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Old 04-08-2016, 12:02 PM   #1
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Question about grounding wire on copper pipes


I have a suburban home built in the 1980s, plumbed in copper, and I need to replace a shutoff valve near our indoor water meter. I noticed there's a grounding wire connected to the copper pipe above and below the water meter, near where the shutoff valve is. I assume this was installed so any electricity running through the pipe would bypass the water meter.

But does this mean that my house's electrical system is likely grounded to the pipes or does a city water dept automatically put in a grounding bypass when they install meters just to make sure their meter is protected?

The reason I ask is that I'm slowly replacing my copper system with pex when something needs replacing. And when I replace this shutoff valve, I may use pex tubing and a pex quarter turn valve to do this. Of course, pex wouldn't provide a proper ground if my house's electrical system is grounded to the copper pipe, so i wouldn't want to mess up the grounding system.

How can you tell in a finished house if your electrical system uses the plumbing for grounding? Or was this type of grounding only done on much older houses than mine, which was built in the 1980s?
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Old 04-08-2016, 12:43 PM   #2
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Re: Question about grounding wire on copper pipes


Very typical. They use the copper pipe for grounding the house electrical system. Sometimes in older houses you will see that the phone company uses it as well for a ground. See it all the time.

As you replace everything with pex, you will have to ground the house electrical system by using grounding rods. I have seen houses that use the gas piping as a means for grounding, but imo, I don't like that set-up.

Call your local municipality and ask them what local code dictates, or call an electrician and see what would have to be done. Usually, two grounding rods driven 6-8 feet in the ground using proper gauge grounding wire will suffice. Just a suggestion. Check local code for sure.
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Old 04-08-2016, 01:15 PM   #3
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Re: Question about grounding wire on copper pipes


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Very typical. They use the copper pipe for grounding the house electrical system. Sometimes in older houses you will see that the phone company uses it as well for a ground. See it all the time.

As you replace everything with pex, you will have to ground the house electrical system by using grounding rods. I have seen houses that use the gas piping as a means for grounding, but imo, I don't like that set-up.

Call your local municipality and ask them what local code dictates, or call an electrician and see what would have to be done. Usually, two grounding rods driven 6-8 feet in the ground using proper gauge grounding wire will suffice. Just a suggestion. Check local code for sure.
Around here it is(or at least was) code to have ground rods and a bonding wire ran to the water service and clamps on both sides of the meter. From what I understood it goes on both sides so if the meter is removed the water lines are still grounded. For the gas lines it needs to be bonded, I believe this is different then grounded. Most of the time they just run a short wire from the cold water supply to a gas line, usually by the hot water heater if it is gas. This isn't a means of grounding but a means to ground the gas lines from what I understand.
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Old 04-08-2016, 02:08 PM   #4
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Re: Question about grounding wire on copper pipes


Thanks for clearing that up for us ponch.

Yea, i really dont know. Thats why i suggested to call the local municilpality or an eletrician to make sure.
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Old 04-08-2016, 03:59 PM   #5
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Re: Question about grounding wire on copper pipes


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As you replace everything with pex, you will have to ground the house electrical system by using grounding rods. I have seen houses that use the gas piping as a means for grounding, but imo, I don't like that set-up.
For a house built in the 80's he should already have ground rods or other grounding electrodes. However, as long as he has that metallic water pipe entering the house (with an underground length of 10 feet or more) he must continue to use it as a supplemental grounding electrode. The wire to it is a GEC, or a grounding electrode conductor. The GEC connects the electrical system to ground.

The wire over the meter is an EGC or equipment grounding conductor (aka bonding or safety ground). It connects metallic parts of the electrical system and other metallic systems together so that they remain at the same potential as the system ground. You can actually get shocked between two "grounds" of unequal protential.

Any connection to a gas pipe should be a bonding (EGC) connection, not a grounding (GEC) connection.

As far as the piecemeal replacement with pex, as long as an entire branch is replaced with pex you don't have to worry about bonding. If you replace a section of pipe with pex (or other non conductive piping) and you island a bunch of copper on the far side, I would install a bonding jumper over the non conductive section.
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Old 04-08-2016, 04:22 PM   #6
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Re: Question about grounding wire on copper pipes


Thanks oso. Good information.
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Old 04-08-2016, 05:01 PM   #7
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Re: Question about grounding wire on copper pipes


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For a house built in the 80's he should already have ground rods or other grounding electrodes. However, as long as he has that metallic water pipe entering the house (with an underground length of 10 feet or more) he must continue to use it as a supplemental grounding electrode. The wire to it is a GEC, or a grounding electrode conductor. The GEC connects the electrical system to ground.

The wire over the meter is an EGC or equipment grounding conductor (aka bonding or safety ground). It connects metallic parts of the electrical system and other metallic systems together so that they remain at the same potential as the system ground. You can actually get shocked between two "grounds" of unequal protential.

Any connection to a gas pipe should be a bonding (EGC) connection, not a grounding (GEC) connection.

