GROUNDING SUBPANEL

[jcole]

Hi. Need help understanding an AHJ's interpretation. I have 400 amp service on a single family dwelling. Service Entrance Conductors connect to meter base. Meterbase feeds two 200A disconnects all in PVC. Disconnects feed subs. I ran 4/0 aluminum service entrance cable (3 wire w/ ground) from disconnects to subs. I connected main bonding jumper(screw) at each disconnect. Instead of using ground in cable to bond disconnects to subs, I ran a #4 bare copper. I did this because the lugs on disconnects for ground were to small for the ground in cable. I assumed that since the #4 bare was taking the place of the ground in cable, that it would be OK not to terminate and cut off. The AHJ failed inspection because he said the #4 was to small, that it needed to be insulated, and that it had to be ran in same raceway or cable w/ associated conductors. I used 250.122 to size conductor. Is this not right? If not where in code is the right way to size? Also where in code does it say it has to be insulated and in same raceway or cable?

 

[raider1]

300.3(B) requires that all conductors of the same circuit and, where used the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, cable ect...

Also sizing of an equipment grounding conductor, on the load side of a service, shall be done in accordance with 250.122.

Chris

 

[eric stromberg]

If it is a fused disconnect, it would be according to 250.122. But if there are no fuses in the disconnect, wouldn't it be sized as per 250.66?

Eric

 

[tonyi]

In the disco and panels you could split-bolt the SER's alum gnd to a suitably sized copper stub to make it fit the lugs/bars. Splices are allowed.

 

[jcole]

Thanks for the replys. Good Idea Ton. According to 250.122 #4 copper is large enough. Cant figure out why ahj said it was to small. Guess Ill talk to him about it soon.