During the inspection of a homes electrical system, there are many things that are checked, and too many to mention in this one post, but I just want to address a very common, yet hidden problem with many homes. This only applies to homes with copper supply piping, but the copper piping in it’s self is not the problem. For that matter, when it comes to water supply piping I still think that copper is the best choice but we won’t go into the whole polybutylene debate here.
The point is that if a home has copper piping, there could be an electrical grounding problem. What does the plumbing have to do with the electrical?
When the home is being built, the electrician notices that the plumber is using copper pipe as plumbers have for about 50 years or so and with that, it is used to provide the electrical ground for the electrical panel with the idea that there will more surface in the ground than just driving a ground rod and therefore providing a very good ground for the electrical.
This picture shows the electrical ground clamped to the copper piping at the top of the water heater. In this case, when the house was built, it was providing a good electrical ground, but sometime after the new home owners moved in they installed a whole house water filter.
And here we see that when they installed their whole house water filter, they cut out about 14″ of the copper line just as it entered into the ground and installed polybutylene. From the time that this was done, the house had no electrical ground. Now some will argue that as long as the pipe is full of water, it will conduct electricity and while this is true, where is it conducting it to? The point is that in many cases, the pipe is now plastic out to the street and to the meter.
In some jurisdictions, the water meter is in the garage and not in a box by the curb and when this is the case, there is supposed to be a grounding jumper strap across the meter as the meter should not be depended on for a grounding conductor. By the same token, the water in the pipe should not be depended on as a grounding conductor either.
Now this first case is understandable as the electrical system was grounded at the time of the final inspection, but I am finding many cases where the systems have never been grounded.
This home has the same grounding configuration as above with the ground clamp attached to the incoming copper water pipe on top of the water heater. This is standard protocol for copper plumbing, but as mentioned above, much of the water line coming from the meter at the street is now plastic. In this case, none of the copper piping that was being depended on to provide electrical ground ever came in contact with the ground at all, much less enough surface to provide an adequate ground.
The moral of the story is that it is always better to use a driven grounding rod or some other known metal grounding point like a metal well casing. With the more popular used of plastic pipe, the plumbing system is not a reliable means of electrical grounding.
Now it is good, even with a grounding rod or other electrical ground to have the ground bonded to the plumbing as well as any gas lines. This is for other reasons that we won’t go into here. Because grounding is provided for safety reasons, your electrical could be missing this safety feature.
This is one of a long list of things that a good home inspector checks for and if you have any questions about this or other areas of your home, give us a call and I will personally check this and many other hidden areas that most people are unaware of.
It pains me to say that the first case in this example was inspected by a home inspector about 12 years ago in this condition so make sure your inspector is willing to do more than just a walk through and quick report.
I’ve heard it said that if your inspection isn’t expected to take at least two hours, get another inspector.