Why do I have voltage on a plumbing ground strap, and is it dangerous?

Question

We have been having problems with the lights in our basement for awhile now (few weeks), sometimes they will work, other times they just won't turn on.

Today I noticed a thin metal piece in the basement closet and I accidentally broke it off. I am pretty sure it was already breaking/loose because it snapped very easily. It was leading to the water pipe (where the main shutoff is) and just ends there with a metal loop and screw holding it in place. Or at least it was.

Immediately after it started to spark, because it swung and made contact with the piece it broke off of. The lights also started flickering. I managed to get it to stop sparking. But when I went upstairs to get a flashlight, the lights upstairs started flickering and the heat/ac unit had no power. Few mins later the bulbs started going out. I use fluorescents.

I'm freaking out a little bit now, turned off the power to the whole house. I originally was going to try to re-secure the metal tube but its not seeming like that will be enough. I'm hoping to call an electrician in the morning, how dangerous is this problem? Can I try to switch on just the heat and fridge? Plus who knows if I can get someone here tomorrow...

The house is about 30yrs old, with both copper and aluminum wiring.

Update: thanks for all the answers, thankfully was able to get electrician here the next morning, my fiance was mad that there was stuff in that closet. Neither one of us knew that wire was for electricity. He fixed it, it was a grounding wire, apparently also there was corrosion on the outside of the house next to the meter.

So not safe to put anything near the grounding wire now that it's fixed? I wasn't home to ask the electrical myself. If not, I'm surprised there are shelves in the closet..?? It's about 4x2 feet, small shelves about 1x2 on each side, with the pipe and grounding wire in the middle. Alive and well, no fires phew. Furnace transponder blew though, which supposedly will be expensive to fix, circuit didn't blow :(

Answer 1

You're lucky you haven't been hurt!

It sounds from your description like the ground wire came off the pipe clamp

If I was you I would definitely not touch that again. Under normal circumstances that wire should not carry any current. If you are seeing sparks, the ground wire is energized and carrying current.

If it does, it may indicate an extremely dangerous condition. It can shock you (possibly seriously injuring or killing you), start a fire, and damage electrical devices in the house. The shock hazard isn't just with the loose wire, it may be there with incidental contact with the pipes, sinks, etc. in the house. It's not really safe to be in the house.

If it is what it sounds like to me, you pulled the ground wire loose from its lug on the ground clamp - it shouldn't come loose easily, so maybe the wire was damaged, or the screw was not tight. In any case you didn't cause this problem by pulling that wire loose; disconnecting that wire revealed the problem.

If you have problems on multiple circuits in your house, it's especially concerning, you may have a problem with your electrical service (lost neutral or other problem). The problem may also involve your neighbors.

It's good that the main power is off, but that doesn't necessarily make everything safe in the house. I'd call the electric company immediately and consider it an emergency. Call an electrician too, as soon as possible.

edit: The original poster followed up that an electrician came and fixed the issue. With that resolved, incidental contact with the ground wire where it's exposed in the closet isn't dangerous. Disconnecting the ground wire from the pipe shouldn't be dangerous, but it can't be assumed to be safe, because there may be an undiscovered issue waiting to bite you.

Answer 2

Very very dangerous.

That wire could well have been the neutral line of a badly wired "multiwire branch circuit", where two hot wires share a neutral wire. With that center line gone, you can get up to 240 volts on any outlet (double normal).

Or it's a ground wire, but has actual current on it, also a serious problem.

Or it's a bonding wire, also a serious issue if it has current (it could mean your electrical pipes are energized).

Take a motel for the night: far cheaper than having your house burn down. Let us know what happens in the morning, and what the electrician finds. Post photos!

You can also call your electric company: the "lost neutral" problem is something they take seriously, as it can be their fault, and cause fires (see various online videos for examples).

Answer 3

Sounds like your neutral connection to the utility has failed.

Neutral and Ground are bonded together at the service entrance, and at the utility's transformer. Because of this, when your Neutral to the utility is broken, current will find its way back to the utility THROUGH THE EARTH via your grounding system.

Only the utility is permitted to repair the overhead/underground service, so keep your main breaker off until they do that. They should also check the adjacent homes and check for current in the ground.

Once fixed, you can reconnect the grounding strap to the pipe IF the main breaker is off, and IF you carefully measure no voltage or current between it and the pipe.

Put a clamp meter on it and watch when you turn the main breaker back on. There should be no current going through it. If there is, then you need to shut it off, identify the circuit that is leaking current to ground, and fix that.

Answer 4

Update: most comments here seem to come from people that have never seen an old meter. This does not change the factual correctness of the answer.

To make it clear, if you try the below, you could die. You are also committing a crime

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Just adding to the existing answers: replacing the neutral with the ground is a common (albeit possibly fatal) way to steal electricity. Old electricity meters are designed as a motor which slowly turns as current goes through. When neutral goes straight to ground instead of back to the grid, the motor does not turn.

However, most modern (and even not so modern now) meters have automatic protections which disconnect electricity if this happens. This is to prevent both electricity stealing but also the very dangerous accidental coupling of neutral to ground.

If there is no obvious fault that caused this, it might be that previous occupants had some original ideas on how to minimize bills. And you might have to pay for it, should your electricity company blame you for it.

Update: as requested, added a reference. The page does not make it clear that you might need a separate grounding wire that does not go through the meter. http://www.uniquestuff.net/reduce-electricity-bill-with-earth-grounding.html