Long Service run over rocky terrain

Status
Not open for further replies.

JoeNorm

Senior Member
Location
WA
Hello,

I have some friends who are interested in bringing grid power to what is now your classic off-grid cabin in the woods.

The transformer would be located about 300 feet from the house off the main road. The most direct route from there is a straight shot through the woods but over a little bit of soil and bedrock.

To bring in a rock hammer would be cost prohibitive. What are the other options? They could dig down to bedrock, heat bend the pipe to the contours, and lay down concrete. But for 300' that seems pretty crazy. Do people do that for services?

I suppose they could bring someone in overhead? What would be the parameters of this? We are moving away from overhead services around here so i don't even consider it, but maybe its a good application for this.

Any suggestions welcome. Thanks
 

rambojoe

Senior Member
Location
phoenix az
Occupation
Wireman
generator first vote, overhead 2nd. support poles are easy... trenching through glacial erratics is a HUGE job. is the cabin under construction or existing? blm land? how much snow pack in the winter? is it a full time residence? big well pump? and is the ahj the forest service?

p.s.- do they already have propane tanks?
 

JFletcher

Senior Member
Location
Williamsburg, VA
See what the POCO would charge to bring the primary to the house.

This. Also, if the Poco is not going to do this, or provide power from the transformer 300-foot away for free, a solar set up maybe viable.

Also, hang up the idea of heat bending RPVC to the contours of the terrain... The labor to do this on a conduit large enough to contain service conductors is going to be very high, not to mention even if you used factory 22.5* sweeps, you're going to have to install accessible pull points to not exceed 360*.

if this cabin is going to be permanently occupied, rather than something like a hunting lodge, a fossil fuel powered generator will be prohibitively expensive to run.
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
Hello,

I have some friends who are interested in bringing grid power to what is now your classic off-grid cabin in the woods.

The transformer would be located about 300 feet from the house off the main road. The most direct route from there is a straight shot through the woods but over a little bit of soil and bedrock.

To bring in a rock hammer would be cost prohibitive. What are the other options? They could dig down to bedrock, heat bend the pipe to the contours, and lay down concrete. But for 300' that seems pretty crazy. Do people do that for services?

I suppose they could bring someone in overhead? What would be the parameters of this? We are moving away from overhead services around here so i don't even consider it, but maybe its a good application for this.

Any suggestions welcome. Thanks

Where in WA is the cabin? Is the area serviced by a PUD?
Have a cabin near Mossyrock,
Lewis county PUD ran a half mile of rigid for a neighbor who set up a small sawmill, but that assured PUD of steady load.
The PUD does not do overhead in rural areas in timber areas, too many fallen tree outages.
Own cabin just use generator with small microhydro (500W), as there only a few days a year as PUD minimum is 75 cents per day.
Due to forest cover combined with no sun for weeks on end, solar not an option.

Rock: Was part of a study in the late 70s for power to missile silos in Nevada. A D10 cat with ripper makes short work of rock, that was the plan for a distribution network to 4600 silos. Other optin was solar, much of the site area had at most 3 days without sun a year.
 

rambojoe

Senior Member
Location
phoenix az
Occupation
Wireman
This. Also, if the Poco is not going to do this, or provide power from the transformer 300-foot away for free, a solar set up maybe viable.

Also, hang up the idea of heat bending RPVC to the contours of the terrain... The labor to do this on a conduit large enough to contain service conductors is going to be very high, not to mention even if you used factory 22.5* sweeps, you're going to have to install accessible pull points to not exceed 360*.

if this cabin is going to be permanently occupied, rather than something like a hunting lodge, a fossil fuel powered generator will be prohibitively expensive to run.

it doesn't have to run all night... it just seems like a good idea to have backup anyway.. some of these old air-cooled generators can be had cheap, and the off road red diesel isn't too bad. and I agree- crooked underground runs don't pull too well! I don't know, I've seen plumbers lay their pipes on the ground but it sure is ugly. so is over head I suppose but maybe a bit better.
 

JoeNorm

Senior Member
Location
WA
They don't want a generator, they want grid power. I'm sure they already have a small generator. And they have Solar also but its a very small system and they are in the woods.

Can someone expand on the Rigid idea, that seems doable (expensive, yes, but what isn't?). How many feet per pier? Any code references to this method?

Thank you for the suggestions, glad I can abandon the heat bending PVC method
 

Adamjamma

Senior Member
I know you said there is stone there but the big caterpiller tractor used to have a blade attachment they pulled behind it that would just about drag through anything, using the weight of the machine to do it... not cheap but way quicker to hire a cat and a digger to trench it than most other methods and you can get it done...
If they are sure they really want it done, that is...
 

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
Can someone expand on the Rigid idea, that seems doable (expensive, yes, but what isn't?). How many feet per pier? Any code references to this method?

Rigid conduit is described in NEC section 344. Section 344.30 describes the support requirements which are basically one support every 10 feet of straight conduit. The conduit can be at any height above the ground including laying on the ground so the piers can be something like PT 4x4 posts set in the ground every 10 feet or even laid on the ground like railroad ties. If there is only foot traffic, I would keep the pipe near ground level so it can be walked over. If there is vehicle traffic, you will have to either go high enough to drive under or bury a portion to drive over. If going high, you are going to need something more sturdy than just a post, maybe a four footed tower on each side. Hopefully, nobody will use the pipe as a balance beam. It's strong but can still bend/break at the threads if enough force is applied.

You can also use IMC conduit. It's less expensive but more likely to be damaged if abused.

You can camouflage the pipe by painting it green. This may increase the chance of it being damaged if it can't be seen by someone off-roading or the like.
 
Last edited:

Adamjamma

Senior Member
saw that done once in eighties at a farm... near Smith Mountain Lake... in Virginia... short somehow happened on the wires... made a very nice hot fence and caused quite a big bill...

Not saying it would happen to you but...

Have also seen a fence that had its crossrails use steel pipe at one level for electricity, another level for the cable and phone, and bottom level brought in the water... guy actually used the metal as a sleeve for the pvc water pipe... thought it was neat but not sure how good it was actually...
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I vote for above ground rigid. I don't see anyway you can bury this in a cost effective manner and overhead through the tress is just asking for trouble.

I personally would not try to camouflage the conduit, especially if it is along the ground. I want people to see it. I sort of like the fence idea, but don't know how practical it is in that area.

Another option might be to just lay the rigid on the ground and cover it with a mound of dirt.
 

rambojoe

Senior Member
Location
phoenix az
Occupation
Wireman
you cannot attach it to trees. 12 years after i actually did that to some jeffery pines, it makes sense. a 10/20 extension cannot reach the wires! but... for some reason i purchased the porcelian tri-plex supports with huge wood srews on them... and this method is common the further up the mountain you go. of course its 30 miles off the grid... any how- three wires muonted on rated poles 18 feet up look a "heck" of alot better than a 2.5" grc... which is the last g.d. thing i want to see out of the window of my dream cabin... it would all work if you had a good friend with a hammer on a loader hoe...
 
Status
Not open for further replies.
Top