Background: in my neighborhood the water company is renewing the pipe line, taking away the old metal pipes and replacing them with plastic pipes. The electrical network company has thus sent a letter to all the houses (built in the late '60es) advising to check that the grounding was not made by connecting to the water pipes (now this is not allowed, but it was common in the past), as this would basically leave the house with no grounding after the replacement. After this check they ask for a written communication that the grounding is ok, to be done before the replacement works begin.

Is there a way to check how the grounding is made? From the electric cabinet I just see a cable going below the floor, and I cannot wait for them to remove the pipes and then check if I still have grounding.

  • Call electrical contractors/ service companies in your area and have a phone conversation with them. Since this is a wide spread project they will know what you likely have because they may have already checked at your neighbors, they likely also offer free estimates, get several estimates so you know that your being treated fairly. – Tyson May 2 '18 at 12:44
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    @Tyson - I am with you. The only way you can check if you have a legitimate ground is with a megger and you need to be trained on how to use a megger. Probably not a DIY project. – Retired Master Electrician May 2 '18 at 14:48

Your house will be grounded either by the metal water pipes as you said, by a ground rod, or rebar in your foundation (if it has it).

The most common modern method is the ground rod. Normally if a ground rod is used, it would be placed on the outside of your house on the other side of the wall your electrical panel is. Because you state that it goes below the floor, it's not likely you have a ground rod (at least not one you can see outside). You can easily check for an exterior ground rod by looking outside next to the foundation on the other side of the wall of the electrical panel. You should see a copper wire going into the ground, and possibly the ground rod itself sticking up a little bit.

You stated that your house is older, so I'm not confident that your house is grounded by any rebar in the foundation as your house probably doesn't have it. If it's grounded to the rebar, you may not be able to observe the ground connection without digging if the foundation was poured over it.

If the panel is grounded to the water pipes, and the ground wire can be seen going into the floor, I'm assuming the side of your house the water comes into is on the same side of your house that the electrical panel is on. I say this because you want to ground the water pipe as close to the entrance of your house as possible. This is so that if, for example, you replace your water lines in the house in the future. If you take off the water pipe that the ground wire is connected to, you will have an ungrounded house. By having it near the entrance, you are that much less likely to accidentally disconnect your ground. I would have thought that they would want the water line to come through the wall of your foundation, rather than the floor, but it's possible.

So how do you determine if your house is grounded with the water pipes? You can do it by observation as described above, but this won't help if you can't see where the ground goes as you can with a ground rod. Some might say to disconnect the ground conductor from the panel and measure the impedance between the ground wire and your pipes. This won't work because the ground path could be going through rebar, a ground rod, or some other method before reaching the pipes.

Unfortunately unless you dig through your floor, you can't tell where it connects. You would need specialized meters that would test ground impedance, but even this method isn't guaranteed to pinpoint the ground connection. An electrician should have this meter though. If I was in your position, I would call my utility company (water and electric) and ask how you should determine the ground connection. Explain that your ground connection isn't visible and that it would be an expense to determine the ground location. Hopefully they will reimburse you in some way, but normally the utility's responsibility ends when it enters your house.

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  • Ufers do not work that way. Seems heavy on guesswork and unsupported opinion, and very lengthy and wandering. – Harper - Reinstate Monica May 4 '18 at 16:27

Go to your service panel ( main panel if you have two). There will be a bare wire exiting the panel alone. Sometimes this wire will be bold green, sometimes green/yellow stripes. You won't confuse it with anything else.

Follow that guy. It will lead one of several places:

  • to a water pipe
  • to a bit of re'rod sticking out of your concrete foundation ( this is an Ufer ground)
  • through the wall, outside the house and to one or more copper plated rods driven into the earth. (These are ground rods).

Ufer can't be retrofit. So if it's a water pipe, convert to ground rods. Driving two is cheaper than qualifying to use only one.

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  • I explained this in my answer, but in much greater detail. What was your reasoning to create another answer? Did you not read what the current answers were? – EEKeefe May 2 '18 at 13:21
  • @eekeefe TLDR... – Harper - Reinstate Monica May 2 '18 at 13:59

Turn off power The cable you see going below the floor is the one .it should be yellow or striped yellow.trace it and when you read the ground and the cable disappears.dig around that area and there should be grounding rod down .see if it is connected to water

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  • Why turn off the power? Lots of people don't know how to do this and may turn it back on too soon after shutting it off. They may stumble and trip without lights on. – Jim Stewart May 2 '18 at 10:32
  • Hello, and welcome to Stack Exchange. It's hard to know what you're trying to say; you may want to spend a little time editing it to make it clearer. – Daniel Griscom May 2 '18 at 11:29
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    US households use bare copper conductors for their grounding conductors. I assume that the house in the question is in the US. – EEKeefe May 2 '18 at 12:39

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