Panel Feeder

[Alwayslearningelec]

In this example this is all the info I have. It's a new panel. They want the existing feeder feeding the existing panel( to be demolished) to be intercepted and extended to this new panel. Do I need to know existing feeder size? Not sure it matters as I have to splice it.
Don't I need to know the size of the OCPD feeding this panel?
If I size the new feeder( spliced to the existing feeder) for 225A I should be fine?

 

[Dennis Alwon]

It states the Main Circuit Breaker(MCB) is 100

 

[Alwayslearningelec]

It states the Main Circuit Breaker(MCB) is 100

I know. Guess the bus size is irrelevant

 

[retirede]

Your new feeder must either be sized to the source OCPD or obey the tap rules. If the existing feeder is a tap, you can’t “tap a tap.”
If you are creating a tap, you can size it at 100A which is the size of the main breaker in the new panel.

 

[Seven-Delta-FortyOne]

Very rarely, if ever, would you size the feeder for 225A. MCB panels with 200A MCB and 225A rated buss are very common, and often spec’d in commercial work. The feeder would be sized for the OCPD either at the feed, or at the end if utilizing tap rules.

However, your panel schedule is showing a 100A MCB, so a feeder sized for either 100A or above would work.

Your engineer should have provided feeder sizes though. Thats pretty standard. And yes, you’ll need to know what size feeder is existing if they want you to reuse it. This is where job walks and RFIs come in.

 

[Dennis Alwon]

I know. Guess the bus size is irrelevant

It is possible there is a 225 amp conductors feeding the panel.

 

[don_resqcapt19]

It says the feeder is existing, so if you are extending it, you match the existing size. However since conduit and conductor size impacts pricing, you will need to know that for estimating purposes.