There was a time, in the not so distant past, when the only way a house’s electrical system was “grounded” was by connecting the grounding conductor to the metal water pipe coming to the house. There are still a large number of such houses around the country.
While I could talk about where this wire gets connected in relation to where it is supposed to be connected, that could be another whole blog post all by itself.
Today I want to talk about how this particular means of grounding the electrical system, often gets compromised by the installation of plastic components. It is also about how plumbers are not electricians and electricians are not plumbers, so these compromises happen too often. The lowly home inspector is about the only one that is going to draw attention to the problem.
One of the most common ways these older systems get compromised is when the old galvanized pipe from the street is no longer functional (from a plumbing stand point) and gets replaced with a new plastic water line. The installation eliminates the house electrical systems grounding electrode, resulting in the loss of a proper path to ground for dissipation of static charges that might build up on metallic systems in the home.
The ground path is not totally eliminated however. There is also a grounding path back to the ground rod at the utility transformer on the pole at the street–which could be several houses away.
For electrical safety it is important to maintain grounding redundancy.
There could also be ground rods present in addition to the water pipe grounding electrode.
Another way these systems get compromised is when the pipe is repaired with plastic components—resulting in a break in continuity of the grounding conductor.
In the following pictures we can see where the old water line has been abandoned.
And while the new water line from the street is metal, plastic components have been used to connect the new pipe coming to the home to the water pipes inside the home. The grounding conductor attached to the pipe on the house side of the plastic pipe is effectively no longer connected to the incoming water line–to either of the metal pipes. Both would still likely be required to be used as grounding electrodes for the home’s electrical system.
Repairs will not be difficult, but needs to be done to provide proper grounding of the electrical system.
By Charles Buell, Real Estate Inspections in Seattle
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