The previous owner of my house (built in 1999) started replacing the copper water lines with PEX. There’s a bonding wire connected to a section of copper pipe that runs from my kitchen sink, but that pipe turns to PEX a few feet down the line, rendering the bond useless. I’m fairly certain the bonding wire runs back to the main panel.

I wanted to finish the job and fully convert over the old copper lines to PEX because I’m dealing with a good amount of copper corrosion from acidic water, which I’ve resolved by installing a pH neutralizer system on the water main. However, I want to replace the copper lines that have already been exposed to the corrosion which is obvious from the green substance on the copper pipes and fittings.

What do I do with this bonding wire?

  • Obviously attaching to the PEX will do nothing.
  • My main panel has the appropriate grounding rods installed so I don’t believe I need to run the wire to another grounding source, but I could be wrong.
  • I’m on a well so the main water supply comes in via plastic pipe so running the wire to the point of entry for the water main wouldn’t make sense.
  • The wire isn’t far from the exterior of the house so I could extend it outside and install another grounding rod but that side of the house is nowhere near the panel and it’s my understanding that even an “additional” grounding rod needs to be installed near the main panel.

I could be misunderstanding the whole situation which is why I’m looking for some guidance.

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  • Is the water main still copper ?
    – Traveler
    Commented Mar 24, 2023 at 3:14
  • No, the bulk of what’s exposed is pex. The main coming off the well is also pex. The line going to the upstairs bathrooms is copper only because they didn’t want to open the walls to replace. Commented Mar 24, 2023 at 11:26
  • Added some formatting to make that easier to read. It appears that you've circled one end of the bonding wire. Where is the other end attached? Also, it seems that the visible attachment point is in the middle of a copper run - where does that copper pipe end?
    – FreeMan
    Commented Mar 24, 2023 at 13:05
  • FYI- everywhere your fiberglass insulation is pushed up is making a cooler spot. The insulation needs to be fully fluffed for maximum R value. When you're done with the plumbing/electrical project, put on some gloves and fluff the stuff down to fill the joist cavities. If necessary, staple some string across the bottom of the joists or use metal insulation supports to keep the insulation in place.
    – FreeMan
    Commented Mar 24, 2023 at 13:07
  • 2
    My understanding is that another reason to bond metal piping to the panel's ground is to trip a breaker in the case of a dangerous electrification of the metal pipes by a malfunctioning appliance, like a washing machine. If you keep substantial copper that connects to one or more appliances it may be wise to bond it to panel ground (grounding electrode system).
    – Armand
    Commented Mar 24, 2023 at 17:18

1 Answer 1


There's no need to do anything with that bonding wire. It obviously serves no purpose with your current setup. Just ignore it, or remove it if its in the way. Or coil the wire up and hang it near the main panel box where it originates, so future owners can use it when they put the copper piping back in when your plastic stuff disintegrates.

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