extended busbars or tap rule

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jgcruz

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California
Easy on me, daily reading your great comments first time question. I have a 400 amp service with a 400 amp main breaker, commercial stand up unit with a distribution panel attached. My question is, can the busbars be extended with 500 mcm conductors to a 150kva transformer without a disconnect next to the tranformer? The tranformer is about 80' away from the service. Is this set up code compliant? if not code sections please. Thanks for your daily input.
 
Re: extended busbars or tap rule

What you are describing is a cable conductor connected to a bus bar.

For reduced ampacity conductor taps, follow the rules in 240.21. These basically limit indoor taps to a maximum of 25' without an OCPD (yes, I know there are some exceptions for High bay installations).

But if your conductors are fully protected by the upstream OCPD then what you have is not really a NEC 240.21 tap but rather a splice where you happen to change the conductor type. Splices do not have a distance limit.
 
Re: extended busbars or tap rule

Jim, Thanks for your help. The electrical inspectors within this county seem to believe its a tap and that tap rules apply. I agree with your opinion. again, thanks for your help
 
Re: extended busbars or tap rule

jgcruz,

This forum has other very respected members with vast knowledge in 'bus extentions',maybe he will respond.
 
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