync/lighting-fixtures, Emergency And Egress LightingEmergency and Egress LightingResolves to the current adopted revision.sync/emergency-and-egress-lighting, Lighting ControlsLighting ControlsResolves to the current adopted revision.sync/lighting-controls, Wiring DevicesWiring DevicesResolves to the current adopted revision.sync/wiring-devices)
  • the nameplates, warning signs and arc-flash labels on the equipment (Equipment LabelingElectrical Equipment LabelsResolves to the current adopted revision.sync/equipment-labeling), the arc-flash study behind them (Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study), and the egress signage of the building (Signage And Egress MarkingsCode-Required Signage and Egress MarkingsResolves to the current adopted revision.sync/signage-and-egress-markings)
  • the grounding electrode system, the bonding of the ground bar and the sizing of every bonding conductor (Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding)
  • the raceways, cable trays and busway entering and leaving the room (Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit, BuswayBuswayResolves to the current adopted revision.sync/busway)
  • the seismic anchorage design of the equipment (Vibration Isolation And Seismic RestraintVibration Isolation and Seismic RestraintResolves to the current adopted revision.sync/vibration-isolation-and-seismic-restraint) and the facility's energized work program (Electrical Safety ProgramElectrical Safety ProgramResolves to the current adopted revision.sync/electrical-safety-program)
  • the total building commissioning program into which the field verification of this standard is folded (CommissioningTotal Building CommissioningResolves to the current adopted revision.sync/commissioning)
  • outdoor equipment yards, utility-owned substations and vaults, and information technology equipment rooms under NFPA 70 Article 645, which no SynC standard yet owns
NOTE Where one room houses both electrical and telecommunications equipment, this standard governs the electrical equipment, its working space and its dedicated electrical space, and Telecommunications Rooms And PathwaysTelecommunications Rooms and PathwaysResolves to the current adopted revision.sync/telecommunications-rooms-and-pathways governs the telecommunications equipment, its clearances and its backboards, and neither reduces the other's clearances. (1.5)
1.6 The location, the plan dimensions and the equipment arrangement of each electrical room shall be as indicated on the electrical plans.
1.7 Every electrical room shall comply with Adopted Electrical CodeAdopted Electrical CodeParameterEach project supplies its own value.adopted-electrical-code for the spaces about electrical equipment, and with Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code for its construction, its fire separation and its means of egress.
1.8 An electrical room shall contain no equipment other than the electrical equipment it is built for, the raceways and busway serving that equipment, and the mechanical and fire protection equipment that serves the room itself.

2 Referenced Standards

2.1 Construction and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where the contract documents, the Authority Having Jurisdiction, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
Standard Title
NFPA 70 National Electrical Code (Article 110, Parts II and III; 210.63; 450.21; 700.16)
NFPA 70E Standard for Electrical Safety in the Workplace
NFPA 101 Life Safety Code
NFPA 110 Standard for Emergency and Standby Power Systems (Chapter 7)
NFPA 80 Standard for Fire Doors and Other Opening Protectives
NFPA 13 Standard for the Installation of Sprinkler Systems
IBC International Building Code (Chapters 7 and 10)
29 CFR 1910.303 Occupational Safety and Health Standards, Electrical, General (working space about electric equipment)
IEEE C37.20.7 Guide for Testing Switchgear Rated Up to 52 kV for Internal Arcing Faults
ANSI Z535.4 Product Safety Signs and Labels
ASHRAE 90.1 Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings
IECC International Energy Conservation Code

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review before the walls of any electrical room are framed and before any door, hardware or sign for the room is ordered:
  • the electrical room coordination drawing prepared under the Coordination Drawing section, in plan and in elevation, showing every lineup from its reviewed shop drawings, the working space and the dedicated electrical space about each, the entrances, the door swings and clear openings, the housekeeping pads, the lighting, the receptacles, the ground bar, every raceway, busway, pipe and duct that enters or crosses the room, and the egress path from the working space
  • the room heat-release schedule prepared under the Room Environment section, listing every item of equipment in the room with its heat release at the heat-release basis selected in the datasheet
  • the door schedule for every electrical room door, giving the clear opening, the swing, the fire rating, the panic hardware and the locking provision
  • the illumination calculation for the working space of each room, showing the maintained illuminance at the working plane and the luminaire locations against the dedicated electrical space
  • the schedule and artwork of the signs on each room door
Action Submittalscheckbox
☑ Electrical room coordination drawing in plan and elevation
☑ Room heat-release schedule
☑ Electrical room door schedule
☑ Working space illumination calculation
☑ Room door sign schedule and artwork
3.1.2 The walls of an electrical room shall not be framed, and its doors, hardware and signs shall not be ordered, until the action submittals covering that room have been reviewed and returned.

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following with or before the action submittals:
  • the reviewed shop drawing of each item of equipment from which the coordination drawing takes its dimensions, its weight, its heat release and its ventilation clearances
  • the exhaust plenum and discharge detail of any arc-resistant switchgear in the room, as reviewed under the standard for that switchgear
  • the room ventilation or cooling calculation prepared by the trade responsible for it, showing that the room holds the temperature limits of the datasheet with every item of equipment at the heat-release basis and with outdoor air at Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum
  • the field verification plan for the room, naming the person who performs each verification and the instrument used
Informational Submittalscheckbox
☑ Reviewed equipment shop drawings used by the coordination drawing
☐ Arc-resistant switchgear exhaust plenum and discharge detail
☑ Room ventilation or cooling calculation
☑ Field verification plan

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before the equipment in the room is energized for other than testing:
  • the record coordination drawing of each room, revised to the as-built positions of the equipment, the pads, the doors, the luminaires, the receptacles, the ground bar and every foreign system in the room
  • the field verification report of each room, recording every measurement the Field Verification section requires with the date and the person who took it
  • the as-built door schedule and sign schedule for each room
  • the room heat-release schedule revised to the equipment actually installed
Closeout Submittalscheckbox
☑ Record coordination drawing
☑ Field verification report
☑ As-built door and sign schedules
☑ As-built room heat-release schedule

4 Quality Assurance

4.1 Coordination Responsibility

4.1.1 The electrical Contractor shall prepare the coordination drawing and shall hold a coordination meeting for each electrical room, attended by the General Contractor and by the mechanical, plumbing, fire protection, structural and architectural trades, before the walls of that room are framed.
4.1.2 The coordination meeting shall settle the working space and dedicated electrical space about each lineup, the routing of every pipe, duct and raceway that enters or crosses the room, the pad locations, the door swings, the louver and duct penetrations of the rated enclosure and the egress path, and its minutes shall be issued to every attending trade.
4.1.3 A conflict found at the coordination meeting shall be resolved before the walls are framed, and where no other resolution exists the working space, the dedicated electrical space and the entrances required by Adopted Electrical CodeAdopted Electrical CodeParameterEach project supplies its own value.adopted-electrical-code shall govern, because they are code minimums while the routing of other trades is adjustable.
NOTE Every trade that penetrates or crosses an electrical room is a candidate to violate a clearance that only the electrical trade is measured against, and the clearances cannot be bought back after the slab is poured and the duct is hung. A coordination drawing that every trade has reviewed before framing is the one instrument that puts the clearance in front of the trade that would otherwise occupy it. (4.1.4)

4.2 Authority Having Jurisdiction Inspection

4.2.1 The working space, the dedicated electrical space, the entrances and the illumination of each room shall be left open to inspection by the Authority Having Jurisdiction after the equipment is set and before any ceiling, finish or foreign system conceals them.
4.2.2 The Contractor shall not conceal a rated wall, floor or ceiling of the room until the inspection of the assembly and of its firestopping required under Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies and FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping has been completed and released.

