800A Service

[Horst1]

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...

 

[augie47]

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

 

[mistermudd]

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.

 

[barbeer]

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...

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: