1 Scope

NOTE This Standard covers the procurement of power distribution units (PDUs) and plug-in power devices that take a branch or feeder source and distribute it to plug-connected loads at the point of use. (1.1)

NOTE The term "PDU" carries two unrelated meanings in the construction trades, and this Standard fixes the meaning deliberately. (1.2)

NOTE In data center and IT contexts a PDU is a rack-mounted intelligent power strip listed under UL 1363A; to industrial and utility engineers the same letters name a large floor-standing switchboard-fed distribution assembly. This Standard governs the former (rack PDUs and plug-in devices) and uses "floor PDU" or "switchboard" for the latter, which is procured under PanelboardsPanelboardsResolves to the current edition.sync/panelboards. (1.2.1)

NOTE Two distinct listing families fall within this single specification scope. (1.3)

NOTE Rack-mount PDUs, relocatable power taps, and outlet strips are listed under UL 1363, UL 1363A, or UL 60601-1 and installed under NEC Article 645. (1.3.1)

NOTE Busway plug-in tap boxes (bus plugs) are listed under UL 857 and installed under NEC Article 368. (1.3.2)

NOTE Both families are the same product category from a procurement standpoint — a device that derives plug-connected branch power — and are specified together here, with sub-type requirements called out where the listings diverge. (1.3.3)

1.4 The Contractor shall furnish PDUs and plug-in devices complete with the cord sets, inlet and outlet connectors, integral overcurrent protection, metering or monitoring intelligence, and mounting hardware required for a complete and operable installation.

1.5 Where this Standard and the Contract Drawings conflict, the Contractor shall request clarification from the Engineer of Record before procurement.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.

2.2 Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

2.3 The 2023 edition of NFPA 70 (NEC) is the baseline for this Standard; the Contractor shall verify the edition adopted by the Authority Having Jurisdiction and comply with locally adopted amendments.

Standard	Title
NFPA 70 (NEC) Art. 368	Busways — plug-in busway and tap device installation, overcurrent protection, grounding, accessibility
NFPA 70 (NEC) Art. 645	Information Technology Equipment (645.4 room qualification, 645.14 derived systems, 645.17 branch-circuit sizing)
NFPA 70 (NEC) Art. 240	Overcurrent Protection (240.24(A)(1) busway plug-in accessibility per 368.17(C))
NFPA 70 (NEC) Art. 285	Surge-Protective Devices (where integral SPD is specified)
NFPA 70 (NEC) Art. 110	Requirements for Electrical Installations (110.10 short-circuit current rating)
NFPA 70 (NEC) Art. 210	Branch Circuits (210.19(A)(1), 210.20(A) continuous-load sizing)
NFPA 70E	Standard for Electrical Safety in the Workplace (arc flash and shock labeling)
NFPA 75	Standard for the Fire Protection of Information Technology Equipment
UL 857	Busways (low-voltage busway and plug-in units to 600 V)
UL 1363	Relocatable Power Taps
UL 1363A	Special Purpose Relocatable Power Taps (rack-mount PDUs for IT equipment assemblies)
UL 1449	Surge Protective Devices (integral surge suppression)
UL 60601-1	Medical Electrical Equipment (PDUs in patient care vicinities)
IEC 60320	Appliance Couplers for Household and Similar General Purposes (C13/C14, C19/C20)
NEMA WD 6	Wiring Devices — Dimensional Requirements (NEMA locking and straight-blade configurations)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following action submittals for the Engineer of Record's review before fabrication or ordering:

Product data for each PDU and plug-in device type: functional tier, form factor, input voltage and ampacity, inlet connector, outlet type and count, and listing category
Wiring diagrams showing phase configuration, internal overcurrent device arrangement, and outlet-to-breaker grouping
Short-circuit current rating (SCCR) for each device with the available fault current at the point of connection and supporting coordination
Cord set schedule: input cord length and connector, and any outlet cord-management provisions
For busway plug-in tap boxes: tap rating, enclosure type, engagement height, and overcurrent device coordination with the upstream busway feeder
For monitored, switched, or ATS units: network interface, management protocols, sensor ports, and firmware revision

Action submittals to be providedcheckbox

☐ Product data per device type

☐ Wiring and phase-configuration diagrams

☐ SCCR documentation with fault-current basis

☐ Cord set schedule

☐ Busway tap box rating and coordination (where applicable)

☐ Monitoring/management interface data (where applicable)