4.3 Qualified Persons

4.3.1 Access to an electrical room shall be limited to qualified persons as Adopted Electrical CodeAdopted Electrical CodeParameterEach project supplies its own value.adopted-electrical-code and NFPA 70E define them and to the persons the Owner authorizes in writing, and the room door shall be kept locked when no qualified person is in the room.

5 Room Type and Location

5.1 The type of space this standard is applied to shall be as indicated in the datasheet.
Room Typeselect
Dedicated electrical room
Electrical closet
Electrical equipment area within a mechanical or other equipment room
NOTE A dedicated electrical room is enclosed by its own walls and door and holds nothing but electrical equipment, so its working space, its dedicated electrical space and its environment are under the control of one trade, at the cost of floor area and of a separate ventilation or cooling provision. An electrical closet is the small room, usually serving one floor, that holds a panelboard, a transformer and a few disconnects behind a single door; it buys the least floor area and leaves the equipment to reject its losses into the corridor air or a transfer grille, which limits how much heat the closet can hold. An electrical equipment area inside a mechanical room buys the least construction of all and shares its ventilation, at the cost of the piping, ductwork and other trades' working space that the mechanical room exists for, every one of which has to be routed around the dedicated electrical space. Which type a project uses follows from the size and heat release of the equipment and from the floor area the building has to give. (5.2)
NOTE Every room type carries the same working space, dedicated electrical space, entrance, illumination and access requirements, and the difference between the three is what else occupies the space and who conditions it. (5.3)
5.4 An electrical room shall not be located directly beneath a space containing plumbing fixtures, floor drains, cooling towers, roof drains or water-filled equipment unless the floor above is waterproofed and the Engineer of Record accepts the location in writing.
5.5 An electrical room containing service equipment, the equipment of an emergency or legally required standby system, or a fire pump controller shall have its finished floor above the design flood elevation indicated on the civil drawings where the site lies in a flood hazard area.
5.6 A room whose floor is below the adjacent exterior grade shall be protected against groundwater and surface water by the waterproofing and subdrainage of the building, and the room shall not be the low point of the drainage system of the floor it stands on.
5.7 A room housing equipment rated over 1000 V shall be enclosed by walls, screens or a fence that make it accessible to qualified persons only, with its door locked or under continuous observation, in accordance with NFPA 70 110.31.
5.8 A room that houses an open generator set, a control-power battery or an energy storage system shall provide the fire separation, the ventilation openings, the floor containment and the ignition source control that GeneratorsEngine GeneratorsResolves to the current adopted revision.sync/generators, DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems and Battery Energy Storage SystemsBattery Energy Storage SystemsResolves to the current adopted revision.sync/battery-energy-storage-systems require of it, and nothing in this standard reduces what those standards demand of the room.

6 Working Space

6.1 Working Space Depth

6.1.1 The basis for the depth of the working space in front of each lineup shall be as indicated in the datasheet.
Working Space Depth Basisradio
● The depth NFPA 70 Table 110.26(A)(1) requires for the voltage to ground and the condition at each lineup
○ The Condition 3 depth of NFPA 70 Table 110.26(A)(1) at every lineup
○ Twice the depth NFPA 70 Table 110.26(A)(1) requires at every lineup
NOTE The table sets the depth by the voltage to ground and by what faces the worker across the space: Condition 1 has exposed live parts on one side and nothing live or grounded on the other, Condition 2 has a grounded surface opposite, which a concrete, masonry or tile wall is taken to be, and Condition 3 has exposed live parts on both sides. At the 277 V to ground of a 480Y/277 V system the three conditions call for 3 ft, 3 ft 6 in. and 4 ft. The table depth is the floor on which most rooms are laid out and costs the least floor area. The Condition 3 depth at every lineup removes the argument about what faces the equipment and keeps a later lineup on the facing wall from shrinking the space, at the cost of floor area in every room. Twice the table depth is the provision under which NFPA 70 110.26(C)(2) permits a single entrance to a room that would otherwise need one at each end, and it is chosen where a second door cannot be had or where drawout breakers and lift trucks need the room to maneuver. (6.1.2)
6.1.3 The depth of the working space shall be measured from the exposed live parts where they are exposed, or from the front of the enclosure or its opening where the parts are enclosed, and shall be clear over the full width and height of the working space.
6.1.4 Where two lineups face each other across one space, the space between them shall satisfy the Condition 3 depth at the higher voltage to ground present, measured between the enclosure faces.
6.1.5 The working space in front of a lineup shall not overlap the working space of equipment on a perpendicular wall unless both spaces remain clear over their full depth, width and height.
6.1.6 Where equipment rated over 1000 V is installed, the working space depth shall be the depth NFPA 70 Table 110.34(A) requires for its voltage and condition, and the datasheet basis above shall apply to that table in place of Table 110.26(A)(1).

6.2 Working Space Width and Height

6.2.1 The width of the working space in front of each lineup shall be the width of the equipment or 30 in., whichever is greater, and shall permit every door and hinged cover of the equipment to open at least 90 degrees, in accordance with NFPA 70 110.26(A)(2).
6.2.2 The height of the working space shall be 6 ft 6 in. or the height of the equipment, whichever is greater, measured from the floor or from the platform the worker stands on, in accordance with NFPA 70 110.26(A)(3).
6.2.3 No luminaire, raceway, pipe, duct, structural member or other equipment shall intrude into the working space over its full depth, width and height, except the equipment's own enclosure extensions that NFPA 70 110.26(A)(3) permits to extend not more than 6 in. beyond the front of the equipment.
NOTE Switchgear, switchboards and motor control centers are commonly 90 in. to 96 in. tall, so in a room that holds them the working space height is set by the equipment and not by the 6 ft 6 in. floor, and a lift truck with its mast raised to the top compartment needs more than either. (6.2.4)
6.2.5 Where a lineup is served by a breaker lift truck or a drawout ramp, the working space shall admit the truck in front of every compartment with its mast raised to the highest compartment, on a level surface, as the standard for that lineup requires.

6.3 Working Space Preservation

6.3.1 The working space shall be kept clear for the life of the building and shall not be used for storage, for the working space of mechanical or plumbing equipment, or for any purpose other than access to the electrical equipment.
6.3.2 Whether the working space is marked on the floor shall be as indicated in the datasheet.
Working Space Floor Markingradio
○ Painted or taped outline of the working space on the floor in front of every lineup
○ None
NOTE A painted outline costs a few hours of layout and paint and gives a facility a line that a stored pallet or a later piece of equipment visibly crosses, which is how the working space survives the first decade of occupancy; no outline leaves the clearance to the memory of whoever reads the record drawings. Where the floor is a resinous finish, the outline is applied under that finish's standard so the two coatings are compatible. (6.3.3)
6.3.4 Where the floor marking is selected, the outline shall be laid out from the as-built enclosure faces at the depth and width the datasheet basis requires, and shall be shown on the record coordination drawing.

