Best way to dig a 40' long trench to bury wires

[Texas Kingsnake]

Any ideas? How deep do 110 volt wires need to be buried?

[trader_4]

24" in open areas, it can be less if it goes under concrete, etc.

Best way to do it might be a day laborer. You could rent a small walk behind ditch witch type gizom, depending on what's available in your area. HD might rent them. How practical that is depends on the cost and what you have to move it.

[Stormin Mormon]

As directed by the local building code people.

- . Christopher A. Young learn more about Jesus .

. .

[trader_4]

Let me correct that. I just looked at the code to make sure and above is true for direct burial cable. If you use pvc conduit, it's 18". And there is an exception for branch circuits of 20A or less that are GFCI protected, in which case it's 12" regardless if it's direct burial or conduit.

[notbob]

Depends on where you live.

I live in the CO Rockies and we are in the middle of digging up our entire 300 unit snowbird park for a new sewage system. The biggest problem is the rocks. This entire valley is an ancient river bed and one WILL stumble on smooth round river rocks tha size of a Ford Exhibition, six ft or six inches under the surface. We have explosive ordnance experts to deal with the really big boulders.

Bring the biggest backhoe you can afford. We have dozens working, here. Everything from huge Cat's to itty-bitty Bobcat's. It's like a used backhoe lot. Volvo's, Kamatsu's, Deere's, etc. If a bigger backhoe is needed, it's get's trucked in. No one is going out with a pick n' shovel and digging any 10 ft deep trenches anytime, soon. I know.

My first job, after the service, was as a ditch digger. Swimming pool plumbing ditches. Four foot deep in hardpan. At least a pick will break up hardpan. But, the best pick in the world isn't gonna do spit to a 20 ft diameter granite boulder. 8|

nb

[trader_4]

That's true, what I cited is for NEC which is generally followed, probably valid for TX, but locals always have the final say.

[gfretwell]

You can rent a ditch witch trencher. I suppose a lot depends on what the soil is like. Burial depth really depends on where this is. The basic rule is direct burial cable (UF) is 24", PVC conduit is 18" if this is not below a road. There is an exception for 15 and 20 amp 120v on a residential property, that is GFCI protected at the source ... 12 inches. (cable or conduit)

[HerHusband]

The type of soil makes a difference too. We have lots of rocks in our ground, everything from a couple inches across up to several feet across. A ditch witch digger would be worthless here.

We usually start out with a straight line from the source to the destination. Then we alter that route as needed to work around buried boulders. The end result is usually more serpentine than straight line. :)

The first trench we dug for our incoming power line was in the rockiest part of our property. By the time we dug around all the boulders to try and find a way through the various rocks, we had a crater about 8 feet across. Eventually we did find a route through the rocks though. Thankfully, most other trenches we have dug have been less problematic.

I hired a backhoe once to dig a trench for us. He didn't fare much better than we did with shovels. Since then we've just grabbed a shovel and started digging.

Of course, rigid drain pipes or conduit aren't always flexible like electrical cables. If I absolutely can't find a way to reroute the trench around a rock I have resorted to drilling and chipping away at the rock to get the necessary clearance. Thankfully, I've only had to do that once or twice in the last 25 years.

Anthony Watson

[Dean Hoffman]

A call to the Digger's Hotline might be a good first step. There are at least two benefits to using a shovel. Most of us could use the exercise. Plus, a penny saved is a penny earned. A guy might be paying himself good money by not renting a machine to do the work.

[notbob]

Nor entirely practical. My old phone line goes through a PVC pipe. Problem is, water gets into the pipe and when Winter time comes 'round and there goes my landline. I hadda run a above ground line, instead. Sometimes, still gets wet and drops out, but at least I can access it and fix it when it does.

BTW, one the few times WD40 is actaully helpful. ;)

nb

[mike]

Dig no deeper than all the wires/pipes you cross in the path.

[trader_4]

Sounds like the problem there is not using wires rated for wet locations. All PVC underground winds up with some moisture and water in it.

[gfretwell]

The "dig line" (the name is different from place to place) is pretty good at finding buried utilities in the right of way and they usually can find the service from the street to the house but they are not usually going to find wires and pipes on your property that were not installed by the utility. The real reason you call is to avoid being charged if you do hit a utility ... and I see it all the time, even after they mark everything they find.

[gfretwell]

You just used the wrong wire. Anything underground is a wet location, the pipe WILL fill up with water. If you used the "flooded" phone wire, you would have been fine.

[notbob]

All done b4 my time. I was jes dealing with the failure.

nb

[Texas Kingsnake]

Thanks for the info. I have been looking at something called a "ditch witch" for rental but it's expensive and like you said it is not easily transportable. I am also worried what happens if I hit a rock using a rented tool like that. How much could I be stuck for in a repair bill if I wreck the cutter? Can you buy insurance from the rental places just in case? I've never rented a tool in my life so I really don't know what's involved.

TKS

[Sam E]

[snip]

and a shovel is less likely to break a buried gas line.

[Texas Kingsnake]

Thanks for the update. Depth will make a serious difference in how hard it will be to dig the trench. I am thinking I will get the guy who butchered my bricks to dig the ditch for free instead of my suing him. How hard could THAT be not to eff up?

FWIW, I am using underground rated UF-14/2 cable that will be connected to a GFCI to run some new outdoor lights. A juvenile delinquent has moved in next door and I want to put up some motion detector lights and maybe some sort of camera to catch him at work (I looked out the window one day to see him tossing trash in my yard).

I was considering doing the work myself but I have no experience with outside wiring or how to waterproof it so I may just dig the ditches and let a licensed electrician do the hook-ups.

TKS

[Texas Kingsnake]

Oh boy. That might put the kibosh on the digger. Rock'r'Us if you know what I mean.

That means it's not likely I'll be able to use PVC conduit although I didn't have plans to. It sounded like a good idea but I don't see having to rewire it during my lifetime.

I have been considering solar-powered lightning instead of running a cable but I have yet to see the solar powered light that I thought was worth a tinker's damn.

I thought about the backhoe and just hiring an excavation company to do the job. Someone said if I was flexible about when they did it, I could save a lot of money. Not sure if that is true but I guess they might have unplanned down time they'd like to fill by digging a hole for me.

I would hate to have done it once. I had to dig around some pretty big rocks to run my sump pump output. I ended up using a piece of rebar and a sledge hammer to hunt for rocks. Sings out like a carnival attraction when the rod finally meets a boulder. No kewpie dolls for ringing the bell, though.

TKS

[Texas Kingsnake]

I doubt I will run it through conduit. Might make it easier to rewire in the future but that's not a real concern.

TKS