I recieved a call from a potential seller of a single family home saying the buyer's inspector measured 4 amps on the water service. Our village does not do single family home sale inspections. The problem could be a loose neutral anywhere on the block. Our plumbing code does not allow plastic water lines. Anyone have a solution for this?
The way I understand it is that if every house has copper lines between them, and every service is bonded to the lines, then the parellel path cannot be avoided... In fact, good workmanship with strong continuity on the water lines will actually allow more current to flow... They will divide the current between them in inverse proportion to their resistances, so a good connection on the water lines is going hand in hand with the poor connection on the neutral, and a bad neutral isn't always the case either... What's the resistance of 3/4" Copper Pipe per 100 foot or so? How can one relate this resistance to divide the load?
(Psst: Pauluk or Scott35 listening here?)
I figure if ya got current on your grounding electrode conductors, it could be 'cause ya got a really good ground. So, is it a bad thing?
-Virgil Residential/Commercial Inspector 5 Star Inspections Member IAEI
Re: Amps on the water line#11492 07/15/0206:15 AM07/15/0206:15 AM
Let me tell you a little story that may, or may not shed some light on what could be the problem. A few years ago, an instructor told me of a "strange" situation, and how they solved it. The complaint was that the home owner and his family kept getting shocked by the plumbing system in the house. What really added to the problem was that it would "come and go". One day everything was fine. Then, for some strange reason, someone would get shocked on the kitchen sink, a shower head, etc. This instructor of mine went to investigate, and this is what he found. The plumbing system became hot only when the dishwasher was on. So, they pulled the dishwasher out, and had a look. Whoever installed the dishwasher did not connect the EGC. In fact, he said, that they had cut it off at the outer sheath of the NM cable. On top of that, they ran the NM cable under the frame of the dishwasher (between the floor and the frame). As a result, over time, the dishwasher rubbed a hole in the insulation. When the dishwasher went into the rinse cycle, it would shake alittle, and the frame would come to rest on the hot conductor. Now, here is the other twist. There was no bond between the plumbing system, and the neutral at the service. So, what was the result? No path back to the service for the ground fault. With copper lines connecting all the plumbing equipment, you've got a "hot" plumbing system. Steve, Sparky and WV66 know a lot more about residential applications than I do. So, I would consider what they have to say, and while you are out there on site take a look at all the equipment that is connected to the plumbing system, and check for a fault with no return path to the service. Also, check the bond between the plumbing system, and the neutral at the service. If it doesn't exist, bond it, and see if it helps. That bond could cause breaker(s) to trip. If it does, then you will know which equipment is the problem. I have heard of people doing what Sparky is suggesting, but I've never had the "pleasure" of doing it myself. At least consider what I have to say, and if it works for you, then, more power to you. If it doesn't work........hey, I tried.
Smoke on the water line, Fire in the sky, Doc
The Watt Doctor Altura Cogen Channelview, TX
Re: Amps on the water line#11496 07/15/0211:02 AM07/15/0211:02 AM
Sparky, is correct. There will always be current on the metal under ground water piping system in a code compliant installation if the water piping system is common to other buildings connected to the same utility transformer. In some cases, this path via the water piping system may even be a better path than the service neutral. Also remember that the current you are measuring on the water pipe may very well originate in a different building. This current exists even when there are no problems with the service grounded conductor. It will, of course, increase if there is a problem with the service neutral.
Re: Amps on the water line#11497 07/15/0202:55 PM07/15/0202:55 PM
Yep, if all the water lines are metallic throughout and with multiple grounds at the xfmr and each house, there's bound to be some current flowing on the pipes. How much will depend upon the relative resistances.
We have a similar situation in the U.K. with our PME distrubution system, which is basically the same as the standard U.S. arrangement as far as grouding goes.
In fact the very presence of currents on the pipework with this system resulted in our "code" ruling that a different grounding arrangement must be used in the supplies to gas stations and other similar plants.
Re: Amps on the water line#11498 07/15/0207:16 PM07/15/0207:16 PM
250.68(B) Effective Grounding Path. The connection of a grounding electrode conductor or bonding jumper to a grounding electrode shall be made in a manner that will ensure a permanent and effective grounding path.
Where necessary to ensure the grounding path for a metal piping system used as a grounding electrode, effective bonding shall be provided around insulated joints and around any equipment likely to be disconnected for repairs or replacement.
Bonding conductors shall be of sufficient length [not like a banjo string] to permit removal of such equipment while retaining the integrity of the bond.
Reason: To protect the water service technician when they are removing the water meter, otherwise they are sure to get a shock!!