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#90712 - 12/08/04 08:39 AM On-grade wiring method
NFGBillgas Offline
Junior Member
Registered: 12/07/04
Posts: 3
Loc: Buffalo, NY USA
Folks -
I have to install a 1200 foot circuit, 240VAC, with minimal load (5 Amps) to a hilltop location. The terrain is VERY rocky and littered with vegetation. What wiring method can be used laid directly on the earth that is vermin and bear resistant, and that is, of course, Code compliant.
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#90713 - 12/08/04 11:57 AM Re: On-grade wiring method
hbiss Offline
Member
Registered: 12/16/03
Posts: 886
Loc: Hawthorne, NY USA
Nothing that I know of. Such wiring, except for temporary use, is prohibited.

Like it or not, either trench or set poles.

-Hal
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#90714 - 12/08/04 12:33 PM Re: On-grade wiring method
mustangelectric Offline
Member
Registered: 02/08/04
Posts: 494
Loc: Bentonville, AR
Hi,
You can run 4"X4" wood blocks along the ground and support PVC from that. You will need to space the supports so that the conduit does not sag, this means closer than the code calls for...like every 3 or four feet depending on the size...see table 352.30(B). Caddy makes supports for this purpose...they are made from some kind of plastic material. I saw them at a demonstaration they gave. See http://www.erico.com/products/PipePier.asp

This method is used all the time on rooftops and is acceptable above ground as long as it is installed correctly. I know of no article that prohibits running conduit on a pier.

Set the 4X4's down on the ground or stick them in the ground a foot or two. then support the pipe from that.

Have you never seen a pipe on a fence or rooftop or pipe rack?

There is nothing in the code that says a pipe can not be run above ground!...that I know of.. i am sure this will stir up a ruckus! I see pipes all the time run on the ground. Tank farms, oil fields, farms, a lot of places. i would not recommend it for long term use unless you know the conduit is not subject to physical damage! If so your bound to raise it up or bury it. The structure is the key...Install the post vertical or horizontal but they must be on a support and NOT laid on the ground.

You can even use UF cable overhead as long as it is sunlight resistant and supported as required in art 396!

Problem solved!

Hope that helps.

-regards

MUSTANG


[This message has been edited by mustangelectric (edited 12-08-2004).]

[This message has been edited by mustangelectric (edited 12-08-2004).]
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#90715 - 12/08/04 03:32 PM Re: On-grade wiring method
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
I don't know of any thing that requires a Pier although it is common practice of roof tops.

This is just my opinion not having seen the terrain but I would say any pipe installed on grade would be subject to physical damage.

If you use PVC it would have to be schedule 80. Personally I would use RMC and try to hug the ground as much as possible, any place it is 'floating' is a place where it will get stepped on or be a major trip hazard.



[This message has been edited by iwire (edited 12-08-2004).]
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Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#90716 - 12/08/04 03:38 PM Re: On-grade wiring method
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
By the way, that is a long way for 240 volts.

Allowing 5% drop you will need 8 AWG copper or 3% will need 6 AWG copper. (6 or 4 AWG aluminum.)

Bob
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#90717 - 12/08/04 05:02 PM Re: On-grade wiring method
trekkie76 Offline
Member
Registered: 06/19/04
Posts: 220
Loc: baileyville, maine, usa
My company recently ran 2000' of sch 80 up a mountain for a wireless intrenet tower. Ran #2 for voltage drop, State inspector said the table on cover only applied if you covered the pipe. The pipe runs through the woods, not subject to any type of traffic.A lot of running up and down the mountain!!
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