As of 2014, section 646.2 of the National Electrical Code defines Modular Data Centers as “prefabricated units, 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 distribution equipment, HVAC systems, and the like.” While MDCs must comply with all of Article 646, some requirements present design and inspection challenges.

Some challenges to consider come from Section 646.7 and Section 646.13. Section 646.7 calls for short-circuit ratings while Section 646.13 requires that integral parts of the MDC, such as lighting, control, power, HVAC, emergency lighting, and alarm circuits, comply with the requirements for their use and installation as well as be listed and labeled. Furthermore, the lighting requirements of Part III and the working space requirements of Part IV should be accounted for when designing and installing an MDC. One last stipulation to consider is that MDCs are pre-fabricated and often installed materials. Wiring and equipment are concealed and not easily accessible to inspectors at the final installation site. Because not all of the installation is open and available for inspection, the Authority Having Jurisdiction may be prevented from approving the installation as required by Section 90.4 and 110.2.

For more information about code compliance and MDCs, please download the full article.