Electricians: Are copper main water lines still used for the main house ground?
mangler66
| Posted in GBA Pro Help on
I will be running my main water line under the footing very soon, and although I have selected Pexa for the main 550′ run, I still have the option to connect it to a 12′ piece of 1 1/2″ copper pipe to make the through slab section/main ( I am just running a 3″ abs pipe under the footing right now to allow connections at a later time)
My question is, in the age of Pex, are these still useful as a main house ground? Or am i just wasting my money using 12′ of 1 1/2″ copper pipe and a brass pex fitting? For people who do not have any copper in there house, what is normally used for the main electrical ground?
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MaiTai,
I guess the first question is: where are you building? The Canadian Electrical Code provides for a variety of grounding options including water pipes, rods and well casings. The most common method is a copper #4 (or larger) wire encased in the concrete footing. I haven't seen the water main used as a ground for decades, and I can't see much point in switching pipe materials for a short length just so it could be used as a ground.
There are specific requirements, and inspections, for each method. If you decide to go with the wire in the footings, mechanical protection of the ground as it exits the foundation is mandated to make sure it is still intact when construction has finished.
The house is being built in Ontario, Canada.
The question now is whether there is an alternative to the cast footing ground for a slab build, as I may not have time to incorporate this. Will a copper stake pounded into the ground inside the slab before back-filling do the trick?
Hello Mai Tai,
I had the same issue and local code has the panel grounded to a piece of rebar that was passed through the form next to the panel location. It was bent and trimmed after the pour was finished.
Locally it is often called the "UFER" a joke name - because it is often noted during inspection that "you forgot" the ground bar for the panel. (my concrete vendor remembered) I do also have two 8-10' copper rods that act as ground points before the panel due to my meter post being located away from the structure and the main transformer just beyond that.
As Martin notes, local code prevails so it would be the electrician that should know what is done there. I would also echo the observation that it has been many years since I have seen water pipes used as a ground, although old homes may have both pipe grounds and fuse panels. In any case, I just passed the 2" line through the wall with a section of 3" pipe cast in place. I would recommend adding 1-1/2- 2" pass throughs in locations where you might want to pass wire or piping to patios or sheds. My concrete crew used the cross ties as convenient places to put the PVC cutoffs so they wouldn't move far during the pour. And don't forget to block out a hole for the septic as well. It is definitely easier to plug a PVC pass through than drill an 8-10" foundation wall especially since the drill always finds the rebar ;(
MaiTai,
As I noted there are number of alternatives to running it in the footings. Installation of the ground , unlike many other construction tasks, is the exclusive domain of the electrician, and has to be approved prior to burial by a separate inspector. The requirements for each type of ground are quite specific. This is the time to get your electrician involved.
Rolled the dice and installed a Ufer ground, 3 awg bare copper 20 feet long, in the footing 2 inches from the bottom. Took plenty of pics, so I can show any future inspectors. Anyway the NEC calls for resistance less than 25 ohms, and I suspect I will be closer to 5 ohms, so it should be good enough...
Worst thing that is going now is solar installer will give me grief for not doing the same thing in the garage :)
Mai Tai,
As long as the footing is in direct contact with the ground (no foam sub-base) things should be fine.
If you are going to be doing more of the electrical yourself, or just want to keep an eye on who does the work, this is an excellent resource:
https://psknight.com/residential
Actually Roger, a Ufer is named for the engineer who pioneered their use for the US military.
http://www.ecmag.com/section/codes-standards/what-ufer-ground
Patrick,
Thanks for the etymology!
Malcolm,
Thanks for the book recommendation, Just ordered a copy. Now I just have to figure out the safest way to ground the garage sub panel. Looks like a couple ground rods may be the best option.