600A feeder

[toomunsch]

I'm installing a new meter socket and CT enclosure outside a building addition, a 600A fused switch inside, and parallel feeder to existing service equipment. I want to use 400 kcmil AL as permitted in 240.4(B), or do I need to use 500?

 

[iwire]

I'm installing a new meter socket and CT enclosure outside a building addition, a 600A fused switch inside, and parallel feeder to existing service equipment. I want to use 400 kcmil AL as permitted in 240.4(B), or do I need to use 500?

You did not say if you where running one or two raceways.

With separate raceways two sets of 400 AL gives you 540 amps of capacity.

As long as you have less than 540 amps of calculated load you could use the 600 amp fuses with the 400 AL

With one conduit two sets of 400 AL gives you 488 amps of capacity.

In this case the maximum allowed overcurrent protection would be 500 amps and of course the calculated load would have to be less than 488 amps.

 

[infinity]

If I'm paying for a 600 amp service I want 600 amps. Bob gave you the code requirements, the guy paying the bill might not be so happy with 540 amps of capacity.