Article 646 Modular Data Centers.

Modular data center.
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Modular data center.

Code Change Summary: A new article was added to provide rules on modular data centers.

Article 646 is new in the 2014 NEC® and provides rules on the use and installation of modular data centers (MDC). A MDC is a prefabricated unit, rated 600 volts or less, consisting of an outer enclosure, housing multiple racks or cabinets of information technology equipment and various support equipment, such as electrical service and distribution equipment, HVAC systems, and the like.

A MDC can consist of a shipping container, trailer, or other modular building, loaded with information technology equipment, servers and data center computers, then configured with cooling and power systems. When a facility needs to add data capacity, the new container is driven out to the data center and plugged into the existing facilities power and data systems, quickly bringing the extra capacity online.

Below is a preview of the NEC®.  See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).

Here is a brief glimpse of a few code sections in the new Article 646:

2014 Code Language:

646.4 Applicable Requirements. All MDCs shall:

(1) Be listed and labeled and comply with 646.3(N) and 646.5 through 646.9, or

Informational Note: One way to determine applicable listing requirements is to refer to UL Subject 2755, Outline of Investigation for Modular Data Centers.

(2) Comply with the provisions of this article.

646.6 Supply Conductors and Overcurrent Protection.

(A) Size. The size of the supply conductor shall be such as to have an ampacity not less than 125 percent of the full load current rating.

646.22 Workspace for Routine Service and Maintenance.

Workspace shall be provided to facilitate routine servicing and maintenance (those tasks involving operations that can be accomplished by employees and where extensive disassembly of equipment is not required). Routine servicing and maintenance shall be able to be performed without exposing the worker to a risk of electric shock or personal injury.

Informational Note: An example of such routine maintenance is cleaning or replacing an air filter.

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Article 646 Modular Data Centers.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is true of a modular data center?

A: Working space is required for those changing an air filter in a modular data center.
B: Supply conductors feeding a modular data center must be rated at least 100% of the full load current rating.
C: Supply conductors feeding a modular data center cannot be rated higher than 100% of the full load current rating.
D: Working space is not required in a modular data center.
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