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Old 08-16-2014, 10:59 AM   #1
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200 amp Sec. Svc. Design Overhead/Underground


Anyone have input on how best to complete this job?:
1) From 200 amp metering panel, I need to go 550 feet to a building site; future custom home, and I want 200 amp service available there.
2) In Northern California, PG&E, and full of government entities scrutinizing every aspect of construction.
3) At 100' from metering panel we have a "protected creek" to cross
4) The existing bridge is not in line with the 550 foot calculation, so crossing via attached conduit to bridge would add @ 150-200 feet to the run

I was thinking of setting three poles from metering service panel to cross the creek, then going direct burial to the future house location. I don't know what the codes are in Sonoma County -- do they allow direct burial secondary service with amperage this high? Is there a UV Resistant and THHN/THWN rated wire, so splicing from pole to underground isn't necessary (a pole chase is all)?
What gauge wire? Aluminum is fine with me!
Alternately, I could quickly trench through the creek bed and avoid the poles, but I don't know if this practice is even done.
Looking for advice

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Old 08-16-2014, 12:12 PM   #2
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200 amp Sec. Svc. Design Overhead/Underground


PG&E web site should have full documentation on all the accepted practices and only your local AHJ can give you the specifics. After all, he is going to have to sign off on it when you're done.

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Old 08-16-2014, 01:08 PM   #3
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200 amp Sec. Svc. Design Overhead/Underground


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Alternately, I could quickly trench through the creek bed and avoid the poles,
If you do that and it is discovered, you will be in trouble. Especially with a protected creek.

You can probably get permission to horizontally drill under it, but that is expensive.
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Old 08-16-2014, 01:22 PM   #4
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200 amp Sec. Svc. Design Overhead/Underground


That's a long distance for secondary. You'll experience voltage drop. Will the transformer be next to your service panel? The utility can be +/- 5% of 120/240. If they're low already you'll be lower.

Not sure about residential equipment, maybe you'll need to factor in a boosting transformer. We've had them before. 2 1/2 and 5% boost I think.

Also, as someone who deals with direct buried services from the 70s. Conduit is always better IMO.

Last edited by clw1963; 08-16-2014 at 01:27 PM.
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Old 08-16-2014, 03:53 PM   #5
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200 amp Sec. Svc. Design Overhead/Underground


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Old 08-16-2014, 04:29 PM   #6
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200 amp Sec. Svc. Design Overhead/Underground


Firstly, I'd set a 400 amp at your metering system. I'd bore it all the way even under the creek in schedule 80. I'd run 500mcm al to be safe.

Good luck, take pics
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Old 08-16-2014, 04:37 PM   #7
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200 amp Sec. Svc. Design Overhead/Underground


Oh, and here is a video on how they do it



Probably around $5000-$7000 where you live including the schedule 80 and wire
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Old 08-16-2014, 06:28 PM   #8
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200 amp Sec. Svc. Design Overhead/Underground


Quote:
Originally Posted by Cletis View Post
Firstly, I'd set a 400 amp at your metering system. I'd bore it all the way even under the creek in schedule 80. I'd run 500mcm al to be safe.

Good luck, take pics
What would the voltage drop be for 500mcm 550' long @ 100amps? (Guessing)

Last edited by clw1963; 08-16-2014 at 06:33 PM.
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Old 08-16-2014, 07:10 PM   #9
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200 amp Sec. Svc. Design Overhead/Underground


1.65% @ 100 amps 240V
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Old 08-16-2014, 07:41 PM   #10
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200 amp Sec. Svc. Design Overhead/Underground


IMO the whole premiss is absurd. By the time you pay for everything for such an installation you would pay less for the power company to run primary and set a transformer at the new location.
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Old 08-16-2014, 08:08 PM   #11
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200 amp Sec. Svc. Design Overhead/Underground


As an example you need seven 550 ft. strands of 4/O gauge aluminum wire to make that run (1100 ft. round trip for 120/240 volts, all 200 amps, slightly over 3% voltage drop). Two for each hot leg, two for neutral, and one for ground.

Whereas a primary circuit (pole transformer and meter at house) would need two strands of (minimum allowing for ice and wind loading) 8 gauge copper, one for hot and one for combined neutral/ground. The worst case is an ancient 2400 volt phase to ground primary circuit supplying 20 amps for which 14 gauge wire in free air would carry the current. A typical modern primary circuit is about 7500 volts phase to ground which needs to supply about 7 amps to give you 200 amps at 240 volts.
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Last edited by AllanJ; 08-16-2014 at 08:25 PM.
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Old 08-16-2014, 09:30 PM   #12
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200 amp Sec. Svc. Design Overhead/Underground


Typical primary wire is #2 ACSR for such an application. You won't dictate it.
Also the PG&E crew will do the work. Lets guess $300 a crew hour x 16 (if they can use a truck to auger and set poles) Material $500 per pole x 3 conservatively. $300 for a 25 kva transformer.

Not including cost of design, wire, guying or riser.

$4800 crew
$1800+ material
$6600
+ overhead

Just an extremely conservative educated guess. If they put entire cost on the requester. They're private so they may.

Last edited by clw1963; 08-16-2014 at 09:36 PM.
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Old 08-17-2014, 07:42 AM   #13
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200 amp Sec. Svc. Design Overhead/Underground


#2 ascr

200 amp Sec. Svc. Design Overhead/Underground-pb250039.jpg


200 amp Sec. Svc. Design Overhead/Underground-pb250040.jpg


200 amp Sec. Svc. Design Overhead/Underground-pb250016.jpg


200 amp Sec. Svc. Design Overhead/Underground-pb250031ps.jpg
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Old 08-17-2014, 08:41 AM   #14
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200 amp Sec. Svc. Design Overhead/Underground


ACSR is overhead. Aluminum cable steel re-enforced.
That's a Cross link poly cable? not familiar with the "tr." Underground. With a concentric neutral I'm guessing. Pad mount transformer.

I've terminated more cable than I care to remember.
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Old 08-17-2014, 09:23 AM   #15
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200 amp Sec. Svc. Design Overhead/Underground


My bad....I should have known that. I think they just called the underground #2 AL on the drawing but ACSR sounded familiar. Yeah concentric...aluminum center and copper outer.

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