Electrical

Standards

• Arc-Flash Study

  The arc-flash study for a project's electrical power distribution system: the incident energy and the arc-flash boundary at every bus a worker examines, adjusts, services, or maintains while it is energized, on AC systems from 208 V through 38 kV with utility, generator, inverter-based, and paralleled sources, and on the DC side of battery, energy storage, and photovoltaic equipment where the project includes it. Covers who performs the study and when it is issued, the IEEE 1584-2018 method and the methods applied outside its range, the buses studied, the source operating cases and the maintenance-mode cases, the arcing current variation, the clearing time taken from the accepted coordination settings, the arc-flash input data the system model does not already carry (electrode configuration, enclosure dimensions, bus gap, working distance), the content of the arc-flash label, the PPE arc rating the facility's safety program consumes, the mitigation recommendations, the report, and the five-year review and the events that call for a re-study.

• Automatic Transfer Switches

  Automatic transfer switches rated 1000 V and below, listed to UL 1008, that move a load between a normal source and an alternate source without operator action. Covers the switching mechanism, transition type, bypass-isolation construction, neutral treatment, the controller and its sensing, time delays, exerciser, load management and communications provisions, ratings including withstand and closing and short-time ratings, service-entrance construction, enclosures, identification, factory and field testing, installation, warranty, and spare parts, for switches serving emergency, legally required standby, optional standby, critical operations, and health care essential electrical system loads.

• Concrete Equipment Pads

  Cast-in-place concrete equipment pads and housekeeping pads that receive mechanical, electrical, and plumbing equipment - generators, pad-mounted and dry-type transformers, switchgear and switchboard lineups, chillers, air handlers, condensing units, pumps, compressors, boilers, and similar equipment - whether the pad bears on grade, on an interior finished floor, on a structural slab, or on an exterior platform. Covers the decisions a pad standard actually owns: pad geometry and height, attachment to the supporting concrete, reinforcement method, cast-in and post-installed equipment anchorage, cast-in raceway and grounding provisions, liquid containment, surface finish and grout bed, isolation from adjacent construction, dimensional and anchorage tolerances, and the verification performed before concrete is placed and before equipment is set.

• Conductors and Cables

  Building wire and cable for power, lighting, branch circuit, and feeder applications rated 600V and below in commercial, institutional, and industrial buildings. Covers single conductors installed in raceways and cable tray, Type MC metal-clad cable, and Type AC armored cable; conductor materials (copper and aluminum); insulation types (THHN/THWN-2, XHHW-2, RHW-2, USE-2); ampacity selection and derating; voltage drop; color coding and conductor identification; splicing, connectors, and terminations; pulling and installation; insulation resistance testing; and field acceptance.

• Distribution Transformers (Superseded)

  never for new adoptions — this standard has been split and superseded. For dry-type transformers rated 600 V and below use Low Voltage Dry Type Transformers; for transformers with a primary above 600 V (liquid-immersed pad-mounted and MV dry-type) use Medium Voltage Transformers.

• Electrical Equipment Labels

  The labels, nameplates, directories and signs applied in the field to the enclosures of electrical equipment rated 1000 V and below, and of the medium-voltage equipment on the same project: switchgear, switchboards, panelboards, motor control centers, transformers, transfer switches, generators, drives, disconnects, starters, busway, meter enclosures and control enclosures. Covers the equipment identification nameplate with its designation and source, the nameplates on each device and compartment, the circuit directory, the warning and danger signs NFPA 70 requires on equipment for voltage, multiple sources, disconnect location, back-fed devices, series ratings and ungrounded systems, the arc-flash warning label as a product and its installation, the available fault current marking, service equipment signs, the marking of emergency and standby system equipment, nameplate material, colors, character heights and attachment, the ANSI Z535.4 format of safety signs, installation, warranty and spare stock.

