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| Subject - bonding cold water pipes | |
| ikayla |
Could someone please explain the bonding method for a cold water pipe when you have a plactic water line entering the residence. Do you have to bond before the first link? |
| Scott Vickrey | You'll have to bond the interior metal water piping sytem somewhere. It has to be accessible too. In a crawl space would be a good place to look. Here's some more info: http://www.ul.com/regulators/ode/0203.pdf |
| lectricb | If the incoming water line is PVC it will not provide a reliable ground reference. In most cases an additional ground rod must be driven. The purpose of bonding the cold water pipe is to give the electrical distirbution system a ground reference. |
| ricky | Article 250-80 covers metal piping. |
| JimmyDee | It is a good idea to bond all the metal piping and duct work in the house so they all have the same electrical reference. (ground). If the pipe coming in is plastic, 2 ground rods 6' apart must be installed for the grounding electrode. When I do a house I bond the water system, hot and cold, gas line, duct work and street and house side of the water meter. Some time when I have more time I will tell a story of the house that became hot (Alum siding) because the gas line, due to an accident, became hot. The poor dog almost died and the kids got shocked on the storm door. Jim |
| Electricman | When all ot the interior water system is in cvpvc the AHJ that ususally inspects my work insist upon a second ground rod placed 6 ft away from each other(I always use 2 ).When copper piping is used I bond on supply ahead of the meter or at the well tank whichever is used. I also use a bonding jumper at the water heater to bond both hot and cold lines together and also a jumper to the gas system if one existist. Other bonding that is a concern is at a whirlpool tub the motor must be bonded to the water piping system if it is copper. |
| Electricman | And dont forget to jump the water meter. |
| David Hyatt | I thought it was illegal to bond to a gas line? 250.52(7) Also I thought the whole purpose of grounding to a water pipe was for a supplemental ground, if the incoming line is PVC whats the use? Normally I will go to the ground rod from the meter and to the water pipe from main panel is it is metal. I see why you would bond water pipes so they will be grounded incase of electrical charge but this would not be considerd part of the grounding electrode system unless it is metal coming in and with in 5 foot of entry with some exceptions. |
| Electricman | David I dont have my 2002 code book on hand but I believe its 250.104 that you want to look at. I dont think bonding is for supplemental ground (thats the reason for additional ground rods) bonding is to ensure a safe path for current in case of a fault.I had an instructor tell me once that electricians often confuse bonding and grounding. |
| David Hyatt | Yea, that is what I was just reading. I was confusing bonding and grounding. Thanks I see where bonding gas lines and other metal piping have to be bonded, but never seen it enforced in residential,Why? FPN 250.104(4)b says metal air ducts to be bonded also. Are these already bonded with the equipment groung. Like I say I never do these things but I should start. Never was even taught to and never was called on it in an inspection.
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| Electricman | I dont bond the duct work (I guess I should ) but I have seen some careless hvac guys short a wire out on it without it being bonded so I would think its actually being bonded through the equipt. ground.
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| JimmyDee | I got into it big time with a mechanical inspector that removed my ground clamp on the gas line. He insisted that I couldn't use the gas system as a ground. I told him he needed to understand the difference between grounding and bonding. After much discussion, I asked him to call the electrical inspector for some additional input. Needless to say, there was a phone call for me at home by the mechanical inspector asking if I would return to the house and reinstall the bonding clamp to the gas line. Had to tell him that it had already been done.  Jim |
| JimmyDee | quote: Electricman, Yes the duct work is technically grounded through the equipment ground and that should be enough but I have seen so many accidents waiting to happen that I feel it is an additional safety thing to do. Jim |
| Electricman | Jim I kinda had the same expierience with a plumber who said my (ground wire) was going to cause electralisis and burn out his water heater. As hard as I tried to explain that I was just complying with the NEC and that it was a bond and not a ground he would not listen. He even told me that he tells his guys to remove the (grounds) when they see them. Long story short it also took a call from an AHJ to set him staight. |
| JimmyDee | quote: You will have more electralisis without the bond because the current in one side or the other could pass through the water heater. Not using an insulated union and going direct from copper to the steel tank is the worst cause of electralisis there is. Many plummers don't like to use them because of $$$$$$. Jim |
| ricky | When I was a young helper I was on a Hotel going up.One day the sprinkler guy said "hey sparky,that ductwork shocked me." I told my forman who ignored me.So I told another electrician there who I knew from other jobs.He picked up a shop light and arc welded to the ductwork,elec boxes,sprinkler pipes,etc.Turned out that a master eletrician was hooking up the panel and making circuits hot.One of them tripped the breaker so he disconnected the ground and put black tape on it.A drywall screw was found to be the short.Those two electricians were fired the next day.It taught me a lesson about grounds and bonding. |
| wingkwong | quote: |