7 Dedicated Electrical Space

7.1 Space Above and Below the Equipment

7.1.1 The space equal to the width and depth of each lineup, from the floor to 6 ft above the equipment or to the structural ceiling where that is lower, shall be dedicated to the electrical installation, in accordance with NFPA 70 110.26(E)(1)(a).
7.1.2 No piping, duct, leak protection apparatus or other equipment foreign to the electrical installation shall be installed in or pass through the dedicated electrical space.
7.1.3 A suspended, dropped or similar ceiling that does not add strength to the building structure shall not be treated as the structural ceiling for the purpose of the dedicated electrical space, in accordance with NFPA 70 110.26(E)(1)(d).
NOTE The dedicated space is the volume the electrical trade needs for the raceways, the busway and the cable entries that rise out of or drop into the equipment, and it is the volume every other trade finds convenient for a main, because it runs along the wall above a row of enclosures no one else occupies. The 6 ft above the equipment is not free ceiling plenum, and a ceiling hung below structure does not shorten it. (7.1.4)
7.1.5 The clear height of each room from the finished floor to the underside of the structure shall be not less than the height of the tallest lineup plus 6 ft, and not less than the height the lift truck, the arc-resistant exhaust plenum or the top conduit entries of any lineup require, and shall be as indicated on the electrical room coordination drawing.

7.2 Foreign Systems Above the Dedicated Space

7.2.1 Where the structural ceiling is more than 6 ft above the equipment, a system foreign to the electrical installation shall be permitted above the dedicated electrical space only where protection is installed below it that prevents a leak, condensation or a break in that system from reaching the equipment, in accordance with NFPA 70 110.26(E)(1)(b).
7.2.2 The protection below a foreign system shall be a drip shield or pan of sheet metal or rigid plastic, sloped and drained to a point outside the dedicated electrical space and the working space, and shall extend not less than 6 in. beyond the system it protects on every side.

7.3 Arc Exhaust Discharge

7.3.1 Where the room houses arc-resistant switchgear, the room shall provide the exhaust plenum path and the discharge location shown on the reviewed shop drawings of that switchgear, discharging to the outdoors or to a space in which no person stands, and the plenum shall not reduce the dedicated electrical space of any other lineup.
7.3.2 Where the plenum discharges through a rated wall or into a duct, the penetration shall be firestopped under FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping and the duct shall be of the construction and the pressure rating the switchgear manufacturer requires for the arc exhaust.
NOTE An arc-resistant lineup directs the products of an internal fault through a plenum to a point where no worker stands, and the rating applies only when that path exists and is clear. The switchgear standard tests and rates the plenum; the room has to give it somewhere to go. (7.3.3)

8 Entrances and Egress

8.1 Number of Entrances

8.1.1 The number of entrances to the working space of each room shall be as indicated in the datasheet.
Number of Entrances to the Working Spaceradio
○ One entrance
○ Two entrances, one at each end of the working space
Derived — the ampere rating and the width of the equipment in the room and the exceptions of NFPA 70 110.26(C)(2) and 110.33(A) (by default)
8.1.2 Where the room contains equipment rated 800 A or more and over 6 ft wide that holds overcurrent, switching or control devices, there shall be an entrance not less than 24 in. wide and 6 ft 6 in. high at each end of the working space, in accordance with NFPA 70 110.26(C)(2), unless the room satisfies one of the exceptions that section permits.
8.1.3 A single entrance shall be permitted to such a room only where the location permits a continuous and unobstructed way of egress from the working space, or where the working space depth is twice that NFPA 70 Table 110.26(A)(1) requires and the entrance is at least that doubled depth from the equipment, so that a worker can move away from the equipment in either direction.
8.1.4 Where the room contains equipment rated over 1000 V, the entrances shall satisfy NFPA 70 110.33(A), with an entrance at each end of any switchgear or control assembly over 6 ft wide unless an exception that section permits applies.
NOTE The one-entrance rule and the two-entrance rule both exist so that a worker who has an arcing fault in front of them has a way out that does not pass the fault. The second door costs a door, a frame, hardware and a wall opening; the doubled depth costs floor area along the whole lineup; the unobstructed egress exception costs nothing but is available only where the room's shape gives it. (8.1.5)
8.1.6 The door clear opening width of each entrance shall be as indicated in the datasheet.
Door Clear Opening Widthrange
Not less than
in
3236424860728496
Per drawings — the electrical room coordination drawing (deferred by default)
8.1.7 Every entrance shall pass the largest shipping section of the equipment in the room with its packaging removed, and the Contractor shall verify the clear opening of every door against the reviewed shipping dimensions before the frame is ordered.
8.1.8 Where a section of the largest equipment in the room cannot pass through the smallest door of the room, the Contractor shall report the conflict to the Engineer of Record before the frame is ordered, and shall not resolve it by removing a wall after the equipment is set.
NOTE The door that lets the equipment in is the door that lets its replacement out, and a room built around a switchgear section that entered through a wall opening before the wall was closed has committed the Owner to opening that wall again. A pair of doors with a removable mullion is the common answer where a single leaf cannot pass the section. (8.1.9)

8.2 Door Swing and Hardware

8.2.1 Where the room contains equipment rated 800 A or more, every personnel door within 25 ft of the nearest edge of the working space shall open in the direction of egress and shall be equipped with listed panic hardware or listed fire exit hardware, in accordance with NFPA 70 110.26(C)(3).
8.2.2 Where the room contains equipment rated over 1000 V, every personnel door shall open in the direction of egress and shall be equipped with listed panic hardware or listed fire exit hardware, in accordance with NFPA 70 110.33(A)(3).
8.2.3 The panic hardware policy for electrical room doors not covered by the two preceding clauses shall be as indicated in the datasheet.
Panic Hardware Policyradio
○ Listed panic hardware or fire exit hardware on every electrical room door
○ Panic hardware only where NFPA 70 110.26(C)(3) or 110.33(A)(3) requires it
NOTE Panic hardware on every electrical room door gives every room the same exit, costs a panic device and an outswinging leaf per door, and removes the question of which rooms crossed the 800 A threshold when a lineup was enlarged; hardware only where the code requires it costs less on a building with many small closets and leaves a closet door that swings into the corridor to the Owner's keying and the lever on the inside. Both are code-compliant; the difference is what a facility wants every one of its electrical doors to do. (8.2.4)
8.2.5 Every electrical room door shall be openable from inside the room without a key, a tool or special knowledge, and no locking device shall prevent egress from the room.
8.2.6 A door in a rated wall shall be a listed fire door assembly of the rating Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies requires for the opening, installed under NFPA 80, and its panic hardware shall be fire exit hardware listed for that assembly.
8.2.7 The locking provision of each electrical room door shall be as indicated in the datasheet.
Door Lockingradio
● Keyed lockset on the Owner's keying system
○ Electronic access control
NOTE A keyed lockset costs a cylinder and a key record and is what most buildings fit on a room that qualified persons enter a few times a year; electronic access control costs a reader, a controller, a strike or electrified device and cabling, and buys a record of who entered and when, the ability to revoke a credential without rekeying, and a door position signal the facility can alarm on. The electronic provision earns its cost where the Owner's security program already covers the building or where the room holds the service, the emergency system or equipment over 1000 V. (8.2.8)
8.2.9 Where electronic access control is selected, the door shall be placed on the building's access control system under Access Control SystemsAccess Control SystemsResolves to the current adopted revision.sync/access-control-systems, the locking device shall fail to a state that permits free egress, and a mechanical key override shall be provided for entry on loss of the system.
8.2.10 The doors, frames, panic hardware, closers and locksets shall be furnished and installed under Doors Frames And HardwareDoors, Frames, and HardwareResolves to the current adopted revision.sync/doors-frames-and-hardware or Door HardwareDoor HardwareResolves to the current adopted revision.sync/door-hardware as the project's door package is organized, to the swing, clear opening, rating and hardware this standard requires.
8.2.11 A mantrap, a turnstile or a delayed-egress device shall not be installed on an electrical room door unless the Owner requires it in writing and the Authority Having Jurisdiction accepts it.

