I'm looking at NQ square D panels and from my understanding is that you can do a limited amount of sub-feed breaker in them. I have a 400A main circuit breaker and i also need to add another 300A breaker in it. It says that the number of subfeeds for NQMB6PPL allowed is 1. Does that mean the Main breaker + 1? which in my case is the 400A and the 300A? Does the main circuit breaker count as 1? I dont think it does, but i just want to make sure. Thank you
NQ Square D panel boards Sub-feed breaker
- Thread starter Cartoon1
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- Wisconsin
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- PE (Retired) - Power Systems
A sub feed breaker would be in addition to the main device.
Knightryder12
Senior Member
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- Clearwater, FL - USA
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- Sr. Electrical Designer/Project Manager
You have to be careful because some of those Sq D panels only allow for a 225a max sub feed breaker.
kwired
Electron manager
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- NE Nebraska
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- EC
I think largest plug on breaker is 200 amp in 2 pole versions and largest three pole bolt on is 150 amp.
I think maximum number of those larger breakers (the ones needing 2 spaces per pole) allowed in a panel isn't so much because of amp ratings but rather because of space needed for conductors.
Amp wise there really shouldn't be any limitation as long as total load doesn't overload the main breaker/feeder breaker.
Note there is sub feed lug kits - that have no switch or overcurrent device - just an assembly that extends the bus, if less conductor than the supply side feeder then feeder tap rule will apply to conductor connected here.
There is also feed through lug options, usually does require longer cabinet to use them though and would be ordered that way on initial purchase. Those also basically an extension of the bus and feeder tap rule applies if not full size conductor per the main breaker/feeder OCPD.
Yes correct, the options are either 2 225A or 1 400A
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I didn't pay close enough attention when first read the OP.
The NQMB6PPL you mentioned in OP is an adapter kit with rail extensions, dead front for this section of the assembled panel and hardware needed to install it. It is for either end of 400-600 amp bus sections for connecting bus to a 400 to 600 amp breaker which can be a main breaker or a sub feed breaker. You are limited to using two of these in any assembled panel because there is only two ends to the bus. The rest of the NQ bus is limited to attaching QO or QOB type breakers, how many of those breakers can be used will depend on length of the bus.
The NQMB6PPL you mentioned in OP is an adapter kit with rail extensions, dead front for this section of the assembled panel and hardware needed to install it. It is for either end of 400-600 amp bus sections for connecting bus to a 400 to 600 amp breaker which can be a main breaker or a sub feed breaker. You are limited to using two of these in any assembled panel because there is only two ends to the bus. The rest of the NQ bus is limited to attaching QO or QOB type breakers, how many of those breakers can be used will depend on length of the bus.
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