ECN Forum
Posted By: Dave55 Parallel Service Conductors - 04/18/05 04:17 PM
I hope you'll excuse my ignorance, but I find parallel conductor sizing for a service confusing. I'm going to be installing a 3PH, 4-wire, 1,000-amp overhead service. I'd appreciate references to the 2002 NEC so I can understand it. I'd also appreciate wire smaller than 500kcmil. I don't recall the pipe size, but it took 2 of us over an hour to install the service heads (500kcmil just doesn't bend well).

Thanks,
Dave
Posted By: Ryan_J Re: Parallel Service Conductors - 04/18/05 04:20 PM
I'm not sure why you would have 500 kcmil, since it is a 380 amp conductor, and according to 240.4(C) it would be either grossly uindersized or grossly oversized.

The code reference to read would be 310.4 and 250.122(F), for starters.
Posted By: Dave55 Re: Parallel Service Conductors - 04/18/05 06:03 PM
Thanks, Ryan.

I'm coming up with (3) 400kcmil, or (4) 250kcmil with a 2/0 EGC. I assume the 75 degree C table is used because of terminations. I don't understand the importance of 240.4(C) in light of 310.4 (...to form a single conductor).

Dave
Posted By: George Little Re: Parallel Service Conductors - 04/18/05 08:19 PM
What type of service is it Delta? Wye? How are you including a GEC? Do you mean the Grounded conductor? Another issue is, Are all your conductors in the same raceway? Could you use a bus bar riser?
Posted By: Dave55 Re: Parallel Service Conductors - 04/18/05 09:03 PM
The EGC (copper) per Table 250.122, but not in the raceway. It's a Delta 3PH. All the conductors would be in the same raceway (4 per RMC, anyway)...and what is a bus bar riser???

Dave
Posted By: George Little Re: Parallel Service Conductors - 04/18/05 09:51 PM
The Grounded Conductor / Neutral run with the Service conductors is sized per 220.22 & 250.24(B)
As to what is a buss bar riser? It is a Service that uses bus bars instead of wires.
Posted By: Steve T Re: Parallel Service Conductors - 04/20/05 03:55 AM
How about 5-3/0's? Then you could use 2" instead of 2-1/2". The utility might not like that though.
© ECN Electrical Forums