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#48268 - 02/07/05 04:59 PM Overhead 400A service  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
What do you guys use for the service drop wires? In PVc

500mcm copper thhn?
600 alum?
And the same question for wiring into the panels, in pvc,
2/0 copper, 3/0 alum
just curious of the costs.


Work Gear for Electricians and the Trades

#48269 - 02/07/05 05:02 PM Re: Overhead 400A service  
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
parallel 250 kcmil alum.


Earl

#48270 - 02/07/05 06:48 PM Re: Overhead 400A service  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Quote
parallel 250 kcmil alum


Boy if those are in the same raceway that is pushing it as much as possible and is only acceptable if the calculated load is less than 368 amps.

250 AL rated 230 amps @ 90 C, four current carrying conductors in a raceway.

230 x 2 x .8 = 368 amps.

240.4(B) allows the next standard breaker however the calculated load must stay below 368 amps.

The last 400 amp overhead I did used one set of 600 Kcmil copper.

In my opinion you are not providing a 400 amp service with 500 kcmil copper (380 amps) or two sets of 250 kcmil aluminum (368 amps).

The service can only be rated as high as the lowest rated component.

Of course take this all for what it's worth, I do commercial work so Table 310.15(B)(6) is out of the question. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#48271 - 02/11/05 03:13 PM Re: Overhead 400A service  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Just bringing this up to the top, I was hoping for some more comments. [Linked Image]

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#48272 - 02/11/05 03:35 PM Re: Overhead 400A service  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,803
Brick, NJ USA
Bob:
OK, it's on top, I'll bite...
500kcmil cu; 4" PVC or RGC dependent on spec's. Occasionally 600 al, but that's a rare bird.

UG is PVC, unless the 1 PE does the spec....
last time I got a change order & spec change in "clouds" when I verified the $$$ of RGC.

Going to the panels....cu, usually 4/0.

John


John


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