Should I ground this unknown wire to a junction box ground wire?

Question

In the process of cleaning up the basement, I found an unknown wire attached to the a water line in the basement that I can't easily trace.

The waterline isn't copper to the street, though, but uses PEX.

1. Is this an attempt to ground the wire?

2. Is it still grounded, despite the PEX, due to the water in the pipes acting as the electrical current?

3. Should I tie it to a nearby junction box's ground wires instead, or leave it attached to the water line?

Note: this wire is not the circuit breaker box's primary ground wire - that one I can trace, and it properly ties into the water line elsewhere, where it bypasses the PEX.

Answer 1

Is this an attempt to ground the wire?

Maybe historically, but no, the other way around: this should be used to ground the pipe. All metal pipes must be grounded or "bonded". It's important to ground them and make sure they are bonded to the ground of your electrical system and earth (see below)

Is it still grounded, despite the PEX, due to the water in the pipes acting as the electrical current?

The water cannot be relied on to act as a conductor. Whether that section of pipe is grounded depends on where the other end of the grounding wire goes to, or where the pipe goes to. The wire could lead to the panel's grounding.

You should check that and add a picture.

Should I tie it to a nearby junction box's ground wires instead, or leave it attached to the water line?

No, your junction wire's ground will not have the proper gauge leading back to the panel.

However, if it leads to the panel, and there is no other grounding of the panel (by means of a rod or plate) then this could be your old-style grounding. In that case, it should be replaced and upgraded.

and it properly ties into the water line elsewhere

That would be your grounding for that section of pipe.

Best to make sure you can fully trace all your bonding ultimately to a ground rod/plate and to the panel.

Answer 2

Your service panel needs to be bonded to grounding rods.

A water main used to suffice, but not anymore, for obvious reasons.

So it's time for a "health check" on your service panel's Grounding Electrode System. It must go to two ground rods (or one that passed an expensive test).

...And also, your interior metal water pipes must be bonded

to the Grounding Electrode System. That is to keep stray currents from getting on those pipes, and to assure that if an appliance does have a ground fault to those pipes, it flows current, trips the breaker and does not energize your water piping.

Answer 3

It looks like it's a ground bonding wire that bridges past a non-conductive section in the plumbing.

There's no requirement that it be connected to the breaker box ground, but there's no harm in doing that, so long as you do so without cutting it.

Answer 4

This is a common problem when conductive pipes that have been the home grounding electrode are removed and possibly no new method was installed!

That is not an unknown wire but I would bet it is a #6 solid copper wire that goes to your electrical panel.

You really need to install grounding electrodes for your service panel as your current setup would not be safe unless there is 10’ of that copper pipe in contact with earth.

You can splice another piece of #6 to that if an irreversible method like a crimp lug was used (and the crimp needs to be listed for grounding ).

It is possible that copper is longer than needed it could exit the home closer to the main panel providing enough slack to attach to a pair of 8’ grounding rods at least 6’ apart.

You should look into getting this corrected immediately. after this many years of getting bye on a utility ground or just plain lucky it would be a good time to fix it or have it fixed.