Electrolysis in Copper Pipe – Plumbing Question 369

Question:

I am having serious electrolisis problems in the copper lines in our home. I want to replace the copper with pex, but am afraid that the problem will persist in the metal fittings used with pex. Will they be OK?

Answer:

The cause of electrolysis is often hard to find; in homes where the cold water pipe is the grounding source for the electrical panel, plumbers have often suspected that a problem somewhere in the neutral line could cause stray current that is then conducted along the pipes. If it is electrolysis, then providing a break in continuity through the use of a dielectric union should prevent electrolysis downstream of the union. Likewise, using PEX would eliminate the path for the stray current to follow, as PEX is not electrically conductive.

But there’s more here than meets the eye. If your cold water pipes are used as the grounding source at other points, you could create a potentially dangerous situation.  And because even low transient voltage can still be dangerous, it would be best to have an electrician test the pipes for either DC or AC current and find the cause. It could be as simple as a loose neutral wire at an outlet.

Also be aware that there may be transient voltages in the earth unrelated to any problem with your home’s electrical system. This is rare, but can happen. If this is the case in your area, then any metallic fittings in contact with the earth would be susceptible.

Finally, electrolysis is different from galvanic corrosion. Galvanic corrosion is caused by dissimilar metals touching, such as copper and galvanized pipe. In some cases, under slab leaks have been attributed to construction debris, such as nails or stucco wire, being in contact with the pipe in the earth.