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Code Q&A

Jul 23, 2004 6:34 PM, By Mike Holt

Q. Can a single transfer switch be used to supply both emergency and non-emergency loads, such as a UPS for telecom equipment?

A. No, a single transfer switch is not permitted to serve emergency and non-emergency loads [700.6(D)]. However, a single generator is permitted to serve emergency and non-emergency loads, provided multiple transfer switches are used, and automatic load shedding ensures adequate power for the emergency loads [700.5(B)] (Figure below).

The building feeder disconnecting means is permitted to be locked closed if there is concern that the opening of the readily accessible disconnect could result in a hazard to persons or property, lets say because of vandals or terrorism.

Got a Code question for Mike? Send it to him at mike@mikeholt.com.

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