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#92927 - 04/18/05 09:17 AM Parallel Service Conductors
Dave55 Offline
Member

Registered: 05/08/04
Posts: 666
Loc: Crystal Lake, Illinois, USA
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

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#92928 - 04/18/05 09:20 AM Re: Parallel Service Conductors
Ryan_J Offline
Moderator

Registered: 08/19/03
Posts: 1355
Loc: West Jordan, Utah, USA
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.
_________________________
Ryan Jackson,
Salt Lake City

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#92929 - 04/18/05 11:03 AM Re: Parallel Service Conductors
Dave55 Offline
Member

Registered: 05/08/04
Posts: 666
Loc: Crystal Lake, Illinois, USA
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

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#92930 - 04/18/05 01:19 PM Re: Parallel Service Conductors
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
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?
_________________________
George Little

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#92931 - 04/18/05 02:03 PM Re: Parallel Service Conductors
Dave55 Offline
Member

Registered: 05/08/04
Posts: 666
Loc: Crystal Lake, Illinois, USA
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

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#92932 - 04/18/05 02:51 PM Re: Parallel Service Conductors
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
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.
_________________________
George Little

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#92933 - 04/19/05 08:55 PM Re: Parallel Service Conductors
Steve T Offline
Member

Registered: 02/14/01
Posts: 312
Loc: Oak Park, IL, USA
How about 5-3/0's? Then you could use 2" instead of 2-1/2". The utility might not like that though.

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