25

When turning on high amp appliances like an air compressor or dust fan, the attachment of the ground from the meter box to the water main (pic) sparks occasionally for a second or so. A separate ground from the meter box was also installed a few years ago by an electrician that runs directly to a ground rod outside.

Is this normal discharge, or does it indicate an underlying issue? If it's normal, should I insulate around the ground to avoid a shock?

ground connection

Edit: Ground shows current with certain breakers on. Note: There are two grounds coming from the main box. Only one has current. meter on ground

Update: We're not electrocuted (yet).

POCO came onsite and discovered poorly connected neutral at the city pole byt runnign a load test at the main drop. He reattached it, and the baseline amperage on the ground dropped from 6A to ~.6A immediately. 10x reduction, but still present. Current is now detectable on both the water main and ground rods instead of just the water main.

If I fire up all the power tools, vacuums and heaters at my disposal, I can still measure up to 3A on the ground. This isn't associates with load on any given circuit. It returns to under 1A if I turn off the main and eventually baselines at ~.1 whether or not the breakers are on.

POCO says this is not an issue, but the consensus here and during a 5 min phone call with an electrician says otherwise. Electricians are booked several weeks out unless we pay emergency rates at $770 + 300/hr. Electrician also said all he'd do at this point is repro my circuit by circuit test.

On an editorial note: Thanks to everyone for the suggestions and concern for our safety. DIY has its limits.

17
  • 39
    That is not normal at all.
    – Jon Custer
    Jun 11 at 18:01
  • 6
    When you have sparks with electrical devices/connections it is due to the connection being loose, or bad due to dirt/corrosion. The fix most of the time is to clean the connection and tighten. Problem is you have sparks on a ground connection, which should only have power/electricity when there is a major problem somewhere else in the system.
    – crip659
    Jun 11 at 18:07
  • 6
    Looked at the picture with it zoomed out some. The marks from the sparks look to like they are powerful sparks(like welding). Would get an electrician there yesterday.
    – crip659
    Jun 11 at 18:23
  • 8
    call an electrician right away ... if the electrician tightens the ground connection at the pipe and does not do anything else, then he/she does not know what they are doing
    – jsotola
    Jun 11 at 18:23
  • 9
    OP, once you get this addressed, please update your question, mostly so we find out the exact cause but also so we know you didn't die by electrocution/house fire. Jun 12 at 17:27

2 Answers 2

30

If you see sparks at a ground rod, you have serious problems. Could very well be a lose or weak neutral and a lot of current is returning to the transformer via the ground rod(s) ...the more I think about it, you almost certainly have a very weak neutral or completely open neutral ...very dangerous. Think thru this...grounding conductors are connected to devices, both plug in and hard wired. So if you lose the neutral the frames and appliances are now energized (IE: not at ground potential) Very dangerous, esp. in bathrooms and kitchens. A grounding electrode system is not intended to carry ANY current other than when a defective appliance or device is connected. If you have (or could buy) a digital multi meter with an amp clamp, put it around the wire going to the ground rod and see if there is any current there, it should be very near zero, a small amount of current is OK, but not much, like not more than .1 amps or so. If you have a high current reading, you most likely have an open or weak main neutral.

1
  • Comments are not for extended discussion; this conversation has been moved to chat.
    – BMitch
    Jun 13 at 13:43
50

You lost neutral! This is an outage and an emergency

Your neutral wire no longer connects back to the utility. Out of desperation, neutral is pathing through your neutral-ground equipotential bond, the ground rod and the dirt... to somebody else's ground rod and their N-G bond and neutral. Dirt is a terrible conductor, so this results in crazy voltages.

USUALLY this is the power company's service drop to your house. That is two insulated aluminum wires hung off a bare aluminum carrier wire, which is anchored at both ends. This is both neutral and carrier, and if whips in the wind. Aluminum has no fatigue limit. So the wire snaps!

Often you can walk outside and look at the power company service drop wires and see if the carrier wire appears to be poorly attached or broken. Check both ends.

This wire is the power company's responsibility, and they will repair it fast for free, since it is a legitimate power outage.

What is happening is that without a neutral, nothing keeps 120V at 120V anymore. Now your hot wires are still 240V apart, but your two banks of 120V are drifting all over the place (yet adding up to 240V). This can be hard to detect, but it can also fry your appliances.

If this is at an outbuilding with a subpanel, check your house; if wired old-school (3-wire), then the problem is the subpanel feeder.

You can test this by checking voltages all over the house. A lost neutral is indicated by two groups of near voltages, one group under 120V and the other over by same amount but totaling to 240V-ish (e.g. 105 and 137). If you power up a high-power 120V appliance, this voltage difference changes (e.g. 81 and 160).

Footnote: It is possible that the current on your grounding electrode isn't caused by your own lost neutral, but rather, your neighbor's. However, I doubt that because you switching on large 120V loads has direct effect on the symptom. That wouldn't be so if your neutral was OK.

10
  • 1
    I turned off all the breakers and measured (correctly this time) the ground (updated pic above). As predicted, there is current. The city drop appears intact. No visible separation but difficult to verify. There is a subpanel, but I turned off the breaker for that as well when I checked the ground current. Does this rule out something inside the house? Should I call the city ASAP or wait for an electrician Monday? And thank you!
    – Laramie
    Jun 12 at 2:37
  • 11
    You should not wait. If you have to wait, turn off electricity.
    – vidarlo
    Jun 12 at 14:25
  • 6
    @Laramie Current flowing on ground wire even when all breakers are off could indicate that also neighbor houses have lost neutral, or that there is some load that is not behind the breakers. In any case, I would let the professionals figure the details out, as the situation is very dangerous to go poking around.
    – jpa
    Jun 12 at 17:03
  • 4
    @jpa That's a very good comment. I was thinking: "How the H.E. double hockey sticks could there still be current on ground with all the breakers turned off. But you are saying it's back flowing from other people connected to the same transformer, yikes! The OP's panel was also probably "borrowing" their ground path at times. Very good call jpa, I wouldn't have thought of that . Jun 12 at 20:12
  • 8
    Harper - Reinstate Neutral
    – user253751
    Jun 13 at 9:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.