8.3 Egress Path

8.3.1 A continuous and unobstructed path not less than the width of the working space shall be maintained from every point of the working space to each entrance, and no equipment, pad, pipe or stored item shall narrow it.
8.3.2 The egress path from the working space shall be shown on the coordination drawing and shall not pass through the working space of another lineup where a second entrance or the doubled working space depth is relied on to satisfy NFPA 70 110.26(C)(2).

9 Enclosing Construction

9.1 Fire-Resistance Rating

9.1.1 The fire-resistance rating of the walls, floor and ceiling enclosing each electrical room shall be as indicated in the datasheet.
Enclosing Construction Fire-Resistance Ratingrange
Not less than
hours
123
Per drawings — the code analysis drawing (deferred by default)
NOTE No code rates an electrical room as such; the rating is set by what the room holds. NFPA 70 450.21(B) puts a dry-type transformer rated above 112.5 kVA in a room of fire-resistant construction unless its insulation system and enclosure meet the exception that section provides, and fire-resistant construction is one hour as Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code defines it. NFPA 110 Chapter 7 puts a Level 1 generator set installed indoors in a room separated by two-hour construction. Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code separates a stationary battery room and a fire pump room as incidental uses, and separates the room from an adjacent occupancy of a different group. An Owner's insurer sometimes asks for more than any of them, and a room that holds nothing on those lists carries no rating at all. The code analysis is where those drivers are reconciled room by room, which is why the value is read from it. (9.1.2)
9.1.3 The rated assemblies enclosing the room shall be built to the design numbers Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies documents for them, under Gypsum Board AssembliesGypsum Board AssembliesResolves to the current adopted revision.sync/gypsum-board-assemblies or Unit MasonryUnit MasonryResolves to the current adopted revision.sync/unit-masonry as the assembly is constructed, and shall extend from the floor to the underside of the floor or roof above.
9.1.4 Every raceway, busway, cable tray, pipe, duct and louver that penetrates a rated wall, floor or ceiling of the room shall be firestopped under FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping, and every duct or louver opening in a rated wall shall carry the fire damper or combination fire and smoke damper Louvers And DampersLouvers and DampersResolves to the current adopted revision.sync/louvers-and-dampers requires for that assembly.
9.1.5 The extent of the rated enclosure of each room and the rating of each assembly shall be as indicated on the code analysis drawing.

9.2 Walls, Ceiling and Finishes

9.2.1 The walls and the ceiling of the room shall have a hard, sealed surface that does not shed dust or fibers, and where the parties disagree whether a surface sheds, the Engineer of Record shall make the determination.
NOTE Exposed insulation, unsealed concrete masonry and unpainted gypsum board are each a surface that sheds into the ventilation openings of the equipment below them, and a room whose walls are painted and whose ceiling is sealed is one in which the equipment interior stays clean between maintenance cycles. (9.2.2)
9.2.3 A suspended acoustical ceiling shall not be installed over the dedicated electrical space of any lineup, and where one is installed elsewhere in the room it shall not reduce the clear height this standard requires.
9.2.4 Interior wall and ceiling surfaces shall be painted under Interior PaintingInterior PaintingResolves to the current adopted revision.sync/interior-painting before the equipment is set, and no painting shall be performed over installed equipment.

10 Foreign Systems and Water Protection

10.1 Piping and Ductwork Elsewhere in the Room

10.1.1 The provision for piping and ductwork foreign to the electrical installation outside the dedicated electrical space shall be as indicated in the datasheet.
Foreign Piping and Ductwork Outside the Dedicated Electrical Spaceradio
○ Not permitted anywhere in the room
○ Permitted outside the dedicated electrical space and the working space, with protection against leaks and condensation
NOTE The code excludes foreign systems from the dedicated electrical space and permits them elsewhere in the room with protection. A room that admits none of them costs other trades a longer route around the room and buys a room in which no pipe can ever drip on a lineup and no duct can ever be hung in a working space; a room that admits them outside the clearances costs drip shields, leak protection and a coordination drawing that every trade honors, and buys the shorter routing that a crowded floor plate often needs. On a floor where the electrical room sits in the core beside the mechanical shaft, the second provision is frequently the only one the plan allows. (10.1.2)
10.1.3 Where foreign piping is permitted in the room, no pipe carrying water, steam, refrigerant, fuel or drainage shall be routed above any electrical equipment or above its working space, and every such pipe elsewhere in the room shall be provided with the drip shield this standard requires for foreign systems above the dedicated space.
10.1.4 Where foreign ductwork is permitted in the room, it shall be routed outside the dedicated electrical space and the working space, and any duct that serves a space other than the room shall carry no access door, damper or coil that is serviced from inside the room.
10.1.5 Water-based fire suppression piping serving the room shall not pass through the dedicated electrical space of any lineup, and the sprinkler protection of the room shall be arranged under Wet Pipe Fire Sprinkler SystemsWet-Pipe Fire Sprinkler SystemsResolves to the current adopted revision.sync/wet-pipe-fire-sprinkler-systems or Pre Action And Deluge Sprinkler SystemsPre-Action and Deluge Sprinkler SystemsResolves to the current adopted revision.sync/pre-action-and-deluge-sprinkler-systems so that its piping complies with NFPA 70 110.26(E)(1).
NOTE NFPA 13 permits sprinklers to be omitted from an electrical equipment room that is dedicated to dry-type electrical equipment, enclosed in two-hour construction and used for no storage, and the fire protection standards decide for each project whether the room is sprinklered, pre-action protected, clean agent protected or left to that omission. This standard decides only where the piping cannot go. (10.1.6)
10.1.7 A roof drain leader, a domestic water riser, a sanitary stack or a storm drain shall not be routed through an electrical room under either provision of the datasheet.

10.2 Water Entry at the Door

10.2.1 The water barrier at the door of each room shall be as indicated in the datasheet.
Door Threshold Curbradio
● None
○ Raised curb or threshold at every door
NOTE A curb or a raised threshold holds a sprinkler discharge, a cleaning cart spill or a flooded corridor out of the room, at the cost of a step at every door that a lift truck, a breaker cart and a pallet jack have to ramp over. It earns its cost where the room is below grade, where it sits beside a wet room or a loading dock, or where the corridor outside it is washed down; on an upper floor beside dry offices it is a tripping hazard that protects against nothing. (10.2.2)
10.2.3 Where a curb or raised threshold is selected, it shall be not less than 2 in. above the adjacent floor, shall be continuous across the opening, and shall be provided with a ramp or a removable plate on the room side so that equipment can be rolled across it.