3.2 Closeout Submittals

3.2.1 The Contractor shall submit the following closeout submittals before Substantial Completion:

Manufacturer's installation, operation, and maintenance manuals for each device type
Factory test reports for the furnished units
Network configuration record for intelligent units: assigned IP addresses, device names, SNMP settings, and firmware revision as commissioned
Field test reports, including infrared thermography results at full load

Closeout submittals to be providedcheckbox

☐ Installation, operation, and maintenance manuals

☐ Factory test reports

☐ Network configuration record (intelligent units)

☐ Field test reports including IR thermography

3.3 Informational Submittals

3.3.1 The Contractor shall submit the following informational submittals for record:

Listing certificates for the applicable UL category of each device
Manufacturer's warranty documentation
Arc flash and shock hazard label proofs for busway tap boxes and switchboard-fed PDU input assemblies

Informational submittals to be providedcheckbox

☐ UL listing certificates

☐ Warranty documentation

☐ Arc flash / shock label proofs

4 Quality Assurance

4.1 Rack-mount PDUs, relocatable power taps, and outlet strips shall be listed and labeled under the applicable UL category: UL 1363A for rack-mount IT equipment PDUs, UL 1363 for standalone relocatable power taps, and UL 60601-1 for units in patient care vicinities.

4.2 Busway plug-in tap boxes shall be listed and labeled under UL 857.

4.3 Where an integral surge protective device is specified, that device shall be listed under UL 1449.

4.4 All units of a given type shall be the product of a single manufacturer.

4.5 The manufacturer shall have a minimum of five years of documented production experience with the specified device family.

4.6 Listing Selection

4.6.1 Select the listing category appropriate to the application; the wrong listing is a common cause of inspection and survey citations.

Required listing categoryradio

● UL 1363A special-purpose relocatable power tap (rack-mount IT PDU)

○ UL 1363 relocatable power tap (standalone outlet strip)

○ UL 60601-1 / hospital-grade (patient care vicinity)

○ UL 857 busway plug-in unit (bus plug)

5 Environmental and Service Conditions

5.1 PDUs and plug-in devices shall be rated for continuous operation under the service conditions at the installed location without derating below the specified load.

5.2 Rack-mount units shall be suitable for an operating ambient temperature of 0 to 50 °C and 0 to 95% relative humidity, non-condensing, consistent with the UL 1363A service environment.

5.3 Busway plug-in tap boxes installed in industrial environments shall be furnished in an enclosure rated for the area: NEMA 1 or 12 for indoor clean/dusty areas and NEMA 3R where exposed to moisture.

5.4 Where units are installed in an NEC Article 645 information technology equipment room, the room shall satisfy all conditions of NEC 645.4 before Article 645 wiring methods and equipment are used.

5.5 The Contractor shall verify that the room satisfies every condition of NEC 645.4 before applying Article 645 wiring methods; a 645-listed PDU installed in a non-qualifying room is a code violation.

NOTE A 645-listed PDU installed in a room that does not meet every condition of NEC 645.4 is a code violation; verifying only the equipment listing without confirming room qualification is a common field error. (5.5.1)

5.6 Operating Environment

5.6.1 Specify the installed environment so the enclosure rating and temperature qualification can be confirmed.

Installed environmentradio

● Conditioned data center / server room (NEC 645)

○ Commercial equipment closet

○ Industrial floor (busway tap-off)

○ Healthcare rack assembly / patient care vicinity

Busway tap box enclosure ratingradio

● NEMA 1 (indoor general purpose)

○ NEMA 12 (indoor dust-tight)

○ NEMA 3R (rainproof)

6 Functional Tier and Form Factor

NOTE The functional tier sets how much intelligence the unit carries; it is the first selection because it drives cost, network infrastructure, and the rest of the procurement. (6.1)

NOTE A basic unit only distributes power. A metered unit adds a local current display so a technician can read load at the rack. A monitored unit reports current, voltage, and power over the network for remote capacity management. A switched unit adds per-outlet remote on/off and reboot for lights-out operation. An ATS unit adds a second input and transfers between two independent feeds. (6.1.1)

6.2 The Contractor shall furnish PDUs of the functional tier specified for each rack position; tiers shall not be substituted downward.

