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Thread: Gas water heater ground

  1. #1

    Default Gas water heater ground

    I am redoing my kitchen and thought it would be easier to replace the copper lines with PEX so it can go snake down the basement water heater easier.

    1) I have a gas water heater, why is there a ground wire between the cold and hot copper pipes about 12" above the water heater? Isn't the heater it self metal? And it is sitting on the ground already so what is the reason for the short ground wire between the pipes for grounding?

    2) If I do replace the kitchen cold and hot pipes with PEX tubing and connect them to the top of the current water heater what else needs to be done to meet code? I assume now the kitchen faucets are no longer grounded. If this will cause me more problem than I will run it with copper pipe instead of PEX.

    thank you.

  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default heater

    I install the "jumper" between the hot and cold lines BECAUSE the heater is metal if water heaters in a particular house seem to fail too frequently. It is my belief, valid or not, that when water heaters fail within a few years of installation, especially if it happens to more than one, that there are residual currents leaking into the hot water piping. As these currents, and they are not detectible by common means, gravitate to the cold water pipe and then to the earth, they eat away at the stell water heater shell. The jumper lets the currents bypass the heater. This may or may not increase the life of the water heater, but I had one house where one heater failed. I installed a new one, and in a matter of months it also failed. The top of the water heater looked like someone had taken a can opener to it from the hot pipe to the cold one. I installed the new heater AND a jumper, and it has lasted at least 8 years now.

  3. #3
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by hids2000 View Post
    so what is the reason for the short ground wire between the pipes
    Because someone don't understand just what is meant by bonding as outlined in 250.104 of the NEC
    There is no requirement to be found anywhere in NEC for the past 25 years for this stupid installation.
    This bond serves no practical purpose.
    This bond is a waste of time and material
    This bond is due to the lack of education

  4. #4
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by hj View Post
    I install the "jumper" between the hot and cold lines .
    In the state of North Carolina you would be fined for this practice as a plumber is not allowed to make electrical installations.
    Understanding a parallel circuit would let you see that the jumper does nothing to prevent current from flowing from the hot to cold through the tank should current be applied to the water pipe.
    The train of thought that current somehow leaks out the ground is completely unfounded and forbidden by the laws of physics.
    The laws that govern current flow state that every electron that leaves the transformer and entering the house must return to the transformer so no electron can leak out anywhere especially to earth.

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    As I understand it, if you want to use pex, you will need (I think) at least 18" of copper at the top of the WH before you transition to pex. This is to protect the pex from overheating caused by the flue.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6

    Default

    So if I leave at least say 2ft of copper on the hot side of the water heater than to PEX tubing I will have no problem with any electrical codes for the kitchen sink and faucets not grounded?

  7. #7

    Default

    Electrical things can malfunction. A stray wire can touch something metal.

    Like a stray stranded wire inside a range can touch the metal cabinet.

    Or heat can melt the insulation off of a wire and the wire can touch something metal like a water pipe or a gas pipe or a metal heating vent.

    And things like water heaters have plastic pipes inside and use rubber grommets which electrically isolate the cold water pipe from the hot water pipe. Also some water meters can electrically isolate the house side from the street side due to rubber grommets being used. So might see a ground jumper across the water meter too.

    With that said, it is a good idea to electrically "bond" to ground metal things like pipes, metal vent systems, metal cases of appliances, etc.

    Then should a "hot" electric wire accidentally touch the metal object, this will cause a short to ground and the breaker will trip. Or it will keep the metal object at "ground potential" and not be a danger to anyone touching the metal object.

    And the danger is with something like a plumbing system with pipes running all over the place. Lots of opportunity for something electric to malfunction and energize ALL the metal pipes!

    BUT if you are installing plastic pipe to the hot and cold side of the kitchen faucet, then this would electrically isolate the faucet from the other pipe system - So not to worry!

    The faucet itself does not have any electrical components, so no risk of an electric wire touching that faucet (and someone touching the faucet and being shocked).

    So basically a common sense sort of thing - added safety in case something should malfunction.

    Note: I read somewhere that common sense was not so common!

    P.S. Be sure when replacing metal water pipe with plastic pipe that you are not disrupting your main electrical system ground. These used to be only connected to a cold water pipe ground. These days a ground rod or two is required. Ask your local electrical inspector or an electrician.

    VERY important to have a good main electrical system ground!

  8. #8
    Electrical Contractor/Instructor jwelectric's Avatar
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    If there is 10 feet of metal water pipe in contact with earth then the grounding electrode conductor must be connected within the first five feet where it enters the building see 250.52 (A)(1)

    If there is a “complete” metal water piping system on the interior of the building then a bonding jumper must be installed at any accessible point on the metal water pipe see 250.104(A)

    If the metal water piping system is not a complete metal water piping system then the equipment grounding conductor installed with the branch circuit that is likely to energize the pipe can do the bonding see 250.104(B)

    Nowhere in the NEC does it require the hot and cold pipes to be bonded together nor any metal duck work or any other metal that is not an appliance that has electricity ran to it.

  9. #9
    Homeowner Thatguy's Avatar
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    Quote Originally Posted by hids2000 View Post
    wire between the cold and hot copper pipes about 12" above the water heater?
    Turn on a lot of stuff in your house and measure the current in this wire. If it's not zero it must be doing something.