10.3 Floor Drainage

10.3.1 The floor drain provision of each room shall be as indicated in the datasheet.
Floor Drainradio
● Not provided
○ Provided at a low point of the floor, clear of the working space and the dedicated electrical space
NOTE A floor drain removes the water that a sprinkler discharge, a leaking pipe or a flooded corridor puts on the floor before it reaches the base of a lineup, and it costs a trap that dries out and vents sewer gas into a room that is rarely entered, a trap primer to keep it wet, and a sloped floor under equipment that wants to be level. A room with no water source in it and nothing wet beside it has nothing for a drain to remove, which is why most electrical rooms have none; a room that is sprinklered, that holds a vented battery or that lies below grade has a reason for one. (10.3.2)
10.3.3 Where a floor drain is selected, it shall be furnished under Sanitary Drainage SpecialtiesSanitary Drainage SpecialtiesResolves to the current adopted revision.sync/sanitary-drainage-specialties with a trap primer, the floor shall slope to it at not less than 1/8 in. per foot from the pad edges, and the drain shall be located outside the working space and the dedicated electrical space of every lineup.
10.3.4 Where a floor drain is selected in a room that holds a vented battery, the drain shall discharge through the neutralization provision DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems requires and not directly to the sanitary system.

11 Room Environment

11.1 Heat-Release Basis

11.1.1 The basis on which the heat released into each room is computed shall be as indicated in the datasheet.
Heat-Release Basisradio
● Full-load losses of every item of equipment in the room
○ Losses at the calculated design load of each item of equipment
NOTE Full-load losses are the values the equipment standards require each manufacturer to state, so they are available from the reviewed shop drawings without a load study, and they give a room that holds its limit on the day every feeder is loaded to its rating; the sum overstates the room's heat on every other day, which oversizes the ventilation or cooling by the ratio of design load to rating. Design-load losses give a smaller fan or cooling unit, at the cost of a load calculation that has to be redone when the building's load grows, and of a room that runs hot the year that growth arrives. (11.1.2)
11.1.3 The Contractor shall compile the room heat-release schedule from the reviewed shop drawings of every item of equipment in the room, at the basis selected in the datasheet, and shall issue it to the trade responsible for the room's ventilation or cooling before that design is fixed.
11.1.4 The heat-release schedule shall include the losses of every transformer, drive, UPS module, battery charger, switchgear and switchboard section, motor control center section, panelboard, busway run and generator set in the room, and the heat released by any open generator set shall be the value the generator standard states for the set with its radiator discharge ducted out of the room.

11.2 Heat Rejection Method

11.2.1 The method by which each room rejects the heat released into it shall be as indicated in the datasheet.
Heat Rejection Methodradio
○ Ventilation with outdoor air or building air
○ Mechanical cooling
○ Ventilation with mechanical cooling for the hours ventilation cannot hold the limit
NOTE Ventilation moves the room's heat out on a stream of outdoor or building air and costs a fan, a louver or a transfer opening and a damper at the rated wall; it holds the room to the outdoor temperature plus the rise the airflow allows, so it holds a 40°C limit where Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum leaves margin below it and cannot hold a lower limit on a hot day at all, and it brings in whatever the outdoor air carries. Mechanical cooling costs a cooling unit, a refrigerant or chilled-water connection and a condensate drain, and holds any limit in any weather with filtered, dehumidified air, which is what electronics, drives and batteries ask for; it also makes the room's temperature depend on a machine that can fail. Ventilation backed by cooling costs both and runs the fan for most of the year with the cooling unit for the hottest hours, which is the lowest energy of the three where the limit is low and the climate is mild. The method follows from the limit the equipment imposes, from the site climate and from the hours the room's load runs, so none of the three is the norm. (11.2.2)
11.2.3 The ventilation or cooling of the room shall hold the room air temperature within the limits of the datasheet with every item of equipment releasing heat at the heat-release basis and with the outdoor air at Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum.
11.2.4 The fans, louvers, dampers, ductwork and cooling units that condition the room shall be furnished and installed under HVAC FansHVAC FansResolves to the current adopted revision.sync/hvac-fans, Louvers And DampersLouvers and DampersResolves to the current adopted revision.sync/louvers-and-dampers, HVAC DuctworkHVAC DuctworkResolves to the current adopted revision.sync/hvac-ductwork, Split System Air ConditionersSplit-System Air Conditioners and Heat PumpsResolves to the current adopted revision.sync/split-system-air-conditioners, Fan Coil UnitsFan-Coil UnitsResolves to the current adopted revision.sync/fan-coil-units or Computer Room Air ConditioningComputer Room Air Conditioning UnitsResolves to the current adopted revision.sync/computer-room-air-conditioning as the mechanical design selects them, and this standard governs only the conditions the room has to hold.
11.2.5 Where ventilation is selected, the intake and the discharge shall be placed so that the air path crosses the equipment that releases the heat, so that the discharge is not drawn back into the intake, and so that the intake does not draw from a loading dock, a parking structure, a kitchen exhaust, a generator exhaust or a cooling tower plume.
11.2.6 Where ventilation is selected and the intake is exposed to dust, salt, corrosive vapor or vehicle exhaust, the intake air shall be filtered, and where the parties disagree whether the exposure exists, the Engineer of Record shall make the determination.
11.2.7 Where mechanical cooling is selected, the cooling unit shall be located outside the dedicated electrical space and the working space, its condensate shall be drained to a point outside the room or to the floor drain where one is selected, and no refrigerant or chilled-water piping shall pass above any electrical equipment.
NOTE A cooling unit hung above a switchboard is a water source above live parts, and a condensate line routed to the nearest drain through the dedicated space is a pipe where the code forbids one. The unit belongs on a wall or a floor stand outside both clearances, with its piping routed the long way. (11.2.8)
11.2.9 Where the room holds the equipment of an emergency or legally required standby system, the cooling or ventilation of the room shall be supplied from the same system so that the room holds its limits while the normal source is lost.

11.3 Temperature Limits

11.3.1 The upper limit of the room air temperature shall be as indicated in the datasheet.
Room Air Temperature Upper Limitrange
Not more than
°C
253035404550
Derived — the lowest rated ambient temperature among the equipment in the room, taken from the reviewed shop drawings (by default)
NOTE Switchgear, switchboards, panelboards, motor control centers and dry-type transformers carry their nameplate ratings at a 40°C ambient, so a room of such equipment holds 40°C with no derating; a drive, a UPS module, a battery charger and most electronic protective relays are rated at 40°C as well but age faster above 25°C to 30°C, and a lead-acid battery loses half its service life for every 8°C to 10°C above 25°C, which is why a room that holds those is held lower. The limit is the lowest rated ambient in the room, and the engineer overrides it downward where the service life of the electronics or the battery is worth the cooling. (11.3.2)
11.3.3 The lower limit of the room air temperature shall be as indicated in the datasheet.
Room Air Temperature Lower Limitrange
Not less than
°C
-10-55101520
NOTE Switchgear and switchboards are rated for a minimum ambient of -5°C to -30°C depending on the standard they are built to, a drive and a UPS module for 0°C, and a lead-acid battery loses capacity below 20°C and is sized for the lowest temperature it sees, so the lower limit follows from the most cold-sensitive item in the room. An interior room on an occupied floor never approaches any of these limits and needs no heat; a room on an exterior wall of an unheated structure, a room beside a loading dock door or a room that ventilates with outdoor air through the winter needs a heater to hold the limit at Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum, and the limit then decides how large that heater is. (11.3.4)
11.3.5 Where the losses of the equipment and the heat of the surrounding building cannot hold the lower limit with the outdoor air at Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum, the room shall be heated by a unit heater furnished under Unit HeatersUnit HeatersResolves to the current adopted revision.sync/unit-heaters, located outside the dedicated electrical space and the working space, and where ventilation is selected the ventilation shall be dampered or staged so that it does not drive the room below the limit.
11.3.6 Where the room holds a control-power battery or an energy storage system, the room shall hold the temperature range DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems or Battery Energy Storage SystemsBattery Energy Storage SystemsResolves to the current adopted revision.sync/battery-energy-storage-systems requires for the battery, which shall govern over the limits of the datasheet where it is narrower.