• Electrical Rooms

  The dedicated indoor electrical room and the electrical closet as a space: the room that houses service equipment, switchgear, switchboards, panelboards, motor control centers, dry-type transformers, transfer switches, drives, UPS modules, control-power batteries and the open or paralleling generator sets installed indoors. Covers the working space and the dedicated electrical space the adopted electrical code requires about the equipment, headroom, the number of entrances, door swing, clear opening and panic hardware, locking and free egress, the fire-resistance rating of the enclosing construction where a code sets one, the exclusion of piping and ductwork foreign to the electrical installation, water protection at the door and on the floor, the heat-release basis and the ventilation or cooling performance the room has to deliver, the temperature and humidity limits taken from the equipment ratings, illumination and emergency illumination of the working space, the convenience receptacle, housekeeping pad provision, floor finish, the room ground bar, the signs on the room door, the coordination drawing that proves every clearance before the room is framed, and the field verification before the room is closed in and before equipment is set.

• Engine Generators

  Packaged stationary engine-generator sets rated 1000 V and below, listed to UL 2200, furnished as the alternate source for emergency, legally required standby, optional standby, and critical operations loads, and sets the project applies as a prime or continuous source. Covers the engine and its fuel requirements by fuel type, the alternator and its excitation, the governor and voltage regulator, the set-mounted controller and the remote annunciator, the main line circuit breaker and the neutral bonding at the set, the cooling system, the fuel system on the skid including the sub-base tank, the exhaust silencer and aftertreatment, the enclosure and its sound attenuation, the starting batteries and charger, vibration isolation and seismic certification, factory and field testing, installation, warranty, and spare parts.

• Grounding and Bonding for Electrical Systems

  The grounding and bonding of electrical systems rated 1000 V and below in commercial, institutional, industrial, and water and wastewater facilities: the grounding electrode system and each of its electrodes (concrete-encased, ground ring, rod, pipe and plate, structural metal, metal water pipe, electrolytic), the soil basis the electrode design rests on, the grounding electrode conductor and its routing, the service grounding including the main bonding jumper, the bonding of service raceways and the intersystem bonding termination, the grounding and bonding of every separately derived system, the equipment grounding conductors of feeders and branch circuits and the rules that size them, isolated-ground circuits, the bonding of metallic piping, structural metal and other metal systems, the common bond to the lightning protection, telecommunications and cathodically protected systems, the grounding of direct-current control systems, ground bars, exothermic, compression and mechanical connections, and the field tests that prove the installed system. Every equipment standard in the corpus hands the equipment grounding and bonding of its equipment to this standard.

• Industrial Control Panels

  Factory-fabricated industrial control panels and enclosures that house instrumentation and controls (I&C) equipment for industrial, process, and water/wastewater (WTP/WWTP) facilities. Covers UL 508A listed control panels and enclosures housing programmable logic controllers, remote I/O, control relays, power supplies, network switches, and operator interface devices, rated 1000V and below. Addresses enclosure type rating selection (UL/NEMA Type 1, 3R, 4, 4X, 12), short-circuit current rating (SCCR) determination per UL 508A Supplement SB and NEC Article 409, enclosure sizing and component layout, internal power distribution and control power transformers, power-versus-signal wiring segregation, wire and terminal-block identification, thermal management, grounding and bonding, nameplates, and arc-flash labeling.

• Low Voltage Panelboards (Superseded)

  never for new adoptions — this standard has been merged into Panelboards, which carries its full content under the simple name.

• Low Voltage Switchboards

  Dead-front, floor-standing distribution switchboards rated 1000 V and below, listed to UL 891 and built to NEMA PB 2, in which molded-case or insulated-case circuit breakers, fusible switches, or bolted-pressure switches are group-mounted or individually mounted on a common bus, whether installed as service equipment or downstream of a transformer, switchgear, or another switchboard. Covers the ratings, the interrupting rating basis, the main and feeder devices and their trip units, the bus, the structure and enclosure, arc-flash mitigation, the service entrance, surge protection, metering and communications provisions built into the assembly, identification, factory and field testing, installation, warranty, and spares, for three-phase and single-phase AC systems in indoor and outdoor locations.

• Motor Control Centers

  Factory-assembled, floor-standing low-voltage motor control centers rated 600 V and below, listed to UL 845 and built to NEMA ICS 18, in which combination motor starter units, reduced-voltage starter units, variable frequency drive units, feeder units, control power units, and metering units plug onto a common vertical bus fed from a common horizontal bus. Covers the assembly ratings, the enclosure and structure, the bus, the wiring class and type, arc-flash mitigation, the unit construction and the devices inside each unit, communications, identification, factory and field testing, installation, warranty, and spares, for indoor and outdoor installations.

