Q. An existing corporate data center is concerned about possible loss of power due to the fact that it is supplied by only one service. The existing feed consists of a 1600A, 208Y/120V, 3-phase, four-wire service. Data center management personnel propose to add an additional service. What are the Code-compliant options available to the data center management team?

A) An additional service cannot be added; this is a violation of 225.30.

B) An additional service can only be added if the capacity requirements exceed 2000A.

C) An additional service can only be added if it is of different characteristics. For example, it is a single-phase, 240/120V, 3-wire service.

D) An additional service identical to the existing service may be installed for “enhanced reliability.”

Answer: D

Explanation: Per a change to 230.2(A)(6) of the 2005 NEC, an additional service per 230.2(A)(6) or an additional feeder per 220.30(A)(6) may be installed for the purpose of “enhanced reliability.” The additional service or feeder may be identical to the existing service or feeder.

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at necexpert@aol.com.