Am I going to nee dto move this ground wire?

October 12, 2012 1:45 PM

I have a question about my house's ground wire, and may need recommendations for an electrician in Minneapolis.

I'm having the very, very ugly back steps of my house knocked off and replaced. KICK ASS! But there's a problem: for some damned reason, the house's main breaker box is located right next to the back door, and the ground wire comes down from it along the exterior wall into a PVC pipe that sticks up out of the dirt right next to the steps that are due for demolition (actually, the pipe is kind of embedded in the stucco of the house).

I'm worried that the location of this wire's going to be a problem with the demolition of the existing steps and the pouring of new ones, especially since the contractor wants to widen the steps (and might even be required to because of housing codes; that conversation was a while ago, and I can't remember for sure).

So, my questions: is this likely to be a problem? If it is, is moving the ground wire over a few feet something that I or a sufficiently motivated concrete contractor could do?

If it's a problem but needs to be handled by a professional, I'd love to hear recommendations for an electrician who'd work in south Minneapolis on short notice.

posted by COBRA! to home & garden (9 answers total)

My first thought was "Nah, you can do it" but I googled "Moving a Ground Wire" and I got sone not so good info on how to do it. I also googled, "how to move a ground wire" and was even less enthusiastic about the response.

Call your concrete guy and ask him if he'll do it. If he will cool, if he won't, Mr. Sparky might be the way to go.

FWIW, we don't have a ground wire in our circa 1962 house.
posted by Ruthless Bunny at 1:53 PM on October 12, 2012

We can wholeheartedly recommend Brother's Electric. We had them do a bunch of things at once including running power out to our garage and they were great.
posted by advicepig at 2:08 PM on October 12, 2012 [1 favorite]

Warning: I am not an electrician. I'm a do-it-yourselfer who often bites off more than he can chew, and has a history here on Ask.MeFi of claiming code is way more conservative than it really is. However:

There may be another alternative. In 1942 a guy named Herbert Ufer figured out that burying grounding rods in the alkali environment of concrete made a really effective ground, and thus the Ufer ground was born. So your ground will become more effective if they just pour the new step around it.

Is it code? Well, this page quotes the NEC:

250.68
(A) Accessibility. All mechanical elements used to terminate a grounding electrode conductor or bonding jumper to a grounding electrode shall be accessible.
Exception No. 1: An encased or buried connection to a concrete-encased, driven, or buried grounding electrode shall not be required to be accessible.
...

So your grounding rod is buried, was probably actually driven. Encasing the rest of it in concrete? No worries. If it's not a problem with the demolition, just pour the new step around it.
posted by straw at 2:46 PM on October 12, 2012

Physically, I don't think moving the ground would be difficult: you'd drive a new ground rod (they're surprisingly long, but contractors have hammers), run heavy wire from it to your main breaker box, and connect it (and presumably disconnect the old one; IIRC splices are not allowed in the ground wire). You'd need to check the code for specific requirements on placement and hardware and wire size and such but it's DIYable. (This page has a handy catalog of things not to do.)

Where I live, homeowners are allowed to do electrical work on their own homes, but everyone else doing electrical work needs to be licensed: so if your local laws are similar it might not be quite kosher for a concrete contractor to do it. And your local code might require that a change of that kind be inspected afterwards regardless of who does it.
posted by hattifattener at 3:42 PM on October 12, 2012 [1 favorite]

Consider whether you can use a Ufer ground and if the new pour will have enough mass to use for it. This way it can be incorporated right into the new pour.

Also - agree with hattifattener - LONG Copper ground rod is the trick if you can't use a Ufer.

