Hello! I came across this today and I have not experienced it before. There was (two) 2 pole breakers connected togethor. The main panel (feeding the whole campus, a bunch of small buildings) is 120/240 1 phase 300Amp M.C.B.. The (two 2 pole breakers that are connected togethor) are feeding two seperate small buildings, those buildings panels have each their own 150A MCB interior panel that feeds its building. I verified that by turning this breaker off and those two separate buildings went off. my question is why they didnt use seperate two 150A breakers. Are they both sharing the 150Amps? See attached pictures. Any knowledge on this would be appreciated. Thank you
A two 2 pole breakers connected together?? and feeding two seperate panels
- Thread starter Cartoon1
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- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Common with square D because a single set of stabs cannot supply 150 amps.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
That is a single 2 pole 150A branch breaker.
I believe the QO plug on jaw is rated a maximum of 125A so Square D uses a factory assembly of (2) 2-pole housings to handle higher ampacities. Note how only one housing has printed information on it.
I believe the QO plug on jaw is rated a maximum of 125A so Square D uses a factory assembly of (2) 2-pole housings to handle higher ampacities. Note how only one housing has printed information on it.
Is that code compliant? If i wanted to add another breaker to this panel would i able to add another 150 or even a 200 amper with the same setup?
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
You're only limited by what the manufacturer says is the largest breaker that can be supplied by the connection to the bus stabs. If Sq D allows a 200 amp CB in this panel then you can use one.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
They had to make something that fits the space where other breakers mount that can handle the higher current.
Not as good of a chance of making some variant of one of these fit there.
Variants of that do exist for use in I-line panels though.
Not as good of a chance of making some variant of one of these fit there.
Variants of that do exist for use in I-line panels though.
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