6.3 Functional Tier

PDU functional tierradio

○ Basic (no metering)

○ Metered (local current display)

● Monitored (remote SNMP/web monitoring)

○ Switched (per-outlet remote control)

○ ATS (dual input, automatic transfer)

6.4 Form Factor

NOTE Horizontal 1U/2U units consume rack U-space but suit shallow or network racks; vertical 0U units mount in the rack's side channel and free U-space for equipment; floor units serve whole-row distribution; busway tap boxes feed equipment from overhead bus. (6.4.1)

6.4.2 The form factor shall match the rack design and the cabinet's cable-management scheme.

Mounting form factorradio

○ Horizontal 1U rackmount

○ Horizontal 2U rackmount

● Vertical 0U (side-mount)

○ Free-standing floor PDU

○ Plug-in busway tap box

7 Electrical Ratings

7.1 Input ratings shall be selected for the connected load with the continuous-load derating required by code, not for the nameplate ampacity.

7.2 The Contractor shall load each unit such that the continuous load does not exceed 80% of the input circuit rating, per NEC 210.19(A)(1) and 210.20(A).

NOTE A 30 A input PDU is loaded to a maximum of 24 A continuously. RFIs commonly arise when the field reads the 30 A nameplate and sizes loads to 30 A; the 80% ceiling is a code limit, not a margin to be reclaimed. (7.2.1)

7.3 The unit's short-circuit current rating shall equal or exceed the available fault current at the point of connection, per NEC 110.10.

7.4 The SCCR shall appear on the submittal with the fault-current basis stated.

NOTE SCCR is the single most-omitted line on PDU submittals and a frequent cause of AHJ rejection. (7.4.1)

7.5 Busway plug-in tap boxes shall be rated for the system voltage, up to 600 V AC maximum per UL 857; plug-in units above 600 V are outside this Standard.

7.6 Input Voltage and Ampacity

NOTE The most common configuration for data center racks is 208 V single-phase at 30 A (NEMA L6-30P inlet), delivering 24 A continuous. (7.6.1)

7.6.2 The input voltage of the plug-in unit shall be specified to match the connected load and the branch circuit serving the rack.

Input voltageradio

○ 120 V single-phase

● 208 V single-phase

○ 240 V single-phase

○ 208 V 3Φ wye (120/208 V)

○ 480 V 3Φ

7.6.3 The input circuit rating of the plug-in unit shall be specified to match the branch-circuit overcurrent protection serving the rack.

Input circuit ratingradio

○ 15 A

○ 20 A

● 30 A

○ 60 A

7.6.4 The phase configuration of the plug-in unit shall be specified to match the input voltage and branch circuit serving the rack.

Phase configurationradio

● Single-phase 2-wire

○ Single-phase 3-wire

○ 3Φ 4-wire wye (120/208 V)

○ 3Φ delta

7.7 Busway Tap Rating

NOTE Busway plug-in tap boxes are furnished across a wide ampacity span; select the standard rating that protects the tap conductors and matches the connected load. (7.7.1)

7.7.2 The busway plug-in tap rating shall be specified to protect the tap conductors and match the connected load.

Busway plug-in tap ratingselect

20 A

30 A

60 A

100 A

200 A

400 A

600 A

800 A

1200 A

7.7.3 The short-circuit current rating of the busway plug-in tap box shall be specified to withstand the available fault current at its point of connection.

Short-circuit current rating (SCCR)range

kAIC

10100

8 Connectors and Outlets

8.1 The inlet connector shall match the upstream branch circuit or busway tap and the unit's input rating.

NOTE Specifying a 15 A NEMA 5-15P inlet on a rack PDU feeding high-density servers leaves no headroom; data center units shall use a 20 A or 30 A inlet on a matched circuit. (8.1.1)

8.2 The Contractor shall furnish the inlet connector specified for each unit; locking configurations shall be used where retention is required.

8.3 Outlet quantity and the C13/C19 split shall be selected from the actual server power cord population, not assumed.

NOTE IEC C13 outlets are rated 10 A / 250 V per IEC 60320, de-rated for North American use under UL 1363A; C19 outlets are rated 16 A / 250 V IEC. Loads exceeding roughly 1.5 kW per outlet shall be served from C19 outlets. (8.3.1)

NOTE GPU-dense and high-draw racks need a higher C19 count; ordering the wrong C13/C19 ratio forces field re-procurement and schedule delay. The usual configuration for a 30 A 208 V unit is a 24-outlet mix of 16 x C13 and 8 x C19. (8.3.2)

8.4 Outlets in vibration-prone or high-traffic industrial environments shall provide cord retention, by IEC locking outlets or outlet retention clips, so friction-fit cords do not back out.

8.5 Healthcare rack assemblies in patient care vicinities shall use hospital-grade, green-dot outlets on units listed to UL 60601-1.