  10. #10

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    250.104 (A) - "Metal water piping system"

    What does that mean? Cold only?

  11. #11

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    The following are the kind of things which can happen. Could these accidents have been prevented?

    "metal duct and vent tested positive for 110 volts"...
    http://www.clickorlando.com/money/7302637/detail.html

    "The wiring had to be in the exact position, the duct work installed - installed completely to code - but over time they were close enough together to rub and it rubbed in the exact spot on the wiring to reach the hot wire"...
    http://www.montanasnewsstation.com/g...Type=Printable

    "This year an appliance installer died from electrocution due to an energized metal framing member that came in contact with the metal duct that was connected to the appliance"...
    http://74.125.155.132/search?q=cache...&ct=clnk&gl=us

    "hidden power lines and metal duct-work are a constant risk for worker's electrocution"...
    http://www.air-techinternational.com/homeprep.html

  12. #12

    Default

    The water piping SYSTEM needs to be BONDED. When used as a grounding electrode and connected within 5' of the entrance, only the cold water side is bonded. Many water heaters have dielectric connectors or bushings that do not connect the hot to the cold. If you have a shower, the mixing valve is all you need to connect the hot side with the cold side. If you don't have an all metal mixing valve then the bonding jumper between the hot and the cold is required and is to be size accordingly. This is not to be confused with the bonding that is required when you have an appliance connected to the electrical system and gas.

    When you see the jumper, it may or may not be needed but in some cases it is. If you have a pex or plastic supply system and only small areas of copper that are isolated to the components they serve then they will not be required to be bonded.
    http://www.inspectpa.com/forum/forum.php
    My answers are based mostly on the ICC codes. Advice given is my personal opinion and every person performing work should acquire a permit from his/her jurisdiction and get the work inspected. My opinions are not directions to follow for DIYs or professionals

  13. #13
    Moderator & Master Plumber hj's Avatar
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    Default jumper

    The heater is a "high resistance" circuit, (because it has to use the water to complete the circuit since the dielectric devices are preventing a direct metal to metal path), and the jumper is a low resistance one, therefore, the current is going to seek the easier path. You mean that a plumber cannot change an electric water heater in your state unless he has an electrician disconnect it, then come back and reconnect it after the installation? Your heaters must be enormously expensive to change. I hope you do not have "gas fitters" who are the only ones permitted to work on gas piping, or the gas heaters would be the same way. There have been times when I have done almost as much electrical work, even trouble shooting circuits for electricians, as plumbing.

  14. #14
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Billy_Bob View Post
    The following are the kind of things which can happen. Could these accidents have been prevented?
    Yes! The equipment grounding conductor for the air handler would have carried the fault current back if the installation had been installed correctly.
    I didn’t read the article and don’t plan to read the article but anyone with any common sense would know if the duck work rubbed a bare spot in a nonmetallic cable then both the cable and the duck was installed incorrectly. Why was the duck work moving around in such a fashion that it would damage the cable? Could it have been installed in a fashion that would allow movement?
    Why was the nonmetallic cable installed in contact with the duck?
    Either or both of these could have been installed incorrectly which would have caused the duck to become energized.

    Quote Originally Posted by jar546 View Post
    If you don't have an all metal mixing valve then the bonding jumper between the hot and the cold is required and is to be size accordingly.
    Can you provide a code reference that requires this type of silly installation? Before you answer look closely at the plumbing codes and see just how many different piping systems that are allowed to be installed in a dwelling unit. See if the plumbing code calls out a difference between hot and cold potable water.

    Quote Originally Posted by hj View Post
    The heater is a "high resistance" circuit, (because it has to use the water to complete the circuit since the dielectric devices are preventing a direct metal to metal path), and the jumper is a low resistance one, therefore, the current is going to seek the easier path.
    This is a false statement as current will take every possible path available to it.
    If current always took the path of least resistance how can a human ever feel electrical shock? Wouldn’t the current choose to travel on a path of lesser resistance?

    Quote Originally Posted by hj View Post
    You mean that a plumber cannot change an electric water heater in your state unless he has an electrician disconnect it, then come back and reconnect it after the installation? Your heaters must be enormously expensive to change.
    Yes unless the plumber has an electrical license then they are required to hire an electrician to disconnect and reconnect the electrical circuit.

    Quote Originally Posted by hj View Post
    I hope you do not have "gas fitters" who are the only ones permitted to work on gas piping, or the gas heaters would be the same way. There have been times when I have done almost as much electrical work, even trouble shooting circuits for electricians, as plumbing.
    Plumbers can also install gas lines if their license covers gas piping. If not then they must enlist the aid of a licensed HVAC installer.

  15. #15
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Billy_Bob View Post
    250.104 (A) - "Metal water piping system"

    What does that mean? Cold only?
    It means the potable water and the bonding conductor is to hit at any point on either the hot or cold water pipe at any point that is accessible

    (A) Metal Water Piping. The metal water piping system shall be bonded as required in (A)(1), (A)(2), or (A)(3) of this section. The bonding jumper(s) shall be installed in accordance with 250.64(A), (B), and (E). The points of attachment of the bonding jumper shall be accessible.

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