PNL BUS/BRKR RATING

[mstrlucky74]

In what situation would a panelboard have different amperage for the MCB and the bus? Most times I see them the same but do remember them being different once in while? Thanks.

 

[packersparky]

In what situation would a panelboard have different amperage for the MCB and the bus? Most times I see them the same but do remember them being different once in while? Thanks.

Some panels have a 200 amp MCB with 225 amp bus. I believe in some cases it is cheaper for a manufacturer to make one bus and use it in multiple panelboards.

 

[Jraef]

Some panels have a 200 amp MCB with 225 amp bus. I believe in some cases it is cheaper for a manufacturer to make one bus and use it in multiple panelboards.

Actually in all cases. Panel bus sizes are only going to be among a few ratings, different from one mfr to another. 60A, then 100 or 125A, 200/225/ 250A, 400A, 600A, 1200A etc. So if you need a 90A main breaker your panel bus is going to be 100A or 125A, depending on the standard product your selected mfr uses. If you need a 300A main, its going to be a 400A bus, etc.

 

[electrofelon]

This comes up in solar a lot. I agree manufacturers use the same bus for different main breakers, but the manufacturer rarely will tell you or document this.
I had some 125 and 250A Siemens factory MLO panelboards and they were exactly the same. I took one of each out of the box and was looking over them and I mixed them up and couldn't tell which was the "125" and which was the "250"

Edit. Just wanted to be clear that you can factory order whatever you want