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Thursday, September 30, 2021

Question:

Hello and thanks for the NEC insight. If I install a 1000-ampere feeder to a switchboard in a commercial building, does the NEC require arc-energy reduction means for the feeder and connected switchboard? Bryce Pease
A

Answer:

Hello Bryce, Good question. There is information missing regarding the type of overcurrent protection intended for this installation. We will try to stick to the basics with the response. Section 240.67 addresses arc-energy reduction requirements if fuses are installed for overcurrent protection, and Section 240.87 addresses arc-energy reduction requirements if circuit breakers are used for overcurrent protection. At this time, the threshold is 1200 amperes or greater which necessitates the arc-energy reduction means. For breakers, in 240.87 the requirement applies to the highest continuous current trip setting. Typically 1000 amperes is achieved in an adjustable trip unit setting on device in a 1200 ampere frame. 

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