When going to bed my client turns on the dining room light, which sometimes instantly causes serious banging of the plumbing in the attic, as well as making the water supply tube behind the refrigerator to jump around, and the toilet fill valve to operate briefly. The last time this happened, she operated another light switch, and this stopped and started the banging of pipes. Any ideas? The house ground appears to be intact, the water heater pipes are electrically bonded, no breakers trip...

A good electrician should be able to find the problem and eliminate it. NEVER SHOULD THE ELECTRICAL SERVICE HAVE ANY EFFECT ON PLUMBING FUNCTIONS. It sounds like there is probably a live electrical path going through the plumbing to earth ground, which is an electrocution or a fire waiting to happen. Do not delay getting this taken care of! Yesterday would not be too soon.

Sometimes electricians will ground on a copper pipe, sounds like it was a hot wire attached by mistake. Like WJ said, get an electrician in there ASAP.

I would investigate a solenoid valve being tied to the line somewhere. It is causing a water hammer affect. Just the application of power to a pipe does not create a force. It must have a device of some form turning on or off to create the water hammer effect. The pipe could be an unwanted conductor to a sol. valve if a control line in near a pipe that is hot or has power that should not be present. It still should cause a breaker to trip if this was the case because the pipe system is a grounded system in your home. Good luck hunting for this problem.

someone used ground as a neutral,shut off brekers one at atime until the problem disapears thats the circuit to check out.Also check your house gronding system for corrosun ,as this system is failing. Danger!

If you had an hot electrical connection to your water pipes; it would pop the breaker. I beleive that you are starting your dishwasher or washing machine when you turn the light on. I don;t believe the light has anything to do with the water pipe banging. It just doesn't make any sense. If you had a faulty ground, it would feed through your pipes, not back through your electical circuit. Your ground and nuetral is hooked up at the main electrical panel only. any other panel (or sub-panel) the ground and neutral are separated. Don't believe the banging has anything to do with the light swicth. If it does, I would sure like to hear about this one.

Max

quote:

Originally posted by Max:
If you had an hot electrical connection to your water pipes; it would pop the breaker. I beleive that you are starting your dishwasher or washing machine when you turn the light on. I don;t believe the light has anything to do with the water pipe banging. It just doesn't make any sense. If you had a faulty ground, it would feed through your pipes, not back through your electical circuit. Your ground and nuetral is hooked up at the main electrical panel only. any other panel (or sub-panel) the ground and neutral are separated. Don't believe the banging has anything to do with the light swicth. If it does, I would sure like to hear about this one.

Max

Max,
It does seem to be involved with the light circuit. When the switches are operated, the banging starts and stops, as does movement of the water supply tube to the fridge. Not just the dining room light, but the kitchen lights, front porch light, and the hallway lights. Trouble is it doesn't happen every time, and only late at night when they're going to bed. Maybe influenced by attic tempurature? Let's say there's more than one thing happening: an intermittant open neutral on the lighting circuit, and the load side of this neutral intermittantly contacting the water pipe? If rats have chewed through the romex at a contact point to the water pipe...I guess I'll have to crawl along the entire pipe run to see, and this in a well-insulated (blown-in fiberglass) attic.

This is not so hard to figure out, I have seen similar problems. You have several neutrals conected to a single return wire. The mass of neutrals in single wire nut have become loose so sometimes the light amperage returns through the pump circuit. The low voltage can only partially run the pump thus the hammer as the pump motor stutters. Find the loose wire nut and fix it before it burns out the pump or causes a fire. Best practice would be to run individual nuetrals instead of combining them. (It is also posible you have a loose screw in the box, this can resolt in the same effect but in my experiance the wire nut is more common)

This message has been edited. Last edited by: L Johnson,

Thanks, but there is no pump...and the only solenoid valves in the house are the clothes washer and dishwasher.

JayS, Still standby my opinion. There is stray voltage acting on something and a loose connection on the nuetral is the most likely cause. Check the connections in the service box and the junction boxes first before you do anything else. Pull on the wires going into wire nuts to see if any are loose. If the amount of wires in a nut is too many break it up.