Locating an underground power line

I’ve got an underground power line which runs from the meter on my house over to my shop, maybe 50 yards away. The line is not fused or switched until it enters my shop. (It was installed this way long before I moved here.)

Is there any way to locate the line short of trial and error? Digsafe will only mark the line leading up to the meter.

Well, here we have something called OneCall. You call in and all the services (gas, cable, electric, etc.) will come out and mark their lines for free.

Have you checked for the same in your area? You could probably even call the company directly and ask them to come out and mark their lines. It’s cheaper and less hassle for them to do that instead of install a new line because you severed the current one.

Or…is this not a power company line? Do you have a real property report for your home (we need those here to sell a house, not sure if you need it there)?

ETA: Just saw your comment regarding DigSafe…hm, not really sure what your options are here short of hiring a company to do it for you. Or trial and error.

Hiring an electrician would be cheaper than buying the equipment to find it yourself.

An electrician can either use equipment to directly read the 60hz signal or inject a high frequency signal on to the line and then read it over the ground.

Another option is to have the electric company pull your meter, do whatever work you need to do and then put the meter back when you are done. This won’t identify the location of the line but it will make it safer to dig in the yard if that is your goal. It will also give you (your electrician) a chance to route the shop line through a fused cutoff switch close to the meter.

An electrician that deals in industrial work will most likely have a radiodetection finder for pipes and cables, or you might be able to rent one from an equipment supplier. We use RD7000’sat work, but they are a bit pricey for a one shot deal.

go to where the line enters the ground at each building and draw a straight line. you can carefully dig, with out force, at those locations with small shovel and trowel down to see the horizontal run. pull a string taut between those points. this will give a possible rough idea.

what is your purpose?

is this line spliced in the meter and not after your main breaker/fuse?

if it is spliced at your meter then add an outdoor enclosure with a circuit breaker would be good. have the meter pulled and have installed. or run into and out of house with the breaker inside.

at that distance the shop should have a grounding rod to be the grounding electrode for that building. you don’t have a safe ground without it.

it would be good to know the burial depth and if the cable is protected by a barrier. if it was to the electrical code when it was put in then it would be grandfathered in (OK now even if it was not to current code). the exploratory digging would tell you that.

My goal is to be able to dig some holes for posts for a deck.

The line to the garage is spliced at the meter on the outside of the house with no breaker until the box in the garage. There is a ground rod at the box in the garage.

The house is an old airplane bungalow that was moved to the site. All work–from pouring the foundation to electric wiring–was done personally by the prior owner. He considered himself an electrician. Some of the wiring is good, some is not so good, and some is downright odd. He was fairly old when he did it, and it was all really too much for him. (At the time there was no building inspection in the county in which I live.)

Yes, I think I’m going to pull the meter and then dig carefully where the line should be to see what is there.

Digging to find an underground utility is referred to as digging a “test pit.” I’d make sure the power is shut off before going this route.

Another option is to use a private utility location service like On Target Utility Services, which offers services here in New England. You may have similar companies in your area.

I just found out that Digsafe will also locate private lines for an additional fee.

Thanks to all who responded to my question.

Interesting that the locator service in your area does such a limited job. Requirements for utility location vary wildly by state, and sometimes at the county level.

Here, if I want to do so much as dig a hole to mount a bird feeder in the back yard, the county requires me to mark the proposed excavation site and call for location marking. (It’s free for homeowners.) At their own irregular schedule, the various utilities will then come by and cover the yard in flags and paint marks.

Regardless of where you live, you should be able to hook up with your local locator service either by calling 811, or by visiting http://www.call811.com/state-specific.aspx to find the appropriate service for your area.

johnpost’s suggestion of marking out a straight line between the two known ends of the underground cable and hand-digging at the proposed post locations is an excellent one. The line was probably installed in a straight line between the two buildings, and probably won’t vary more than a couple of feet in either direction. If the line is UF (Underground Feeder) or USE (Underground Service Entrance) cable, it’s just a sturdier version of Romex and it can be penetrated by vigorous digging. PVC or metal conduit will take a lot more abuse, but neither is impenetrable. An engine-powered post hole digger can chew through PVC or UF cable quite easily.

If you need to locate a bunch of holes in the area where you suspect the line is run, it’s probably better to just pay to have someone mark the entire length of the line, and to spot-check all the proposed hole locations to make sure there aren’t any surprises such as telephone lines or gas pipes.

Perhaps a friend with a metal detecter? They find coins, rings and all types of stuff at parks, beaches, etc. A copper, 12 gauge (maybe 10) wire in the ground should be simple.