My 1960 SoCal ranch house was wired without grounds… except for a couple here and there. Apparently I have found the source for most of my grounds right here in my bathroom that I am renovating. You will see below that the heavy ground cable is connected to the cold water pipe. A bare 14 gauge copper wire is run from that connection up to several other circuits, including bathrooms and the furnace:
My question is this:
Can I connect another heavy cable to this and run it to a junction box, then connect the ground wires of several circuits I have already run?
I have put in a bunch of new romex with ground wire. I have not run the new wire all the way back to the main panel, just to the first accessable box – or put in a new box in the attic to run from. I grounded the wires to any of these exposed grounds that I could find.
Rebuilding my home in Cypress, CA
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This quote is from the Michigan 2003 Residential Code: "Interior metal water pipe located more than 5 feet from the entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system." So I'd say what you have and are planning to do would not be a good idea, but I am not an electrician.
Code also says, "The electrode shall be installed such that at least 8 feet of length is in contact with the soil. It shall be driven to a depth of not less than 8 feet." Also, "Electrodes of ... nonferrous rods or their equivalent shall be listed and not less than 1/2 inch in diameter."
Edited 7/31/2006 7:24 pm ET by Danno
There are a couple of things going on here....
Perhaps, at one time, the heavy wire, connected to the water line, was the primary "ground." These days, however, you "bond" the piping, while the electrical service is expected to rely upon a ground rod (or similar item) for a "ground," It's largely a matter of wording.... but behind it lie a few important concepts.
The "ground," as done with the ground rod, is there primarily for lightning protection. Originally, water pipes were considered proper for this use.... but then plastic pipe and Teflon tape came along.... and metal pipes are no longer considered reliable for this purpose.
Still, a metal pipe might become "hot" (electrically speaking, of course :-)). This might happen if, say, someone drops a hair dryer in the sink. Or the water heater gets a bad element. Etc. So, to protect against this, we make sure there is a good path for 'lost' electricity to make it back to the panel.... the better the path, the more likely the breaker will trip.
When a house has it's fuse box replaced, or 'service' changed, it ought to have a ground rod installed, if there is not one there already. You are not allowed, anymore, to rely on the "water bond" alone.
In a similar manner, every circuit needs to have its' ground wire continue all the way back to the panel. It wasn't always this direct; when the ground wire was introduced, for years it was allowed to add ground wires by attaching them to any water pipe. This expedient recognized that it simply wasn't practical to gut an entire house in order to run new wire.
If such exists already, you are generally allowed to leave it be...as long as it does, in fact, eventually connect with the panel. You are not allowed to do this for new circuits, or extensions to existing circuits. For them, you get to run all the way back to the panel.
That's why I'm asking this. I just looked at the panel again, unless there is a rod that is spliced under the panel - though the sill and concrete into the dirt below - then this IS the ground for the house. Seems silly to run back to the box... so that it would end up here anyway.
Gads. I was hoping to NOT have to put in a whole new service panel yet.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
andy posted a real good link to another forum, about three days ago. It was a real good site, go ask there.
"Can I connect another heavy cable to this and run it to a junction box, then connect the ground wires of several circuits I have already run? "
Yes, but not to that clamp.
One of the legal ways to replace unground receptacles with grounded ones is to run a separate ground wire (this is the only place that you are allowed to run a wire not part of a cable or in a raceway (conduit). That ground wire has to go back to a place on the ground electrode system of which the panel ground bus bar is most common. OR connect to another a ground in another circuit (box) that does end up going back to the ground electrode system.
While technically that is only for converting ungrounded receptacles I think that many reasonable inspectors would allow you to do that for other EXISTING circuits.
And that ground wire only need to sized for the biggest breaker that for the circuits that it serves. So probably a #12.
But what is the bigger wire?
If it is the panel ground then you should fix that. After installing a real ground electrode system then you an use the big wire for extending the grounds to those old circuits.
But you need to disconnect from the water pipe and find some acessable box where the connections are made.
It can be behind the vanity, just cut a hole in the back. Or maybe moved to the light fixture box, etc.
Now the other two response don't accurate describe the ground electrode requirements.
Now there are a number of different types of electrodes that are allowed, but for an existing home the most common are water pipe and ground rod.
If you have metalic underground water supply pipes that are at least 10 ft long then it MUST BE USED AS A GROUND ELECTRODE. The connections are made withing 5ft of where it enters the house.
HOWEVER, you are not allowed to use the water pipe as the sole ground electrode. My guess is that they are afraid that it might be replaced with plastic in the future.
So the most commonly available for an existing house is to use a ground rod as a secondardy ground electrode.
However, a single ground rod can be used as the ground electrode unless it is tested an varified less than 25 ohms. That requires sepcial testing.
Thus common practice is to use the water pipe, if available, and a ground rod. Or if the water pipe does not qualify then two ground rods.
In ADDITION, if the water pipe does not qualify as a ground electrode, but is still metalic inside the house (which I see yours is) then it still has to be bonded to the ground electrode system. Again within 5ft of the where it enters the house.
OK, thanks for that info - I'm trying to get my head around it now.
The water feed pipe to my house is PVC, and it becomes copper where it enters the house. This ground connection is on the other side of the house. This ground cable is about 22' long between the copper pipe going into the slab and the neutral bus in the main panel.
So at least one ground rod needs to be added to this system... how about sinking it right there where the current bath drain is - right next to the big cable? I'm thinking my new grounds can either be outside - involving penetrations to the house - or inside where they can be covered with drywall!Rebuilding my home in Cypress, CA
Also a CRX fanatic!