Grounding wire current

[Ksoko]

Hi all, first, hello moderators. Full disclosure, I am not an electrician, but I do have an electrician working on this. He is willing to put up with my input and asking questions and picking his brain. But I would also just like to get some ideas or see if anybody has had this situation.

I live in a single-family house in a suburb with above ground powerlines and copper plumbing. I have some amps on my grounding cable (from the breaker box), which then go to my copper pipes and out of the house. And then maybe about one amp running throughout the copper pipes (mainly water, but also some gas) of the house.

When I turn off the circuit breaker in the fuse box. The main circuit breaker for the whole house, the amps on the ground wire go down to one full amp. This does fluctuate slightly throughout the day depending on what time or season. When I have a lot of appliances running, big indoor appliances, I can get maybe 7 amps or above on that cable.

The power company just replaced the service line from the pole to my house, so that obviously had a brand new neutral on it, they also tested it, so that one specific element should not be the issue.

Is there any possibility it could still be on the power company side? It just seems overwhelming on my side because no matter which appliance I use on no matter which circuit, it increases the amps on the ground cable. It’s not like it is isolated to one specific circuit. And when this does happen, it does increase the amps that run throughout the house on the various copper pipes.

Like I said, I am not an electrician, but I appreciate the heck out of any kind of person in the electrical field willing to lend some advice or thoughts.

 

[roger]

We will allow this for answers to his question but please refrain from suggestions of how to fix it.

 

[roger]

Ksoko, you might have better luck posting at diychatroom.com.

 

[don_resqcapt19]

Assuming that your area is served by a metal underground water piping system current on the water pipe grounding electrode connection and the pipe itself is normal.

The grounding electrode connections to each of the water pipes serving the houses in the area creates a parallel path for the neutral current. Often the current on the water pipe is 10 to 20% of the current on the service neutral.

However large changes on this current based on the operation of appliances in your house tends to indicate a possible problem with the service neutral. If the utility replaced the overhead, it could be between the meter and your service disconnect. A good electrician should have no trouble in finding the cause.

 

[suemarkp]

This is mostly normal and can't be avoided in a grounded electrical system. The ground rods of your house are in a parallel path to the neutral wire from the pole, because the neutral at the pole is grounded. Your pipes are connected to your ground electrode.

So any neutral current has multiple paths:
1. Along the circuit neutral, to the breaker box, to the service drop neutral, and to the utility transformer neutral.
2. From circuit neutral, to breaker box ground wire, to ground rod, through earth, to utility pole ground rod, to transformer neutral.
3. From circuit neutral, to breaker box ground wire, to CATV ground block, through CATV system to neighbor, to neighbors breaker box, to their utility neutral, to their transformer neutral (which is connected to yours via the bottom wire on the power poles).
4. Same thing as above but for telephone lines.

Having current on the water pipes may not occur unless the water service to your house is metal because that metal pipe in the earth to your house will act like a ground rod. The path is even better if the water to your house and your neighbor's house is metal pipe all the way (no plastic utility piping), as that is the same as running a wire from your breaker box neutral to the neighbor's breaker box neutral.

The gas pipe should be isolated on the utility side of the meter. Usually current doesn't flow on the gas pipes, or if it does it is quite minimal, because the piping in your house shouldn't be carrying much current except between where the water pipes are bonded to the electrical service and where the pipe leaves the house if the pipe is metal in the earth. This is one reason why the ground wire to the water piping is supposed to be within 5' of where the water enters the house if the pipe outside is metal in the earth.

Finally, even with your main circuit breaker turned off, you can measure some currents on your main neutral and grounding system, especially if you have phone or CATV connections to your neighbors. This is a variant of case 2 above. Current from your neighbor leaves from their ground rod, through the earth, to your ground rod, to your neutral, up the utility neutral to your transformer to their transformer.

The amount of current flowing is proportional to the resistance of the path it takes (electricity takes all paths of resistance, not just the path of least resistance). Earth connections are going to have a higher resistance than a pure wired connection, so that is why the current drops a lot when you turn your power off -- the neighbor's current is going through the earth to your ground rod and utility return path. This current will vary based on neighbors voltage drop and how conductive/wet the earth is. Sometimes this can be a problem for people with swimming pools and neighbors with poor neutral wire connections to their utility transformer.