When it comes to residential wire size, does the rating matter for the main breaker or the bussbar rating?

S

sparkygbninja

Member
Location
Ca
Occupation
Journeyman electrician c10 contractor
Hello i have a situation where, im doing a penl upgrade. Its a 200 amp panel with a 225 amp bussbar.

I know 200 amp would be 2/0 covering 195 amps, but for the bussbar I would need 3/0 which covers 225 amps.

How do I choose the right size wire?
I know the nec table but then the 83 percent rule. I had an inspector speak to me about it, but still want to make sure for myself.

Does the rating go off of the main breaker or buss bar?
 
The main breaker is protecting the bus bar so the bus bar can have an ampacity that is greater than the size of the main OCPD just not less than the OCPD size.
 
infinity said:
The main breaker is protecting the bus bar so the bus bar can have an ampacity that is greater than the size of the main OCPD just not less than the OCPD size.
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Ok thank you. I had a situation where I had a 200 amp main with 225 buss bar. The edison guy to do the disconnect reconnect made me change the wire from 2/0 to 3/0. Is this an ahj situation or a must?
 
Ninmmkmfdm said:
Ok thank you. I had a situation where I had a 200 amp main with 225 buss bar. The edison guy to do the disconnect reconnect made me change the wire from 2/0 to 3/0. Is this an ahj situation or a must?
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The Edison guy was wrong. As Don stated barring a local amendment #2/0 cu is code compliant.

Why is your used name different from the OP?
 
Ninmmkmfdm said:
Ok thank you. And I dont know why its a different name. Thats weird.
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Sometimes people are logged in under one name on mobile and another on some other hardware. There's no prohibition to having more than one user name but it helps us to follow along if the responses come from the same name within the same thread.
 
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