National Electrical Installation Standards

Standards as High as Your Own

Monday, August 12, 2019


Hi Charlie,

in an ambulatory surgery center operating room, are all electrical outlets, or all emergency electrical outlets required to be attached to a line isolation monitor? If some are connected a different panel, not in the room, must they have a means to see a fault/alarm in the room? how are non-emergency outlets involved? 

Christopher Walters


Hey Christopher thanks for your question. Line isolation monitors are only required for isolated power systems as stated in 517.160 (B). If they are used a green signal lamp must be conspicuously visible to persons in each area served by the isolated power system also stated in 517.160 (B). Isolated power systems are allowed to be used in critical care  spaces as stated in 517.19(F) and wet procedure locations as stated in 517.20(A). If isolated power systems are not used the monitors are not required.

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