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grounding copper pipe question

Posted by reed50 (My Page) on
Thu, Jul 22, 10 at 17:04

We had the grey plastic pipes replaced in our manufactured home with copper pipes about 5 years ago (still plastic coming to house). I'm now finding out that the copper pipes should have been grounded or bonded, and I'm pretty sure they were not. Is this something I need to have done and can someone explain why? Thanks for your help


Follow-Up Postings:

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RE: grounding copper pipe question

Yes, you should bond the metal water pipes to the service. Electrically conductive materials, such as copper water lines, that are likely to become energized are bonded to provide a low impedance path for clearing ground faults that otherwise would energize the materials at a level above earth potential. Metal water lines are considered as likely to become energized.


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RE: grounding copper pipe question

Question (please be patient with a female who's trying to learn): how do my water pipes become energized?


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RE: grounding copper pipe question

Water pipes can become energized when they come into contact with anything in your electrical system or any appliance etc. Just think of all the appliances that are either connect to or right next to water - dish washer, garbage disposal, water heater, washing machine etc. Also, it is pretty common for electrical wires and pipes to run along similar paths.

Of course, if everything is installed properly and working properly, water and electricity don't come into contact with each other. The grounding is only there "just in case." Eventually though, everything breaks. Grounding everything helps insure that even if something goes wrong, it won't injure you etc.


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RE: grounding copper pipe question

okay, I'm starting to kind of understand. Another question: if my appliances like dishwasher, water heater and washing machine themselves are grounded, does this not protect things? And, is one of the concerns about the possibility of a live wire touching one of the copper pipes? Thanks again, and sorry for what I'm sure are stupid questions. You guys are really helping me.


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RE: grounding copper pipe question

I would check and see what kind of fitting was placed at the wire entry and exit points of the copper tube. If there is no protection the copper tube could cut into the wires. Also current flowing through a wire can induce a voltage into the copper pipe.
Put a ground rod into the ground and clamp a #8 wire to the rod and the copper tube.


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RE: grounding copper pipe question

The short answer to your question is no.

The connection to the metal water lines is based on the worst case scenario and the size of the conductor between the service panel and the water line is based on the size of the conductors that make up your service entrance. Generally speaking, for a dwelling, this bonding conductor would be #4 copper for a 200 amp service and #6 copper for a 100 amp service (#8 is permitted for a 100 amp service, but would have to be armored or have some other type of physical protection). These sizes have considerably more capacity than the equipment ground that runs with the circuit feeding your appliances.


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RE: grounding copper pipe question

I think the OP's post may have been misunderstood somewhat. This is a manufactured home and the grey plastic water pipes are polybutylene, which have had a problem with breakage at the fittings. New manufactured home now use PEX. For repairs of the older polybutylene, copper is often used to just get away from the whole problem. So now it appears the OP has had the entire plumbing replaced with copper, but it is still fed by a underground PVC supply at the entry point to the home... much like a stick-built home on a well.

I don't know the answer to this question regarding "code" on a manufactured home, but it seems like bonding the copper after the transition from PVC would just be a good idea. One bond at that point covers all the updated plumbing. Of course bonding needs to carried across such things as plastic water filters, softeners, etc.


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