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so ive got galvanized water lines servicing my house, along with that 6 or 7 wires that are clamped to the pipes,im going to relace everything with pex, im pretty sure i cant just clamp the wires back on the pex, my plan was to install 2 new grounding rods and connect all of grounds to it, any advice please

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    It sounds like too many unneeded grounds. On old houses you might need one ground wire close to where the water comes into the house. Ground rods use one single ground wire from the panel without any splices. Extra ground wires might not be a bad thing, but wondering why so many. Was house upgraded to a grounded(three prong receptacles) system?
    – crip659
    Commented Jan 31 at 22:17
  • I wonder if a bunch of retrofit equipment was grounded back to the pipe. Have you traced them back?
    – KMJ
    Commented Jan 31 at 23:21
  • Might have had a ham radio person in the house. I'd make a new hole for the PEX pipe and cut the iron pipe inside the house after the grounding clamp, leaving the iron pipe outside the house physically in place but not connected to the water supply. It's still functional as a ground electrode.
    – Ecnerwal
    Commented Feb 1 at 0:44

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There are two different types of grounding wires in current use:

  • Ground Rods/Ufer Ground

This is a single wire that goes directly from your main panel to either an Ufer Ground, which is a ground bar embedded in concrete when the building is built (preferred and required in many locations when a new building is built) or to one or two 8 foot long ground rods. If there are two ground rods then they are normally at least 6 feet apart. Only one ground rod is needed if it is tested, but the test is expensive because it requires special equipment. Since ground rods are inexpensive, the usual procedure, unless you have an Ufer ground or possibly a water pipe ground, is to use two ground rods and then no test is needed.

  • Water Pipe Ground

This used to be the standard, since metal (whether galvanized or copper) underground water pipe provides a very effective ground. However, with the increasing use of PEX and PVC plumbing, that is a problem. The big problem is not when you replace all of your metal plumbing with PEX - you know you have to take care of the grounding at that time. The problem is if, as is often the case, the ground wire is attached somewhere in the middle of the house and a section of pipe between that location and where the pipe enters the house is replaced with PEX or PVC pipe and now you have lost the grounding and don't even know it.

That being said, some jurisdictions still require a water pipe ground, but (a) it must be attached as close as possible to where the pipe enters the house (to avoid problems of later pipe replacement breaking the ground path), (b) it is usually in addition to at least one ground rod and (c) it doesn't apply if the supply pipe (from the meter to your house) is plastic.

What you really need to do is check with your local permitting department to find the current rules. In my state (Maryland) as of ~ 2 years ago (when I had a heavy-up) the rules varied by county. Some counties required ground rods only and didn't care about water pipes at all. Some counties required a water pipe ground if appropriate and one ground rod. And my electrician was enough concerned about the possibility of the inspector saying you need a second ground rod, despite having the water pipe ground as required by my county, that he was prepared to install a second ground rod at inspection time if requested.

As far as 6 or 7 wires, that seems a little unusual. Normally it is just one wire, which goes to the main panel. You might have additional wires if there was a previous heavy-up and the previous too-small wire wasn't removed. Or you might have additional wires if TV, phone or other things are grounded to the water pipe. The ideal setup is really to ground everything to the main panel, which is in turn wired (single wire, no splices) to the ground rods and/or entrance water pipe.

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