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05-01-2012, 01:22 PM
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#1
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Member
Join Date: Oct 2007
Location: SC
Posts: 43
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Conduit over solid rock
Job task is to run conduit for a subpanel feeder from the house to the end of a walkway, at the edge of the lake. The first 50' is an easy trench, but the remaining 250' is over mostly solid rock. Plan to use Sch 80 over the rock, but unsure of the best way to attach the conduit to the rock.
Alternative is to attach the conduit to the walkway, but the serpentine nature of the walkway would almost double the length and require upsizing the wire even more.
Ideas and suggestions welcome.
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05-01-2012, 01:39 PM
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#2
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1,000,000th Poster
Join Date: May 2010
Location: Portland
Posts: 9,496
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I imagine pipe mounted on the ground will probably have to take a lot of abuse.
I'd use rigid on mallable standoffs with a couple of expansion couplings.
-John
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05-01-2012, 01:41 PM
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#3
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Senior Member
Join Date: Sep 2007
Location: Phoenix, AZ
Posts: 5,393
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Fill dirt?
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05-01-2012, 01:55 PM
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#4
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Senior Member
Join Date: May 2011
Location: Ohio
Posts: 730
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I say get creative with your conduit bender and do it in metal with concrete anchors
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05-01-2012, 02:00 PM
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#5
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Senile Member
Join Date: Jan 2007
Location: Honolulu
Posts: 7,398
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One glob of wet concrete every____ or so feet placed over the conduit and rock will hold it down ok. A method used often over exposed lava flows.
Bare rock gets hot like roofs do. Depending on the load, you may want to consider de-rating the wire.
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05-01-2012, 02:16 PM
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#6
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Member
Join Date: Oct 2007
Location: SC
Posts: 43
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The area is wooded so not too worried about heat, but not sure how well the concrete would take hold over rock with a few inches of dirt, moss, etc. over it.
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05-01-2012, 02:24 PM
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#7
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Senior Member
Join Date: May 2011
Location: Ohio
Posts: 730
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I like the concrete idea, but you would have to clean the rock down to bare with water for good adhesion, but that would be a good alternative.
When you said schedule 80 - I assumed pvc. Is that correct?
Last edited by acro; 05-01-2012 at 02:44 PM.
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05-01-2012, 02:30 PM
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#8
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Member
Join Date: Oct 2007
Location: SC
Posts: 43
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Quote:
Originally Posted by acro
Well, you would have to clean the rock down to bare with water for good adhesion, but that would be a good alternative.
When you said schedule 80 - I assumed pvc. Is that correct?
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Correct, PVC with expansion couplings.
Kinda like the concrete idea the more I think about it.
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05-01-2012, 02:34 PM
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#9
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Coffee drinking member
Join Date: Sep 2010
Location: IL
Posts: 6,060
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The concrete is a good idea to hold the rigid down. But I would lift the pipe off the rock by about 1/4 - 1/2". It will keep it from rotting away. Drill a 1/4 hole in the rock below we're the concrete will go. Drop a galvanized screw, rod in it to get your hight. This also helps the concrete hold to something and not slide around.
Hydraulic ( water plug ) cement works great.
edit: never mind the rot, I just saw the PVC statement.
__________________
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05-01-2012, 04:04 PM
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#10
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Senior Member
Join Date: Nov 2011
Location: Los Angeles, California
Posts: 228
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Can you go overhead from tree to tree to the last tree THEN down to the ground?
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05-01-2012, 04:17 PM
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#11
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Senior Member
Join Date: Sep 2007
Location: Phoenix, AZ
Posts: 5,393
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Quote:
Originally Posted by Sparkypyro
Can you go overhead from tree to tree to the last tree THEN down to the ground?
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Hillbily style 
Quote:
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Kinda like the concrete idea the more I think about it.
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Shotcrete/Gunite. If the budget is good, cover the whole run and camo paint it.
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05-01-2012, 04:22 PM
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#12
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Junior Member
Join Date: May 2012
Location: BDA
Posts: 2
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ahhhh Sounds like bermuda... if you go with concrete you may want to go with a few more expansion couplings depending on how the seasons are where you are at.
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05-01-2012, 04:45 PM
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#13
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Senior Member
Join Date: Nov 2011
Location: Los Angeles, California
Posts: 228
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Quote:
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Originally Posted by 220/221
Hillbily style
Shotcrete/Gunite. If the budget is good, cover the whole run and camo paint it. |
If its ok for the government to do it in state parks rather then plopping down poles should be ok for a home provided the proper materials are used. I would imagine it would look WAY better and last a lot longer than running it over rock. I have seen this done in my travels all over the country.
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05-01-2012, 04:56 PM
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#14
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Senior Member
Join Date: Jan 2011
Location: canada
Posts: 443
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cant you use armored cable with pvc jacket? In canada we use teck cable a lot for any outside application
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05-01-2012, 05:54 PM
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#15
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1,000,000th Poster
Join Date: May 2010
Location: Portland
Posts: 9,496
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Quote:
Originally Posted by Sparkypyro
If its ok for the government to do it in state parks rather then plopping down poles should be ok for a home provided the proper materials are used....
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Though I think it could be done safely, check out 225.26
-John
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05-01-2012, 05:57 PM
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#16
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Member
Join Date: Oct 2007
Location: SC
Posts: 43
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Quote:
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Originally Posted by Sparkypyro
Can you go overhead from tree to tree to the last tree THEN down to the ground?
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The Tarzan approach? I don't think the good doctor who's signing the check will go for that.
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05-01-2012, 06:10 PM
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#17
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Junior Member
Join Date: Apr 2012
Location: Nebraska
Posts: 24
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Nec 2011 225.26
Vegetation such as trees shall not be used for support of overhead conductor spans
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05-01-2012, 06:10 PM
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#18
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ET Road Warrior
Join Date: Feb 2009
Location: Long Island, N.Y.
Posts: 27,330
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I would use RMC instead of PVC on top of solid rock.. it just gives it more protection when you're between a rock and a hard place..
__________________
There comes a time when people who volunteer their service need to step back and see if it is better for them to retire. A red flag is when they become "cranky" and lose all sense of reality by making decisions that really don't make any sense..
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05-01-2012, 06:14 PM
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#19
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Senior Member
Join Date: Dec 2010
Location: Twin Cities
Posts: 9,914
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Quote:
Originally Posted by B4T
I would use RMC instead of PVC on top of solid rock.. it just gives it more protection when you're between a rock and a hard place..
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I agree. This time.  
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05-01-2012, 06:29 PM
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#20
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ET Road Warrior
Join Date: Feb 2009
Location: Long Island, N.Y.
Posts: 27,330
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Quote:
Originally Posted by Chris1971
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Are you sure..  .. I mean you are making a decision without the help of others.. 
__________________
There comes a time when people who volunteer their service need to step back and see if it is better for them to retire. A red flag is when they become "cranky" and lose all sense of reality by making decisions that really don't make any sense..
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