Is it ok to bury power line with water pipe?

madrone · Nov 24, 2008

Newbie question here. Thanks for all the archive info folks!
We're going to be trenching the irrigation pipe for our small farm soon. I wasn't sure if its ok to share some of the trench with the electric. The H2o is 2" poly and the power is 6 gauge in 1" pvc conduit. I'm planning to lay them about 2' deep.
any input would be appreciated.
Thanks

Cass · Nov 25, 2008

Where do you live and what is your frost line?

Sponsor · 2022-01-29T12:20:58-0800

madrone · Nov 25, 2008

Cass said:
Where do you live and what is your frost line?

I'm in Portland, OR and have very little issues with freezing at 2 ft.

Gary Slusser · Nov 25, 2008

I wouldn't use conduit. I'd use regular well pump power cable that is approved to be buried; like millions of wells are installed with.

It may not be to code in some places to bury it with the water line but millions of wells have done it for decades without problems. And if you do, it makes finding the water line someday a lot easier; if you remember they are together.

How or why are you running pump power cable with an irrigation water line? DO you mean you are going to feed an irrigation system between a pump and its pressure switch or tank?

madrone · Nov 25, 2008

Thanks for the input. Here's a bit more info to chew on:
1- The power line I meant is not pump line but power to the well house, thus the conduit. The pump, tank, control box and fuse will be in a well house about 500 ft. from our nearest power source. The irrigation line from the well house runs about 100 ft. the same direction the power is coming from before it veers off. I figured we'd just share the same ditch for that section unless someone suggests otherwise.

Gary Slusser · Nov 25, 2008

Sounds good but I don't see the sense to 500' of conduit but I guess it can't hurt anything but the wallet.

Cass · Nov 26, 2008

You can use UF wire and with a 500' run you may want to do a voltage drop calculation.

How deep is the well?

If the ground is rocky then conduit is a good Idea.

madrone · Nov 26, 2008

The well is now estimated at 220 ft. but thats subject to change. Voltage drop on 6 awg. for the full distance (500+220) is at 2.2% at 15 amps. I'm still contemplating using 8 awg. which drops 3.5.
The power line will be running mostly under our gravel road which doesn't get much heavy equipment but sometimes a log truck or gravel truck. The conduit i'd rather not spend the $ on but it seems a safer bet, especially in this wet climate (not to mention earthquakes).

Gary Slusser · Nov 26, 2008

You really need to go to
www.franklinelectric.com and look up the cable chart for 4" submersibles. IMO you're going about this a bit wrong. It depends on your pump motor hp and the distance. And you should be using regular well pump power cable, it's all rated for direct bury. I would be surprised if you need 6 gauge.

Jar546 · Nov 26, 2008

If you are precise with your voltage drop calculations then I would stick with the #6awg copper. Your pump will appreciate it by giving you a longer lifespan.

Gary Slusser · Nov 26, 2008

I'll bet Franklin doesn't agree with either point, but I'm too lazy to go look up what they call for say 750'-850' for like a 3/4 hp motor. From my feeble memory, my guess is #10 or 8 and that's based on my guess of a 3/4 hp motor for his less than 350' well.

Speedpump could tell us too. I used to know all that data but I haven't used that memory since 2004.

Franklin has made more pump motors and for longer than anyone else, and I'd go with what they say.

madrone · Nov 26, 2008

The Franklin electric site shows a 1hp pump to run 10 amps on max. load. It also says that 8 awg. should work for 990 ft. on the same pump.
When I enter 10 amps on the voltage drop calc. for 240V Single phase, 2 conductors per phase in parallel at 720 ft., I get a 2.3 drop on the 8 awg.
I'd be happy to use the 8 gauge if this is enough for the pump.
One more question to figure this out is about service entrance: Where do I calculate the start in this system? At the transformer, the main fuse box or elsewhere?
Thanks for sticking with me gents.

Is it ok to bury power line with water pipe?

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