8.6 Input Connector

Input (inlet) connectorselect

NEMA 5-20P (120 V, 20 A)

NEMA L5-30P (120 V, 30 A locking)

NEMA L6-20P (208 V, 20 A locking)

NEMA L6-30P (208 V, 30 A locking)

NEMA L14-30P (120/240 V, 30 A locking)

NEMA L21-30P (208 V 3Φ, 30 A locking)

Hardwired

Busway tap-off

8.7 Outlet Mix

IEC C13 outlet countrange

outlets

042

IEC C19 outlet countrange

outlets

024

Additional NEMA outletsselect

None

NEMA 5-15R

NEMA 5-20R

Hospital-grade 5-20R (green dot)

Outlet retentionradio

● None (friction fit)

○ IEC locking outlets

○ Outlet retention clips

9 Overcurrent Protection

9.1 Integral overcurrent protection shall be coordinated with the upstream device so that a branch fault clears at the nearest protective device.

NOTE Rack PDUs may carry individual outlet-bank breakers, a single whole-unit breaker, or no integral device when the unit is cord-and-plug connected to an upstream branch breaker. Busway plug-in tap boxes carry either fusible or molded-case circuit-breaker protection sized to the tap. (9.1.1)

9.2 Busway plug-in tap box overcurrent devices shall be sized to protect the tap conductors per NEC 368.17.

NOTE Mismatched tap and feeder protection ratings generate RFIs at rough-in inspection; coordinate the tap device with the upstream busway feeder protection before ordering. (9.2.1)

9.3 Where the unit serves an NEC Article 645 IT room with a transformer-derived secondary, the secondary shall not be treated as a separately derived system for grounding, per NEC 645.14.

NOTE Running a separate grounding electrode conductor to a 645.14 derived secondary is incorrect and a common field error. (9.3.1)

9.4 Rack PDU Overcurrent Device

Integral overcurrent protection (rack PDU)radio

● Individual outlet-bank breakers

○ Whole-unit breaker only

○ None (protected by upstream branch OCPD)

9.5 Busway Tap Box Overcurrent Device

Busway tap box protectionradio

○ Fusible switch

● Molded-case circuit breaker

10 Monitoring and Network Interface

10.1 Metered, monitored, and switched units shall provide the management interface specified.

10.2 The project shall provision the supporting network infrastructure — management VLAN, allocated IP addresses, device naming convention, and SNMP settings — before energization.

NOTE A metered or monitored PDU ordered without a dedicated management VLAN, allocated IP addresses, a device naming convention, and SNMP settings becomes an unmonitored unit after installation — the most common reason intelligent PDUs deliver no value. (10.2.1)

10.3 Monitored and switched units shall communicate over 10/100 Base-T Ethernet.

10.4 Monitored and switched units shall support SNMP v3 and an HTTPS web interface.

10.5 Switched units shall provide per-outlet remote on/off and reboot, outlet grouping, and load-shedding capability.

10.6 Units provided with environmental sensor ports shall support temperature and humidity sensing for rack-level monitoring.

10.7 The Contractor shall configure each intelligent unit with the project's assigned address, device name, and SNMP credentials.

10.8 The Contractor shall record the configuration of each intelligent unit in the closeout submittal.

10.9 Network Interface

Management interfaceradio

○ None (basic unit)

○ Local display only (metered)

● Ethernet SNMP / HTTPS (monitored)

○ Ethernet SNMP / HTTPS with switching (switched)

Environmental sensor portradio

○ Not required

● Temperature only

○ Temperature and humidity

11 Construction and Finish

11.1 Enclosure and chassis materials shall suit the mounting form factor and environment.

NOTE Vertical 0U units are typically extruded-aluminum bodies; horizontal and floor units are typically formed steel. Powder-coat finishes suit data center and commercial environments; anodized aluminum suits the extruded vertical units. (11.1.1)

11.2 The unit chassis shall be furnished in the specified material and finish, free of sharp edges that could damage cords during installation.

11.3 Enclosure

Enclosure / chassis materialradio

○ Formed steel

● Extruded aluminum

Finishradio

● Powder coat - black

○ Powder coat - gray

○ Anodized aluminum

12 Cord Sets and Cable Management

12.1 Each cord-and-plug connected unit shall be furnished with an input cord of the specified length and connector; the cord shall reach the upstream receptacle without splices or extension.

12.1.1 The most common rack PDU input cord is 10 ft. Longer cords are special-order and shall be confirmed against the receptacle location before ordering.

