Can a Branch Circuit Breaker Serve as the Main OCPD for a Power Panel? Article 408.36 (NEC 2020+)

[victor.cherkashi]

I am not sure if the following installation is in code compliance.

Details:
A. 300A fused disconnect on vertical busduct feeds 300A feeder in trough (277/480V system).
B. 70A tap conductors connect to this 300A feeder.
C. Tap conductors land on 70A branch breaker in Panel HV-1.
D. Panel HV-1 is main lug type with 100A bus rating.

My question: Can this 70A branch circuit breaker properly serve as the main OCPD for the panel?

Looking for code clarification and practical experience. Thanks.

Picture are attached for visualization.

 

[Jraef]

The definition of a “branch” OCPD is that it is the LAST protective device before the load. So if it is not, then it’s a feeder.

 

[LarryFine]

Yes, if fitted with a hold-down device; bolt-ins may not need one.

 

[infinity]

My question: Can this 70A branch circuit breaker properly serve as the main OCPD for the panel?

So the 70 amp CB is fed from a tap? If so as long as the conductors are rated for at least 70 amps it's code compliant. Type BQD is a bolt-on breaker so it can be back fed without an additional fasteners.

 

[jaggedben]

No violation I see (other than that the main breaker doesn't appear properly labeled, 110.22 and 408.4).

 

[norcal]

Yes, if fitted with a hold-down device; bolt-ins may not need one.

Only plug-in breakers require the hold down on back fed mains.