Vertical Bus Rating

[steve66]

I have a 2 section Square D QED switchboard. The first section is a 3000 Amp fixed main breaker. The second section is an Iline distribution section with a 3000 A vertical bus.

The connection diagram shows the 3000A horizontal bus connecting to the middle of the Iline's vertical bus. I thought I read somewhere that the 3000A vertical bus was actually only rated for 1600 amps on the top half, and 1600 amps on the bottom half?

Does that sound right? Do I need to balance my branch loads between the top and bottom half of the vertical bus?

Steve

 

[jim dungar]

I have a 2 section Square D QED switchboard. The first section is a 3000 Amp fixed main breaker. The second section is an Iline distribution section with a 3000 A vertical bus.

The connection diagram shows the 3000A horizontal bus connecting to the middle of the Iline's vertical bus. I thought I read somewhere that the 3000A vertical bus was actually only rated for 1600 amps on the top half, and 1600 amps on the bottom half?

Does that sound right? Do I need to balance my branch loads between the top and bottom half of the vertical bus?

Steve

Kind of.
In reality the vertical bus bar is not split, the left hand side contains the bus run back connection which creates a top and bottom mounting area, the right hand side is continuous.

The I-Line bus stack has limitations on how many breakers can be installed above and below the 'split', on the left hand side. These limitations have to do with the type of the breaker, not necessarily its ampacity.

In any case load balancing is not required.