(C) Wiring Requirements
(a) Raceways, cables, or enclosures of the life safety and critical branch shall be readily identified as a component of the essential electrical system (EES). Boxes and enclosures (including transfer switches, generators, and power panels) shall be field- or factory-marked and identified as a component of the EES. Raceways and cables shall be field- or factory-marked as a component of the EES at intervals not to exceed 7.6 m (25 ft).
(b) Conductors of the life safety branch or critical branch shall not enter the same raceways, boxes, or cabinets with each other or any other wiring system. It shall be permitted for the branch conductors to occupy common equipment, raceways, boxes, or cabinets of other circuits not part of the life safety branch and critical branch where such wiring complies with one of the following:
- Is in transfer equipment enclosures
- Is in exit or emergency luminaires supplied from two sources
- Is in a common junction box attached to exit or emergency luminaires supplied from two sources
- Is for two or more circuits supplied from the same branch and same transfer switch
(d) Where Category 2 (general care) locations are served from two separate transfer switches on the essential electrical system in accordance with 517.18(A), Exception No. 3, the Category 2 (general care) circuits from the two separate systems shall be kept independent of each other.
(e) Where Category 1 (critical care) locations are served from two separate transfer switches on the essential electrical system in accordance with 517.19(A), Exception No. 2, the critical care circuits from the two separate systems shall be kept independent of each other.
- Nonflexible metal raceways, Type MI cable, Type RTRC marked with the suffix -XW, or Schedule 80 PVC conduit. Nonmetallic raceways shall not be used for branch circuits that supply patient care areas.
- Where encased in not less than 50 mm (2 in.) of concrete, Schedule 40 PVC conduit, flexible nonmetallic or jacketed metallic raceways, or jacketed metallic cable assemblies listed for installation in concrete. Nonmetallic raceways shall not be used for branch circuits that supply patient care areas.
- Listed flexible metal raceways and listed metal sheathed cable assemblies in any of the following:
- Where used in listed prefabricated medical headwalls
- In listed office furnishings
- Where fished into existing walls or ceilings, not otherwise accessible and not subject to physical damage
- Where necessary for flexible connection to equipment
- For equipment that requires a flexible connection due to movement, vibration, or operation
- Luminaires installed in ceiling structures
- Flexible power cords of appliances or other utilization equipment connected to the emergency system.
- Cables for Class 2 or Class 3 systems permitted by Part VI of this article, with or without raceways.