As far as the piecemeal replacement with pex, as long as an entire branch is replaced with pex you don't have to worry about bonding. If you replace a section of pipe with pex (or other non conductive piping) and you island a bunch of copper on the far side, I would install a bonding jumper over the non conductive section.
Thanks for the detailed explanation, and thanks to the others who provided advice as well.

Hmmm, now I'm rethinking using pex in this section to replace the valve. Maybe I'll solder in a new shutoff valve and keep the copper there. How expensive is a jumper wire and clamps if I do go with pex? And for 200 amp service, I can use either #2 aluminum wire or #4 copper, right? How much do you typically save per foot going with aluminum vs. copper?
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Old 04-08-2016, 05:14 PM   #8
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Re: Question about grounding wire on copper pipes


Use 8 ga bare copper wire.
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Old 04-11-2016, 12:35 PM   #9
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Re: Question about grounding wire on copper pipes


Good stuff here...
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Old 04-11-2016, 03:02 PM   #10
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Re: Question about grounding wire on copper pipes


I had the water meter installer come by yesterday (private contractor) and he was pleased to see the permanent ground jumper that I installed across the meter.
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Old 04-12-2016, 12:46 PM   #11
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Re: Question about grounding wire on copper pipes


Quote:
Originally Posted by jmon View Post
Very typical. They use the copper pipe for grounding the house electrical system. Sometimes in older houses you will see that the phone company uses it as well for a ground. See it all the time.

As you replace everything with pex, you will have to ground the house electrical system by using grounding rods. I have seen houses that use the gas piping as a means for grounding, but imo, I don't like that set-up.

Call your local municipality and ask them what local code dictates, or call an electrician and see what would have to be done. Usually, two grounding rods driven 6-8 feet in the ground using proper gauge grounding wire will suffice. Just a suggestion. Check local code for sure.
One metal water pipe (if any) exiting the house and not known to run underground for less than 10 feet must be included as a grounding electrode. The grounding electrode conductor must be attached within 5' of where this pipe exits the house and without the meter, water softener, or other device in between.

When the gas plumbing is properly bonded to the electrical system (grounding electrode system) you cannot help using the gas pipe exiting the house as a means for grounding. But the underground gas pipe does not count as a grounding electrode.

If A is bonded to B then B is bonded to A. But grounding the electrical system to the plumbing in general is not a needed thing to do while bonding the plumbing to the electrical grounding electrode system is.

Two 8' ground rods at least 6 feet apart and connected to the panel ground using #6 copper meet the NEC code for grounding whether or not an underground water pipe is available. If additional ground rods exist and are used for some purpose such as telephone systems, these rods must become a part of the grounding electrode system using #6 copper wire run outside as much as possible along the foundation. However such interconnection may be omitted if it must cross lawns, go under walkways, etc. to get to a shed or other detached building.
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Last edited by AllanJ; 04-12-2016 at 01:06 PM.
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Old 04-12-2016, 04:17 PM   #12
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Re: Question about grounding wire on copper pipes


Quote:
When the gas plumbing is properly bonded to the electrical system (grounding electrode system) you cannot help using the gas pipe exiting the house as a means for grounding. But the underground gas pipe does not count as a grounding electrode.
Underground Gas piping is not counted as an electrode because it may be coated or wrapped in such a way that it is somewhat insulated from good ground contact.

Depending on where you live and your gas supplier, there may be zero grounding contribution thru the bond wire to the gas piping. In my case the gas pipe enters the house from the meter thru the rim joist. The gas supplier restricts the bond wire to the house side of the meter and does not allow jumpers over the gas meter. There is a dielectric union that is installed at least 6 inches above ground on their side of the meter.
They do not want any customer generated ground currents interfering with the cathodic protection on their gas piping.
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Old 04-12-2016, 07:34 PM   #13
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I just want to add some info about bonding gas lines. Metallic gas lines AFTER the meter must be bonded in case of accidental energization. Repeat: this needs to be done on the house lines, AFTER the meter. The reason for this is, the meter and underground utility lines are electrically insulated from the house lines.

Steel gas mains and services (ie the pipes in ground supplying the meter) are cathodically protected with an impressed current to prevent corrosion anywhere the coating is damaged. If the gas utility side becomes electrically connected to the house lines (metal to metal), and therefore to the electrical system's ground by way of the bonding wire, it creates a dead short and nullifies the cathodic protection. This will lead to the underground lines eventually corroding and leaking.

Newer gas distribution systems are made of polyethylene (PE, plastic) with a copper wire for locating, but transition to steel above ground and are still electrically insulted from the house lines. Often, these PE services and mains are connected to older steal mains that are also cathodically protected by an impressed current. The tracer wire to locate the PE services and mains is also connected to the steel mains, so if it made contact with the house lines, it would again lead to a dead short and the potential for corrosion and eventual leaks.

Something as simple as leaning a ladder or bicycle against a gas meter could also cause a dead short of it connect the steel riser to the bonded house lines.

The gas service is NOT a ground, should NEVER be used as an attempted ground, and should NEVER come in metal to metal contact with the house lines.
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