Arc Flash Protection for Switchgears, MCCs

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Charz

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I have heard that Arc flash protection is to be provided only at the Incoming breaker. What type of protection is provided at the Incoming breaker? Any Protection relay which includes the arc flash protection feature?
 
240.87 Arc Energy Reduction for breakers 1200 amps and larger. The methods to provide arc energy reduction are in 240.87(B)
 
But "is to be provided only at the Incoming breaker " would be incorrect though. It is ALLOWED to have only the main incoming breaker capable of arc energy reduction (a.k.a. "Maintenance Mode"), but that is not the ONLY way to accomplish arc flash protection of switchgear and MCCs.
 
For an MCC with Main Breaker is it even possible to provide arc flash reduction since MCB is not credited for arc-flash circuit interruption (on standard MCC)? Does Incoming breaker mean an upstream feeder breaker?
 
nhee2 said:
For an MCC with Main Breaker is it even possible to provide arc flash reduction since MCB is not credited for arc-flash circuit interruption (on standard MCC)? Does Incoming breaker mean an upstream feeder breaker?
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It depends on the manufacturer. I believe Schneider Electric considers their Model 6 mcc 1200A and larger main breaker to be sufficiently isolated for arc flash reduction.
 
It depends on the breaker. “Maintenance Mode” operation is an optional feature on many breakers now. You can get that option fir sure on A-B, Eaton, Siemens and Schneider MCCs that I know of. Not sure what’s happening with GE since being bought by ABB, but I know ABB offers a Maintenance Mode breaker so if they don’t have it yet, it’s only a matter of time.
 
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