• Protective Device Coordination Study

  The time-current coordination study for a project's electrical power distribution system, from the utility's protective device at the point of delivery through every overcurrent protective device within the extent the datasheet selects, on AC systems rated 1000 V and below through 38 kV with utility, generator, inverter-based, and paralleled sources. Covers who performs the study and when it is delivered, the degree of coordination applied to normal distribution and the circuits on which NFPA 70 620.62, 645.27, 700.32, 701.32, 708.54, and 517.31(G) require selective coordination, the coordination time intervals and band separations, the curves of the utility device, transformers, motors, conductors, generators, and inverter-based sources that bound every setting, the coordination of ground-fault protection including the two levels NFPA 70 517.17 requires, the recommended setting of every trip unit, relay, fuse, and overload relay, the trade-off between selectivity and incident energy, the coordination deficiencies and who accepts them, the settings record handed to the field, the report, and the events that call for a re-study.

• Raceways and Conduit

  Conduit, tubing, and raceway systems that enclose and protect electrical power, lighting, and signaling conductors in commercial, institutional, and industrial buildings — including rigid metal conduit, intermediate metal conduit, electrical metallic tubing, flexible conduits, rigid PVC conduit, surface raceways, metal and nonmetallic wireways, and conduit fittings, boxes, and supports. Covers indoor and outdoor, exposed and concealed, wet and dry, and direct-burial raceway routing for branch circuits and feeders rated 1000V and below.

• Short-Circuit Study

  The short-circuit study for a project's electrical power distribution system, from the utility point of delivery through every point at which an interrupting rating, a close-and-latch rating, a short-time withstand rating, a bus bracing rating, or a marked short-circuit current rating is confirmed, on AC systems rated 1000 V and below through 38 kV with utility, generator, inverter-based, and paralleled sources. Covers who performs the study and when it is delivered, the calculation method and the duty networks, the fault types and the maximum and minimum cases, the system model and the data it is built from (the utility's available fault current and X/R, transformer impedances, conductor impedances and lengths, motor and generator contribution, inverter-based sources, and the survey of existing equipment on a renovation), the source operating cases, the equipment duty evaluation, the treatment of series-rated combinations, the available fault current and date that NFPA 70 110.24 requires at the service equipment, the report and the model handed to the coordination and arc-flash studies, and the events that call for a re-study.

• Site Utilities

  Exterior underground wet and dry site utilities for commercial, institutional, and industrial building projects, beginning 5 feet outside the building footprint and extending to the point of connection at the public main, meter, or utility owner's facility. Covers the site domestic and fire water service and on-site water distribution (ductile iron and PVC pressure pipe, valves, hydrants, service fittings, thrust restraint), the site sanitary sewer (gravity collection mains and laterals, and pressurized force mains and low-pressure sewer), and the underground dry-utility infrastructure for electrical and telecommunications service (direct-buried and concrete-encased duct banks, conduit, and manholes/handholes). Also covers the common trenching, bedding, embedment, backfill, separation, tracer-wire and marking-tape locating, pressure and leakage testing, deflection and air testing, and water-main disinfection that apply across these systems.

• Wiring Devices

  The receptacles, snap switches, wall-box dimmers, wall-box occupancy and vacancy sensors, and wall plates installed in outlet boxes on branch circuits rated 250 V and below and 60 A and below, in commercial, institutional, industrial, multifamily, and residential buildings. Covers device grade, the ampere rating and NEMA WD 6 configuration of receptacles, hospital-grade, isolated-ground, controlled, USB, surge-protective, locking, and special-purpose receptacles, the ground-fault and arc-fault devices installed at the outlet, tamper-resistant and weather-resistant devices and their covers, switch types and ratings, stand-alone dimmers and sensors with no connection to a control system, device color and plate material and finish, mounting height and orientation, terminations, device identification, field testing, warranty, and spares.

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