I came across a 400 amp service today, it was installed in 1998 and passed inspection.
The service entrance conductors were parallel 250 kcmil alum and landed in a fused disco with 400 amp fuses.
There is 2- 200 amp, mlo panels fed from the load side of the disco, each panel is fed with 250 kcmil alum.
My first thought was why dont these panels have a main breaker in them.
Looking in the code book I see 240.21.B(1) "tap conductors 10 ft long" which seems to say it is ok to protect the conductors this way as long as the oc doesnt exceed 10X ampacity of the tap conductor and meets some other requirements of the same article.
Then I looked at 408.36 which basically says we need oc protection not greater than that of the panel and on the supply side of the panel but there is a few exceptions, of which I dont think any of them apply to this install.
Is this a legal install and if so where might I find the article that tells me it is legal.
Sorry for the long post but wanted to provide enough info for responses.
Thanks
The service entrance conductors were parallel 250 kcmil alum and landed in a fused disco with 400 amp fuses.
There is 2- 200 amp, mlo panels fed from the load side of the disco, each panel is fed with 250 kcmil alum.
My first thought was why dont these panels have a main breaker in them.
Looking in the code book I see 240.21.B(1) "tap conductors 10 ft long" which seems to say it is ok to protect the conductors this way as long as the oc doesnt exceed 10X ampacity of the tap conductor and meets some other requirements of the same article.
Then I looked at 408.36 which basically says we need oc protection not greater than that of the panel and on the supply side of the panel but there is a few exceptions, of which I dont think any of them apply to this install.
Is this a legal install and if so where might I find the article that tells me it is legal.
Sorry for the long post but wanted to provide enough info for responses.
Thanks