11.4 Humidity

11.4.1 The room shall be held non-condensing, and the surface temperature of every enclosure in the room shall remain above the dew point of the room air at every operating condition.
11.4.2 The upper limit of the room relative humidity shall be as indicated in the datasheet.
Room Relative Humidity Upper Limitrange
Not more than
% RH
506070809095
NOTE A ventilated room follows the outdoor humidity and the only limit it can hold is the non-condensing condition, so a ventilated room's limit is written at the high end to record what the equipment tolerates rather than what the room controls; a mechanically cooled room dehumidifies as it cools and holds a limit of 50 to 60 percent without a separate provision, which is where electronics, drives and the insulation of medium-voltage equipment are kept dry. A cold-weather room with an outdoor-air intake can reach saturation on a mild wet day after a cold night, which is the condition under which an enclosure sweats and a bus flashes over, and it is the reason a ventilated room in a humid climate is given space heaters in the equipment under the equipment standards rather than a humidity limit here. (11.4.3)
11.4.4 Where the datasheet selects mechanical cooling, the cooling unit shall hold the relative humidity limit of the datasheet at the room's design heat release.

11.5 Battery Rooms

11.5.1 A room that houses a vented battery shall provide the ventilation openings, the exhaust path, the hydrogen detector location, the eyewash and safety shower and the floor containment that DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems or Battery Energy Storage SystemsBattery Energy Storage SystemsResolves to the current adopted revision.sync/battery-energy-storage-systems requires for the battery, and those requirements shall be shown on the coordination drawing.
11.5.2 The ventilation of a battery room shall exhaust from the highest point of the room, shall not recirculate to another electrical room, and shall not pass through the ventilation or cooling of a room that holds other electrical equipment.
11.5.3 Where a battery is installed in a cabinet inside an electrical room rather than in its own room, the room ventilation or cooling shall account for the cabinet's hydrogen venting and heat release as the battery standard states them.

11.6 Room Condition Monitoring

11.6.1 The room conditions reported to the building automation system shall be as indicated in the datasheet.
Room Conditions Reported to the Building Automation Systemcheckbox
☐ High room air temperature
☐ Loss of ventilation or cooling
☐ Water on the floor
☐ Door open
11.6.2 Each selected condition shall be reported to the building automation system under Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system as an alarm, with the high temperature alarm set 5°C below the upper limit of the datasheet, the water alarm from a leak detection cable or spot sensor on the floor at the low point of the room, and the door alarm from the door position switch of the access control system where electronic access control is selected.
11.6.3 Where the room holds a UPS, the points the UPS reports to the building automation system under Uninterruptible Power Supply SystemsUninterruptible Power Supply SystemsResolves to the current adopted revision.sync/uninterruptible-power-supply-systems shall be carried on the same network as the room's own alarms, and the room's high temperature alarm shall be set below the UPS's own ambient alarm so that the room alarms first.
NOTE An electrical room is entered a few times a year, so the cooling unit that fails in June is found when the switchgear trips on an overtemperature in August unless the room reports the condition the day it occurs. The four points cost a sensor, a cable and a point on a controller each, and a room that holds the service, the emergency system, a UPS or a battery is one in which that cost is small against the day they buy. A closet of panelboards on an occupied floor rarely needs any of them. (11.6.4)

12 Illumination and Convenience Power

12.1 Working Space Illumination

12.1.1 Illumination shall be provided for the working space about every lineup in the room, in accordance with NFPA 70 110.26(D) for equipment rated 1000 V and below and NFPA 70 110.34(D) for equipment rated over 1000 V.
12.1.2 The maintained illuminance at the working plane of each working space shall be as indicated in the datasheet.
Working Space Illuminancerange
Not less than
fc
1020305075100
NOTE The code requires illumination and sets no level. Thirty footcandles, measured vertically at the equipment face at the height of the device handles, is the level most illumination references recommend for an electrical equipment room and is enough to read a nameplate, identify a breaker and see a connection; 50 fc and above are chosen where infrared inspection windows are read, where a lineup is densely labeled or where relay settings are entered from a front panel; 10 to 20 fc is a closet of panelboards whose directories are read at arm's length. The level is measured in the working space and not at the center of the room, because the luminaires sit outside the dedicated space and the vertical face of the equipment is what the worker reads. (12.1.3)
12.1.4 Every luminaire in the room shall be located outside the dedicated electrical space of every lineup, and shall be located so that a person relamping or servicing it is not exposed to live parts and does not stand in front of an open compartment to reach it.
12.1.5 The luminaires shall be furnished under Lighting FixturesInterior Lighting Fixtures (Luminaires)Resolves to the current adopted revision.sync/lighting-fixtures and the lighting power of the room shall comply with Adopted Energy CodeAdopted Energy CodeParameterEach project supplies its own value.adopted-energy-code.
12.1.6 The control of the working space illumination shall be as indicated in the datasheet.
Working Space Lighting Controlradio
○ Manual switches at each entrance, with no automatic control
○ Manual switches at each entrance, with an occupancy sensor that turns the lighting off
○ Manual switches at each entrance, with an occupancy sensor that turns the lighting on and off
NOTE NFPA 70 110.26(D) forbids control of the working space illumination by automatic means alone, so every provision begins with a manual switch at each entrance. Manual switches alone cost the least and leave the lights on until the last person out turns them off, which the energy code accepts in some editions for an electrical room and not in others. A sensor that only turns the lighting off satisfies an automatic shutoff requirement and leaves the worker in control of turning it on; it turns the lights off on a worker who stands still in front of a lineup long enough for the sensor to time out, which a sensor that also turns them on recovers from on the first movement, at the cost of a sensor that switches the lights on for every door opening. The sensor's coverage and time delay are set under Lighting ControlsLighting ControlsResolves to the current adopted revision.sync/lighting-controls so that a worker in the working space is within its view. (12.1.7)
12.1.8 Where an occupancy sensor is selected, the sensor shall cover the full working space of every lineup in the room with no part of the space outside its view, and its time delay shall be not less than 30 minutes.
12.1.9 The automatic shutoff of the room lighting shall comply with Adopted Energy CodeAdopted Energy CodeParameterEach project supplies its own value.adopted-energy-code where that code requires it for an electrical equipment room.

12.2 Emergency Illumination

12.2.1 Emergency illumination shall be provided in the working space of the service disconnecting means where it is installed indoors, and in the working space of the equipment of an emergency system, in accordance with NFPA 70 700.16, and shall not depend on the equipment whose working space it illuminates.
12.2.2 The source of the emergency illumination in each room shall be as indicated in the datasheet.
Emergency Illumination Sourceradio
○ A luminaire with an integral battery in the room
○ A luminaire supplied from the emergency or legally required standby system
NOTE A battery luminaire costs a unit and a battery that is replaced every few years, is independent of every circuit in the room and lights the room during the maintenance outage of the very equipment that supplies the emergency system; a luminaire on the emergency branch costs a circuit from the emergency panel, lasts as long as the building and is dark during a maintenance outage of the transfer switch or the emergency panel unless that panel is elsewhere. The battery unit is the choice in the room that holds the emergency system itself; the emergency branch is the choice in a room supplied from an emergency panel in another room. (12.2.3)
12.2.4 The emergency luminaires shall be furnished under Emergency And Egress LightingEmergency and Egress LightingResolves to the current adopted revision.sync/emergency-and-egress-lighting and shall illuminate the working space of every lineup in the room and the path from it to each entrance.

12.3 Convenience Receptacle

12.3.1 The convenience receptacle provision of each room shall be as indicated in the datasheet.
Convenience Receptacle Provisionradio
○ One receptacle within 25 ft of the service equipment
○ One receptacle within 25 ft of every lineup in the room
○ One receptacle at each entrance to the working space
NOTE NFPA 70 210.63 requires a 125 V, single-phase, 15 A or 20 A receptacle within 25 ft of indoor service equipment, which is what the first provision records and what a room that holds only the service needs. A receptacle within 25 ft of every lineup puts a test instrument, a work light and a vacuum within a cord's reach of every compartment in a long room, at the cost of a receptacle per lineup; a receptacle at each entrance puts the cord where the worker enters and where the lift truck is charged, at the cost of a receptacle per door, and in a two-door room covers most lineups by default. (12.3.2)
12.3.3 The receptacle shall not be supplied from the load side of the equipment whose working space it serves, so that the receptacle remains energized while that equipment is de-energized for maintenance.
12.3.4 The receptacle shall be ground-fault circuit-interrupter protected where NFPA 70 210.8 requires it for the location, and shall be furnished under Wiring DevicesWiring DevicesResolves to the current adopted revision.sync/wiring-devices.
12.3.5 The receptacle shall be located outside the dedicated electrical space of every lineup, and shall not be mounted on the equipment enclosure.

12.4 Lighting and Receptacle Circuit Source

12.4.1 The lighting and the receptacle circuits of the room shall be supplied from a panelboard outside the room or from a panelboard in the room that is not the equipment whose working space they serve, and shall not be supplied from the load side of the service disconnecting means or the main device of the lineup they illuminate.
NOTE A room whose lights and receptacles are fed from the main panelboard in the room goes dark the moment that panelboard is de-energized for maintenance, which is the moment the worker needs the lights most. The error is common because the main panelboard is the nearest source, and it is caught on the coordination drawing, where the circuit source is written beside each luminaire. (12.4.2)

13 Housekeeping Pads and Floor

13.1 Housekeeping Pad Provision

13.1.1 The housekeeping pad provision for the floor-standing equipment in each room shall be as indicated in the datasheet.
Housekeeping Pad Provisionradio
● A housekeeping pad under every floor-standing lineup
○ A housekeeping pad only where the equipment standard requires one
○ No housekeeping pads
NOTE A pad under every lineup lifts every enclosure base above the water a sprinkler, a leak or a washdown puts on the floor, gives the conduits entering from below their bending radius, and gives the anchors a thickness of concrete the floor slab alone does not always have; it costs a pad per lineup and a step up to every enclosure. A pad only where the equipment standard requires one leaves a wall-hung panelboard and a transformer on a floor stand without one and puts the switchgear on one, which is what most of the equipment standards already ask. Setting equipment on the finished floor costs nothing and is chosen where the slab is thick enough to anchor into, where no water can reach the floor and where a lift truck has to roll up to every compartment without a ramp. (13.1.2)
13.1.3 Every housekeeping pad shall be constructed under Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads, at the height, projection and thickness that standard sets, and its plan dimensions shall be as indicated on the electrical room coordination drawing.
13.1.4 Where a pad is provided under a lineup served by a lift truck, the surface in front of the lineup shall be at the pad surface or shall be ramped to it, as the standard for that lineup requires.
13.1.5 The floor of the room shall be designed for the weight of the equipment and of the lift truck as indicated on the structural drawings, and the Contractor shall report any equipment whose reviewed shipping weight exceeds the weight the structural drawings state before the equipment is delivered.
13.1.6 Every item of equipment in the room shall be anchored to the pad or the floor as its own standard requires, with the anchorage designed under Vibration Isolation And Seismic RestraintVibration Isolation and Seismic RestraintResolves to the current adopted revision.sync/vibration-isolation-and-seismic-restraint where Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category requires nonstructural components to be restrained.

13.2 Floor Finish

13.2.1 The floor finish of each room shall be as indicated in the datasheet.
Floor Finishselect
Sealed concrete
Resinous floor coating
Static-dissipative resinous floor
NOTE Sealed concrete costs a sealer rolled on the slab, does not dust, and is what most electrical rooms are given; a resinous floor coating costs a prepared slab and a fluid-applied system and buys a floor that cleans, that shows a leak and that resists the electrolyte of a vented battery; a static-dissipative resinous floor adds a ground connection and a controlled surface resistance and is chosen in a room of electronic relays, a control room or a battery room where the Owner's electrostatic discharge program asks for it. The resinous systems are furnished under Resinous FlooringResinous FlooringResolves to the current adopted revision.sync/resinous-flooring, and the ground connection of a static-dissipative floor is made under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding. (13.2.2)
13.2.3 The floor finish shall be complete and cured before the equipment is set, and the floor under every lineup shall be level to the tolerance the equipment standard requires.
13.2.4 Carpet, resilient tile and any finish that sheds fibers or holds moisture shall not be installed in an electrical room.

14 Grounding Provisions in the Room

14.1 The room ground bar provision shall be as indicated in the datasheet.
Room Ground Barradio
○ A ground bar in every electrical room
○ A ground bar only in a room that houses a separately derived system or more than one lineup
○ Not provided
NOTE A ground bar in every room gives the room one visible point where the equipment grounds, the grounding electrode taps of the derived systems and the bonding conductors of the doors, racks and trays are brought together and can be tested, at the cost of a bar, a bonding conductor sized to the largest system landed on it and a wall space; a bar only where a derived system or a second lineup exists spends that cost where there is more than one thing to tie together; no bar leaves each lineup's ground bus to do the work, which the code permits and which a closet with one panelboard rarely needs more than. (14.2)
14.3 Where a ground bar is selected, it shall be a copper bar mounted on insulated standoffs at a height of 18 in. to 24 in. above the floor on a wall outside the working space, and shall be bonded to the grounding electrode system under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding by a conductor sized as that standard requires for the systems landed on it.
14.4 The metal doors, frames, ladders, racks and cable trays of the room shall be bonded to the ground bar or to the nearest equipment ground bus where Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding selects that bonding, and the grounding electrode system serving the room shall be installed under that standard.
14.5 Where the room also houses telecommunications equipment, the telecommunications ground bar shall be installed and bonded under Telecommunications BondingTelecommunications Bonding and GroundingResolves to the current adopted revision.sync/telecommunications-bonding and shall not be used as the room ground bar of this standard.

