Was working on a old apartment complex, it has 6 meters, and six panels, five for the apartments numbered 1-5 and one panel for the house, common circuits. I was working in apartment no.2 and was replacing countertop existing 3-wire receptacles with GFCIs, since no one is in apt. no.2 and is my wont to do I pulled the main fuse block for apt. no.2 checked the the fuses to ensure that the circuits were dead and they were. Back at apt, no.2 I started to remove the countertop receptacles got two of them pulled out and started to remove the wires, imagine my surprise when I received a shock I checked the voltage at the wireing and H-N there were 0 volts check the voltage H-G and read 66.5 volts. Upon further inspection I discovered a single black wire attached to the green grounding screw and exiting through the back of the box and attached to a nearby waterpipe. The service has one ground-rod and all the panels are tied together with no.4 copper. The interior water lines are all copper but there is no bonding to the service for this water line. All of the old 2-wire cable has a similar black wire piggy-backed to it and run to different sections of this, in house ,water line, and even some of the piggy-backs are run back to the panels but not back to all of them. Water to the apartment is from a well and the underground supply is plastic. Has anyone seen such a mess as this before ??? Thanks -Mark-
If you get into the 2002 NEC for services and equipment grounding of such, you can see it addresses such problems with the correct methods of grounding, thus eliminating the small current path that you experienced. Yet, as when some folks are in the state of mind that "Hey some ground is better than a correct ground", some poor homeowner may get the experience of a lifetime.
Not an electrician (hey, stop that razzing, now) and don't do any wiring but have really learned a great deal here. I just keep quiet and learn. I just like to know what's going on in the other trades around me. Can someone give me a short, layman's explanation of what was going on here? Why 66.5 volts through a waterline? Partial ground/bond? I always like to be able to speak in a halfway knowledgable fashion to other tradesmen, so...? By the way, I found you guys via the safety portion of the site which is excellent.
Sparky: First thanks for responding, When I first got zapped I went back out to the panels to make sure that everything was really off, it was. So since I was replacing the existing 3-wire receptacle with gfci s when I cut the ground off the receptacle the voltage disappeared from the hot to ground, also removed the grounding wire from the water pipe in the kitchen. This is a 5 apartment complex with a compost of items old panels add on meter bases shodding grounding, surely if I were an inspector I would shut the place down until they upgraded the system. The panels are located above the laundry area so if you need to access any panel the washer and dryer have to be removed, etc. In these old panels and there are five old ones one Sq.D for the house panel, they are overstuffed. The lugs used for the Grounding conductor(which is No.4 copper) has two of them a feed-through, and a couple extra cables used as grounding paths for individual circuits, from these two lugs a bar runs to the bottom of the panel to the neutral bus and it has 4 screws and of course there are a couple of extral whites there, the whold system is an acccident waiting to happen, and just seems to be a generator of ground currents. I informed the owner and he said he was told to do that by his cousin, Who was an electrician, so they have these 'Piggy-backed'grounds everywhere, and this was done so that the owner could install the 3-wire without having to add any gfci s. The scary part is after I told the owner that I was shocked off the grounding conductor, he admitted that he had to on more than one occasion, and thought it was pretty funny. This kind of condition I think is serious and he refuses to do anyting about it. When the apartment is fully rented there can be as many as 20 people there at anyone time, I would think that the voltage rises and falls with usage. I have recommended that it be fixed immediately but havent gotten any response from the owner.
Thanks again for the response -Mark-
Re: Spurious water-line#8416 03/26/0208:53 AM03/26/0208:53 AM
Bill: Thanks for the reply. No not yet, because the owner only wanted limited repairs, and has to authorise all the work. The scary thing is even he has been shocked off the water pipe and doesnt think it warrants this much attention. Is there a possibility of an open neutral in one of those meter sockets ? I guess I am trying to get all the 'ammo' together before I go back to him to further check the situation.
My guess is that all this additional grounding has caused a kind of cool return path from all the various units to whoever is the bestest, shortest path to good old TERRA FIRMA. You would literally have to seek out all the spare taps of GRDS & NEUTS to see who is not where they should be. The bonding is quite overkill and causing the big dilema. The sorta estimate would even shock the typical JOE! Could always have the owner help with T&M, they follow and get to be a tester, hey hold these two things for a second.