Article 646 Modular Data Centers
Informational Note No. 1: Modular data centers include the installed information technology equipment (ITE) and support equipment, electrical supply and distribution, wiring and protection. working space, grounding, HVAC, and the like, that are located in an equipment enclosure.
Informational Note No. 2: For further information, see NFPA 75-2017, Standard for the Protection of Information Technology Equipment, which covers the requirements for the protection of information technology equipment and systems in an information technology equipment room.
Modular Data Center (MDC). Prefabricated units, rated 1000 volts or less, consisting of an outer enclosure housing multiple racks or cabinets of information technology equipment (ITE) (e.g., servers) and various support equipment, such as electrical service and distribution equipment, HVAC systems, and the like.
Informational Note No. 1: A typical construction may use a standard ISO shipping container or other structure as the outer enclosure, racks or cabinets of ITE, service-entrance equipment and power distribution components, power storage such as a UPS, and an air or liquid cooling system. Modular data centers are intended for fixed installation, either indoors or outdoors, based on their construction and resistance to environmental conditions. MDCs can be configured as an all-in-one system housed in a single equipment enclosure or as a system with the support equipment housed in separate equipment enclosures.
Informational Note No. 2: For information on listing requirements for both information technology equipment and communications equipment contained within a modular data center, see UL 60950-1-2014, Information Technology Equipment — Safety — Part. 1: General Requirements, and UL 62368-1-2012, Audio/Video, Information and Communication Technology Equipment — Part 1: Safety Requirements.
Informational Note No. 3: Modular data centers as defined in this article are sometimes referred to as containerized data centers.
Informational Note No. 4: Equipment enclosures housing only support equipment (e.g., HVAC or power distribution equipment) that are not part of a specific modular data center are not considered a modular data center as defined in this article.
- Wiring methods: 300.22(C)(1)
- Class 2, Class 3, and PLTC cables: 725.135(C), and Table 725.154
- Fire alarm systems: 760.53(B)(2), 760.135(C), and Table 760.154
- Optical fiber cables: 770.113(C) and Table 770.154(a)
- Communications circuits: 800.113 and Table 800.154(a)
- CATV and radio distribution systems: 800.113 and Table 800.154(a)
- Unless modified elsewhere in this article, wiring methods and materials for power distribution shall comply with Chapter 3. Wiring shall be suitable for its use and installation and shall be listed and labeled.
- The following wiring methods shall not be permitted:
- Wiring in areas under a raised floor that are constructed and used for ventilation as described in 645.5(E) shall be permitted to use the wiring methods described in 645.5(E) if the conditions of 645.4 are met.
- Installation of wiring for remote-control, signaling, and power-limited circuits shall comply with Part III of Article 725.
- Installation of optical fiber cables shall comply with Part V of Article 770.
- Alternate wiring methods as permitted by Article 645 shall be permitted for MDCs, provided that all of the conditions of 645.4 are met.
- Supply voltage, number of phases, frequency, and full-load current. The full-load current shown on the nameplate shall not be less than the sum of the full-load currents required for all motors and other equipment that may be in operation at the same time under normal conditions of use. Where unusual type loads, duty cycles, and so forth, require oversized conductors or permit reduced-size conductors, the required capacity shall be included in the marked full-load current. Where more than one incoming supply circuit is to be provided, the nameplate shall state the preceding information for each circuit.
Informational Note No. 2: For listed equipment, the full-load current shown on the nameplate may be the maximum, measured, 15-minute, average full-load current.
- For MDCs powered by a separate service, the short-circuit current rating of the service equipment provided as part of the MDC.
Informational Note: This rating may be part of the service equipment marking.
- For MDCs powered by a separate service, if the required service as determined by Parts III and IV of Article 220 is less than the rating of the service panel used, the required service shall be included on the nameplate.
Informational Note: Branch circuits supplying ITE loads are assumed to be loaded not less than 80 percent of the branch-circuit rating with a 100 percent duty cycle. As an alternative to the feeder and service load calculations required by Parts III and IV of Article 220, feeder and service load calculations for new, future, or existing loads may be permitted to be used if performed by qualified persons under engineering supervision.
- Electrical diagram number(s) or the number of the index to the electrical drawings.
- For MDC equipment enclosures that are not powered by a separate service, feeder, or branch circuit, a reference to the powering equipment.
- Manufacturer's name or trademark.
- The overcurrent protection shall consist of a single circuit breaker or set of fuses.
- The MDC shall be marked "OVERCURRENT PROTECTION PROVIDED AT MDC SUPPLY TERMINALS."
- The supply conductors shall be considered either as feeders or as taps and be provided with overcurrent protection complying with 240.21.
Modular data center equipment enclosures, powered from a separate MDC system enclosure that is part of the specific MDC system, shall have a short-circuit current rating coordinated with the powering module in accordance with 110.10.
Informational Note: One example of flexible power cord usage for connections between equipment enclosures of an MDC system is between an MDC enclosure containing only servers and one containing power distribution equipment.