12.2 For busway plug-in tap boxes, the supplied cord set or drop shall reach the served equipment from the engagement height without trip hazard or tension on the plug.

NOTE Bus plug faces sit roughly 10 to 14 ft above finished floor on industrial runs; an undersized drop pulls tension on the plug, and an oversized drop creates a trip hazard. Coordinate the engagement height with the drop length. (12.2.1)

12.3 Outlet cord-management features, where specified, shall retain server cords clear of adjacent equipment.

12.4 Cord Set

Input cord lengthselect

6 ft

10 ft

12 ft

15 ft

Outlet cord managementradio

● None

○ Cord-retention hooks

○ Locking outlet sleeves

12.5 Busway Tap Box Engagement

NOTE Where the engagement height is set by the busway elevation, indicate it on the drawings rather than fixing it here. (12.5.1)

12.5.2 The busway tap box engagement height shall be specified in feet above finished floor, or indicated on the drawings where governed by the busway elevation.

Busway tap box engagement heightrange

ft AFF

816

Per drawings — busway elevation (deferred by default)

13 Safety Labeling

13.1 Busway plug-in tap boxes and switchboard-fed PDU input assemblies shall carry arc flash and shock hazard labeling per NFPA 70E 130.5(H).

13.2 The Contractor shall furnish each busway tap box and switchboard-fed input assembly with arc flash and shock hazard labels showing the incident energy or PPE category, nominal voltage, and arc flash boundary.

NOTE Facility safety officers increasingly enforce NFPA 70E labeling at acceptance; missing labels delay closeout. (13.2.1)

14 Testing

14.1 Each rack-mount PDU shall be factory tested per UL 1363A for dielectric strength, grounding continuity, leakage current, and overcurrent device trip.

14.2 Leakage current for non-healthcare rack PDUs shall not exceed 0.5 mA; units in patient care vicinities shall not exceed 100 µA per UL 60601-1.

14.3 Each busway plug-in tap box shall be factory tested per UL 857, including dielectric (hi-pot) test, contact resistance, and temperature-rise test at rated current.

14.4 Busway plug-in units shall pass a mechanical engagement and withdrawal cycle test of not fewer than 100 operations.

14.5 After installation, the Contractor shall perform infrared thermography on each busway tap box and each hardwired PDU input termination at full load and shall record any connection exceeding the manufacturer's temperature limit for correction.

14.6 Intelligent units shall be functionally tested after configuration for SNMP trap generation, outlet switching (switched units), and sensor reading.

14.7 Field Test Requirements

Field testing to be performedcheckbox

☑ IR thermography at full load

☑ Grounding continuity verification

☐ Intelligent unit functional test (SNMP / switching / sensors)

☐ ATS transfer test (dual-input units)

15 Installation

15.1 Units shall be installed in accordance with the manufacturer's instructions and the applicable NEC article for the device family.

15.2 Rack-mount units shall be secured to the rack with the manufacturer's mounting hardware so the unit and its cords bear no load on the outlets.

15.3 Vertical 0U units shall be mounted in the cabinet side channel so as not to obstruct equipment cable routing or airflow.

15.4 Busway plug-in tap boxes shall be engaged onto the busway only with the busway de-energized unless the unit and busway are listed for energized insertion, and shall be fully seated and latched before energization.

15.5 Overhead busway plug-in units not accessible from the floor shall be installed per NEC 368.17(C) and 240.24(A)(1), with a means of operating the disconnect from the floor where required.

15.6 Intelligent units shall be connected to the management network and configured before the racks they serve are placed in service.

16 Delivery, Storage, and Handling

16.1 Units shall be delivered in the manufacturer's original packaging, labeled with the model designation, ratings, and listing.

16.2 Units shall be stored indoors in a clean, dry location within the manufacturer's storage temperature range of -20 to 60 °C until installation.

16.3 Cords and connectors shall be protected from crushing and abrasion during storage and handling.

17 Warranty

17.1 The manufacturer shall warrant each PDU and plug-in device against defects in materials and workmanship for the period specified, measured from the date of Substantial Completion.

17.2 Warranty Period

Manufacturer warranty periodradio

○ 2 years

● 3 years

○ 5 years

18 Spare Parts

18.1 The Contractor shall furnish the spare parts specified below for owner stock, in the manufacturer's original packaging and labeled with the device type they serve.

Spare parts to be furnishedcheckbox

☐ Spare input cord sets

☐ Spare environmental sensors

☐ Spare outlet retention clips

☐ Spare fuses (busway tap boxes)