What are the simple words required when the equipment in this room is rated over 600V? As per 110.34(C), Locked Rooms or Enclosures, the Code states, “The entrance to all buildings, vaults, rooms, or enclosures containing exposed live parts or exposed conductors operating at over 600V, nominal, shall be kept locked unless such entrances are under the observation of a qualified person at all times. Where the voltage exceeds 600 volts, nominal, permanent and conspicuous warning signs shall be provided, reading as follows: DANGER — HIGH VOLTAGE — KEEP OUT.”

This same phrase is also noted in sections 314.72(E), 490.53, 490.55, and 665.23 of the NEC.

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