Section 645.5/Information Technology Equipment Room Wiring
NEC 645.5 covers wiring requirements for information technology equipment (ITE) rooms including the critical branch disconnect, under-floor wiring, and HVAC shutdown provisions.
Information technology equipment (ITE) rooms that comply with Article 645 may use the special wiring provisions in Section 645.5 as an alternative to standard building wiring requirements. Section 645.5(A) requires a disconnecting means that disconnects all electronic equipment and HVAC serving the room. This disconnect must be located at the principal exit door and must be identified as the ITE room disconnect. Section 645.5(B) permits under-raised-floor wiring using listed cables (Type DP, plenum-rated cables) without conduit, provided the space under the raised floor is used exclusively for ITE wiring and HVAC supply. Power cables under the floor must be secured to prevent damage. Section 645.5(E) requires the HVAC system serving the ITE room to be equipped with smoke detection that shuts down the HVAC upon detection. Section 645.5(F) requires the room to be separated from other occupancies by fire-resistant-rated walls, floors, and ceilings with self-closing fire-rated doors. Only personnel with ITE responsibilities may have access to the room.
Why this section exists
Data centers and server rooms have unique electrical requirements: high power density, extensive cable routing under raised floors, and critical cooling systems. The principal exit disconnect allows emergency responders to quickly de-energize all equipment and HVAC in the room during a fire, preventing electrical hazards to firefighters. The under-floor wiring provisions allow the flexible cable routing needed for data centers without requiring every cable to be in conduit, which would be impractical for thousands of cables. The fire separation and smoke detection requirements protect the valuable equipment and contain fires within the ITE room. The HVAC shutdown prevents smoke distribution through the raised-floor plenum.
What plan reviewers look for
Plan reviewers check the electrical plan for the ITE room disconnect at the principal exit door and verify it disconnects all equipment power and HVAC. They check under-floor wiring for listed cable types. They verify smoke detection in the under-floor space and the HVAC shutdown connection. They check the architectural plans for the fire-rated room separation. They verify the room meets all the qualifying conditions in Section 645.4 (dedicated room, access control, fire separation). For battery backup systems in the ITE room, they verify compliance with Article 480.