15 Room Signage

15.1 The signs installed on the entry door of each room shall be as indicated in the datasheet.
Room Door Signscheckbox
☑ Room identification sign
☑ Sign restricting entry to authorized persons
☐ Sign prohibiting storage in the room
☐ Arc-flash and shock hazard warning sign
NOTE The signs on the door are what a building's staff, its cleaners and its tenants read; the labels on the equipment inside are what the qualified person reads, and Equipment LabelingElectrical Equipment LabelsResolves to the current adopted revision.sync/equipment-labeling governs those. A room identification sign lets the responder and the facility staff find the room; a sign restricting entry keeps the unqualified out, which the code requires for a room over 1000 V and the Owner's safety program asks for on the rest; a storage sign is the cheapest defense of the working space; an arc-flash warning on the door tells the entering worker that the equipment inside carries incident energy labels before the door is opened, and it is chosen where the facility's electrical safety program under Electrical Safety ProgramElectrical Safety ProgramResolves to the current adopted revision.sync/electrical-safety-program uses it. (15.2)
15.3 Every entrance to a room that houses equipment rated over 1000 V shall carry a warning sign reading DANGER, HIGH VOLTAGE, KEEP OUT, in accordance with NFPA 70 110.34(C), whatever the datasheet selects.
15.4 A sign that restricts entry, prohibits storage or warns of a hazard shall be a rigid plastic or aluminum sign in the signal word, color and layout of ANSI Z535.4, with characters not less than 1 in. high, fastened to the door or the wall beside it with its center 60 in. above the floor.
15.5 The room identification sign shall be fabricated and installed under SignageSignageResolves to the current adopted revision.sync/signage where the project has a sign schedule, and shall carry the room name and number shown on the electrical plans.
15.6 No sign required by this standard or by Equipment LabelingElectrical Equipment LabelsResolves to the current adopted revision.sync/equipment-labeling shall be obstructed by a door in its open position, by equipment or by a finish.

16 Coordination Drawing

16.1 The electrical Contractor shall prepare a coordination drawing of each electrical room at a scale not smaller than 1/4 in. to 1 ft in plan and in elevation, from the reviewed shop drawings of every item of equipment in the room.
16.2 The coordination drawing shall show every lineup at its reviewed dimensions, the working space in front of, beside and behind each as the datasheet basis requires, the dedicated electrical space above and below each, the clear height of the room, every entrance with its swing and clear opening, the egress path, every housekeeping pad, every raceway, busway, cable tray, pipe, duct, louver and damper that enters or crosses the room, the arc exhaust plenum and its discharge where one exists, every luminaire with its circuit source, every receptacle with its circuit source, the ground bar, the cooling unit or ventilation openings, the floor drain and the curb where selected, and every sign on the door.
16.3 The coordination drawing shall identify every foreign system in the room against the provision selected in the datasheet, and shall show the drip shield or protection below each one that is permitted.
16.4 The coordination drawing shall be issued to every trade that attends the coordination meeting, and no trade shall install work in the room that departs from it without a revision reviewed by the Engineer of Record.
16.5 Where the reviewed shop drawings of an item of equipment change its dimensions, its weight, its heat release or its clearances after the coordination drawing is reviewed, the Contractor shall revise and resubmit the coordination drawing before the equipment is delivered.
NOTE A coordination drawing is the only document on which the working space, the dedicated space, the door swing, the egress path, the pads, the foreign systems and the circuit sources appear together at the equipment's real size, and it is the document a trade can be held to. A floor plan drawn before the shop drawings exist shows an equipment outline that the delivered equipment rarely matches. (16.6)

17 Field Verification

17.1 The Contractor shall verify and record the items indicated in the datasheet for each room, at the stage each item names, and shall transmit the record to the Engineer of Record before the equipment in the room is energized.
Field Verification of the Roomcheckbox
☑ Working space depth, width and height measured at every lineup after the equipment is set
☑ Dedicated electrical space clear of foreign systems before the ceiling is closed
☐ Clear height measured before the equipment is delivered
☑ Door swing, clear opening, panic hardware and free egress verified
☑ Illuminance measured at the working plane of every lineup
☐ Room air temperature held within the limits with the equipment loaded
☐ Ventilation airflow or cooling capacity measured against the calculation
☐ Floor drain, curb and drip shields verified where selected
☑ Receptacle location, source and GFCI operation verified
☐ Ground bar bonding verified
☑ Door signs installed and legible
17.2 The working space shall be measured with a tape from the as-set enclosure faces and recorded against the depth, width and height the datasheet basis requires, and any deficiency shall be corrected by relocating the obstruction, not by accepting the measured value.
17.3 The illuminance shall be measured with a calibrated meter on a vertical plane at the equipment face at the height of the device handles, with the room's normal lighting on and daylight excluded, and the measured value shall be not less than the datasheet value.
17.4 The room air temperature shall be measured at the intake of the equipment with the highest heat release, with the room's equipment carrying not less than the load available at the time of the verification and the ventilation or cooling in normal operation, and the trade responsible for the room's ventilation or cooling shall demonstrate by calculation from the measured values that the room holds the datasheet limits at the heat-release basis.
17.5 The ventilation airflow shall be measured under Testing Adjusting And BalancingTesting, Adjusting, and Balancing for HVACResolves to the current adopted revision.sync/testing-adjusting-and-balancing and the cooling unit capacity verified under the standard for that unit, and this standard requires only that the result be recorded against the room calculation.
17.6 Where a verification finds a deficiency, the Contractor shall correct it at no change in the contract sum and shall repeat the verification, and the cost of a repeat verification shall be borne by the Contractor.
17.7 The field verification of the room shall be folded into the total building commissioning program under CommissioningTotal Building CommissioningResolves to the current adopted revision.sync/commissioning where the project has one, and shall be performed under this standard where it does not.
NOTE The measurements this section requires are the ones an Authority Having Jurisdiction takes with a tape and a light meter on the day of the final inspection, and a room that fails one of them then is a room whose ceiling is reopened and whose duct is moved on the last week of the project. Taking them when the equipment is set, with the ceiling still open, is what makes them cheap. (17.8)

18 Protection of the Room During Construction

18.1 The electrical room shall not be used for the storage of construction materials, tools or the equipment of any trade, other than the electrical equipment that is set in its final position and the material needed to complete the room itself.
18.2 Electrical equipment delivered to a room before the room is enclosed and dry shall be protected from weather, dust and moisture as its own standard requires, and the space heaters of any equipment that has them shall be energized from a temporary source from the day the equipment is set.
18.3 No equipment with electronic components shall be set in a room until the room is enclosed, its roof or the floor above it is watertight, and the dust-producing work of the other trades in the room is complete.
18.4 The working space and the dedicated electrical space of every lineup shall be respected by every trade from the day the equipment is set, and no pipe, duct, hanger or finish that would later have to be removed to satisfy this standard shall be installed.
18.5 Where the room's permanent ventilation or cooling is not in service when the equipment is energized, temporary ventilation or cooling holding the datasheet limits shall be provided until it is.

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