Article 645 of the 2017 Edition of the National Electrical Code (NEC) covers equipment, power supply wiring, equipment interconnecting wiring, and grounding (bonding) of information technology (IT) equipment and systems in IT equipment rooms.
Many other areas in the NEC apply to these rooms [Sec. 645.3(A) through (I)]. For example, the non-current-carrying conductive members of optical fiber cables within such a room must be bonded per Sec. 770.14 [645.3(C)]. And you’ll find sections of half a dozen other Articles referenced in Sec. 645.3(B)(1) through (6).
You can use Art. 645’s wiring methods instead of the wiring methods of Chapter 3 and Parts I and V of Art. 770, but only if you meet the conditions listed in Sec. 645.4(1) through (6).
Branch circuits supplying one or more units of IT equipment must have an ampacity of at least 125% of the total connected loads. If you run branch circuit supply conductors under a raised floor, you must install them per the requirements in Sec. 300.11. You must also use the wiring methods of Sec. 300.22(C) and/or the 17 wiring methods listed in Sec. 645.5(E)(1)(b)(1) through (17).
OCPDs supplying critical systems must be selectively coordinated [645.27] with all supply side OCPDs.
