800A Service

Ok, I know something is wrong, I think it is a violation of tap rules. I got a set of plans for bidding. The service is built as follows. Two 600 KCmil CU feeders from Power company coming underground through a CT cabinet (3 phase) from the CT cabinet up to a wireway which has 2 400A fused disconnects with each set feeding one of these disconnects. one of the 400A disconnects has 2 200A feeds double (two hole) lugged and feeding underground 150' to a MLO panel. The other 400A has three (triple hole lugs) feeding 3 - 150A MLO panels also about 150' underground. (the 150's have 3/0 Aluminum, the 200's have 250 KCmil AL). So the parallel current rating with voltage drop seems sufficient, and concept seems sound... but I seem to think there is a tap rule eing violated. Any comments...

Take a look at 240.21(B)(5). It appears to me that the installation conforms to these provisions.

IMO this installation would be okay, but the problem is the MLO lug panels. 240.21(B)(5)(2) requires each set to terminate at a single overcurrent device that limits the load to the ampacity of the conductors. If the panels were main breaker type I think the installation would fly.

Horst1 said:

Ok, I know something is wrong, I think it is a violation of tap rules. I got a set of plans for bidding. The service is built as follows. Two 600 KCmil CU feeders from Power company coming underground through a CT cabinet (3 phase) from the CT cabinet up to a wireway which has 2 400A fused disconnects with each set feeding one of these disconnects. one of the 400A disconnects has 2 200A feeds double (two hole) lugged and feeding underground 150' to a MLO panel. The other 400A has three (triple hole lugs) feeding 3 - 150A MLO panels also about 150' underground. (the 150's have 3/0 Aluminum, the 200's have 250 KCmil AL). So the parallel current rating with voltage drop seems sufficient, and concept seems sound... but I seem to think there is a tap rule eing violated. Any comments...

Click to expand...

I agree with the others, installation is acceptable. Words highlighted in red - The correct term to replace "feeders" is "service entrance conductors" while this may seem nit picky but is the proper term.:smile: