Grounding wire


  #1  
Old 03-26-04, 09:43 AM
ed'
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Grounding wire

I just replaced some plastic pipe in my house with copper pipe. I was told that I need to ground the pipe. I don't know very much about wiring so I have alot of basic questions. 1) What kind & size wire do I need? 2) Is there a special clamp to attach the wire to the pipe? 3) Do I need to prep the copper pipe before I attach the wire? 4) Does it matter where the the ground wire is attached onto the pipe? Like at the main line coming into the house or before or after the water heater?
 
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Old 03-26-04, 11:14 AM
W
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We are going to need a bit more information to go on here.

When you say 'replaced some plastic pipe in my house with copper pipe.', just _how much_ pipe did you replace. All your interior piping? A few sections? Just the bits exposed under sinks? Is the bulk of the piping system now plastic or copper?

Is the main water pipe going in to your house plastic or metal?

Do you have electric or gas for water heating?

-Jon
 
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Old 03-26-04, 12:31 PM
ed'
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The main water line coming from the water meter is PVC. Somewhere before the supply line entered into the house the pipe transitioned into copper. The copper ran for about 20 feet to the water heater and another 5 feet on the hot water side of the water heater. The polybutylene came in at a tee before the water heater for the cold water and at the end of the 5-foot section for the hot water. So I replaced everything in the attic and down the walls to the shutoff valves under the sink & to the showers. It turned out to be about 250 ft of pipe.

In other words everything in the interior of the house is now copper. The supply line outside the house is still PVC.

My water heater is natural gas.
 
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Old 03-26-04, 12:55 PM
R
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So the pipe entering the house is PVC?

If this is correct, then you must have someother means of grounding your electric service. What is this other means?

Because the pipe entering the house is not copper, but you have copper pipe in the house then you must connect the interior copper pipes to the ground on your electric system. This is called bonding.
 
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Old 03-26-04, 01:26 PM
ed'
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I can't tell if I have PVC running up to the house or I have copper pipe before it reaches the house. It is definitely copper running into the house. I would have to do some digging to find out for sure. But since a plumber at my neighbor’s house bonded his new copper pipes I assume I need to do the same.

So I need to run a bonding wire from my copper pipes to the ground in my electrical box. So back to my original questions. 1) What kind & size wire do I need? 2) Is there a special clamp to attach the wire to the pipe? 3) Do I need to prep the copper pipe before I attach the wire? 4) Does it matter where the bonding wire is attached onto the pipe? Like at the main line coming into the house or before or after the gas water heater?
 
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Old 03-26-04, 05:18 PM
W
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You have a somewhat confusing situation, in that somewhere outside of the house you have PVC, and that your meter is outside the house. Then somewhere outside the house the pipe transitions to copper, and the copper comes into the house. Previously you had some interior plastic piping, but you have replaced that with copper. Did I get that right?

First of all, the original metal piping _should_ have been 'bonded' to the electrical system. Metal water piping is _always_ supposed to be bonded, and if enough of it is in the ground, it is also required as one of the 'grounding electrodes' for the electrical system. You should check to see if your plumbing is _already_ bonded, by looking for a bare copper wire going from your electrical panel to a location near where the pipe entered the house.

Next: size of conductor. The requirements for bonding water pipe depend upon the size of the conductors which provide your electric service. Technically you have to go by the physical size of the wires, but in general for 100A service you need a #8 copper conductor, for 150A service you need a #6 copper conductor, and for 200A service you need a #4 copper conductor. You can also use suitably sized aluminium conductors (they need to be larger), but IMHO you should go with copper. Additionally, #8 copper is small and needs protection from damage; #6 can be fastened directly to the structure, so if you have 100A service, I would recommend you use the larger #6 wire.

Connectors: you need to get special grounding clamps. These are clamps that go around the pipe and get a good grip, and then have a hole with a fastening screw to take the wire. You should be able to get these at any electrical supply. While not required, if you can, get clamps rated for direct burial. When water condenses on the outside of the cold water pipe, you will get some corrosion.

Prep: sand the pipe in the area where you are going to put the clamp, so that you get nice shiny bare metal.

Location: if the water pipes are being used as the grounding electrode (and it is not clear if they should be in your case), then you are _required_ to make the connection within 5 feet of where the pipe enters the house. If you are simply bonding the plumbing, then you can make the connection in an 'accessible' location. Rather than figuring this out, I'd suggest bonding following the 5 foot rule. You should also put a bonding jumper (two clamps with a wire running between) across any dielectric union, or any component which may be removed from the plumbing system. This would mean a bonding jumper across a water meter, and also across the hot water heater.

Good luck!

-Jon
 
 

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