As long as you fully denergize the panel (turn off the main breaker) the work is safe. However, you might want to borrow or rent a post pounder to drive the rod - it's a pain with a maul or sledge.
posted by BrooksCooper at 3:47 PM on October 12, 2012

Driving a grounding rod can be challenging. First of all, they’re 8 feet long so you’ll need to get up on a ladder to start driving. And if you hit a large rock you’d have to relocate. You might be tempted to cut the rod if you can’t drive it all the way. Aside from the safety issues that might pose, if it’s going to be inspected you should know the rods have two different ends, a chamfered end that leads into the ground and a drive end. The drive end has a listing mark stamped near its end which will be at ground level after it’s driven.

Where I live, in NJ, the rods are often driven just below ground level, but left uncovered for inspection. The inspector will look to see the wire in continuous, no splices, and that it has the appropriate clamp on the rod. They also look to see that listing mark stamp, which tells them the rod is uncut.

I installed one recently at my house and used a hammer drill to drive the rod. Just chucked the end of the rod into the drill and hammered away, worked quite nicely. You’d need a drill with a chuck large enough to accept the rod diameter, which was 5/8 if memory serves, but don’t hold me to that.
posted by PaulBGoode at 11:29 PM on October 12, 2012

Ruthless Bunny writes "FWIW, we don't have a ground wire in our circa 1962 house."

This is fairly unusual in a "ones house completely lacks a ground wire" sense. Likely the ground is provided via a metal water pipe, gas pipe, well casing or fuel oil tank. At any rate it is very much required by code for good reason now so COBRA! don't just disconnect it.

Moving a ground is fairly straight forward though around here a permit would theoretically be required. There isn't anything wrong with paralleling your existing ground with a new install.

Me I wouldn't mess with a ufer especially in an above ground step pour like you've described as there is too much chance of the concrete being broken up at some time in the future and the ground being removed accidentally. Besides a ufer needs to buried below grade to be effective. Code here generally requires at least 600mm below grade.

Much easier is a ground plate installation. Dig a two foot deep hole; level out the bottom; drop your ground plate in after connecting a ground wire to it; fill in the hole. A single ground plate replaces the two ground rods required by Canadian Code. Though maybe the NEC only requires a single rod? And a ground plate is cheaper than a single rod let alone two.

Make sure if you elect to keep your existing ground wire that it is "sleeved" where it exits the concrete if the new pour covers it. IE: you need a short length of usually plastic pipe between the wire and the concrete to provide mechanical protection to the ground wire. Plastic pipe is easy to slit so the length of pipe can be slipped over the wire without disconnecting anything.
posted by Mitheral at 12:15 AM on October 13, 2012 [1 favorite]

On driving new ground rods: I've never heard anyone say "Oh, I don't have enough resistance to ground", so: Standard practice, and I believe current national code, is two ground rods driven at least 6' apart (Code allows for one rod if you can get 25Ω or less, be careful about which time of year you measure this at...).

Looks like the NEC wants ground plates at least 30" deep. I'd go with rods.

Rex Cauldwell's Wiring A House suggests 8 rods, 8' to 20' apart. I haven't seen this much, although I did build my workshop with two ground rods and a Ufer cast into the foundation rebar.

So if you're convinced that you need to move the ground rod you'll probably need a new piece of #4 wire. Rent or buy a driver (I've done two with a sledge hammer: It sucks.). It's a piece of iron tube with handles, capped at one end, that you put over the top of the rod. Dig two holes, at least 6' apart, drive the rods in to within 4" of the bottom of the hole (the driven area provides better contact than the dug area), clamp your wire to your rod using the appropriate clamps (your electrical supply store will sell you the right ones), run it in a trench to the next rod. Put a shield around the wire when it's above ground.

Hidden gotcha: Check on the torquing requirements of the screws which hold the wires. I was shocked by how tight those screws needed to be.

And, yeah, you probably want to talk to either your local building department, or a real electrician, before you do this.
posted by straw at 8:20 AM on October 13, 2012

Thanks, everybody. Looks like it was a false alarm anyway... I talked to the concrete contractor this morning and he said he'd been planning on working with everything as-is, no need to worry about moving anything. So I was freaking out for nothing.
posted by COBRA! at 11:18 AM on October 13, 2012