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Thread: Swimming pool bonding.

  1. #1
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    Swimming pool bonding.

    I have a question concerning bonding swimming pool grid . The nec says bond all metal parts on the grid, but it also says you don’t have to bond to service equipment, or the pool panel , or the grounding electrodes. So if the grid is not tied to the service how do you clear a fault? Say I drop 2 wire cord in the water , that’s plugged into a gfci. How will the gfci trip if the water bond does not tie to the service anywhere? I realize that when you bond the pool pump motor that the ground wire from the panel to the motor will tie the bonding grid with the ground at the service. But if you have a double insulated motor, how do the 2 get tied together? I always thought that the number 8 wire from the bonding grid needed to be connected to the ground in the panel but I was told not so . What is your thoughts?

  2. #2
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    The grid is not there to clear a fault. It is there to keep all metal objects and the earth at the same potential. Because of stray voltages you can often have a few volts running in the earth. The equipotential bonding keeps all of the pool area at the same potential. You can't get shocked if everything is at the same voltage
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  3. #3
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    Quote Originally Posted by Rgw 01 View Post
    I have a question concerning bonding swimming pool grid . The nec says bond all metal parts on the grid, but it also says you don’t have to bond to service equipment, or the pool panel , or the grounding electrodes. So if the grid is not tied to the service how do you clear a fault? Say I drop 2 wire cord in the water , that’s plugged into a gfci. How will the gfci trip if the water bond does not tie to the service anywhere? I realize that when you bond the pool pump motor that the ground wire from the panel to the motor will tie the bonding grid with the ground at the service. But if you have a double insulated motor, how do the 2 get tied together? I always thought that the number 8 wire from the bonding grid needed to be connected to the ground in the panel but I was told not so . What is your thoughts?

    Fault at the motor will typically run via the branch circuit EGC to the motor - not the equipotential grid.
    Last edited by Dale001289; 06-05-18 at 12:51 PM.

  4. #4
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    Quote Originally Posted by Rgw 01 View Post
    I realize that when you bond the pool pump motor that the ground wire from the panel to the motor will tie the bonding grid with the ground at the service. But if you have a double insulated motor, how do the 2 get tied together? I always thought that the number 8 wire from the bonding grid needed to be connected to the ground in the panel but I was told not so . What is your thoughts?
    You are correct in your assumption that the grid is required to bond to a min of a 12 awg equipment ground

    "Where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises, this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit. "

    in other words if the # 8 green bond ties the grid to the insulated 12 for the lighting branch circuit than you are good. If however there is no place a 12 insulated equipment ground bonds to the grid than you must bond the equipment ground of the branch circuit for the double insulated pump circuit to the grid


    Exception: Metal parts of listed equipment incorporating an approved system of double insulation shall not be bonded.
    (a) Double-Insulated Water Pump Motors. Where a double-insulated water pump motor is installed under the provisions of this rule, a solid 8 AWG copper conductor of sufficient length to make a bonding connection to a replacement motor shall be extended from the bonding grid to an accessible point in the vicinity of the pool pump motor. Where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises, this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit.

  5. #5
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    Quote Originally Posted by Rgw 01 View Post
    But if you have a double insulated motor, how do the 2 get tied together?
    you extend a min of 12 insulated equipment ground from the pump circuit junction box at the pump location and bond it to the required bonding conductor at the pump location

  6. #6
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    Quote Originally Posted by david View Post
    You are correct in your assumption that the grid is required to bond to a min of a 12 awg equipment ground

    "Where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises, this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit. "

    in other words if the # 8 green bond ties the grid to the insulated 12 for the lighting branch circuit than you are good. If however there is no place a 12 insulated equipment ground bonds to the grid than you must bond the equipment ground of the branch circuit for the double insulated pump circuit to the grid


    Exception: Metal parts of listed equipment incorporating an approved system of double insulation shall not be bonded.
    (a) Double-Insulated Water Pump Motors. Where a double-insulated water pump motor is installed under the provisions of this rule, a solid 8 AWG copper conductor of sufficient length to make a bonding connection to a replacement motor shall be extended from the bonding grid to an accessible point in the vicinity of the pool pump motor. Where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises, this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit.
    I new it had to tie back to the equipment ground somehow to be safe. Thanks for the answer.

  7. #7
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    Quote Originally Posted by david View Post
    you extend a min of 12 insulated equipment ground from the pump circuit junction box at the pump location and bond it to the required bonding conductor at the pump location
    Thanks for the info.

  8. #8
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    Quote Originally Posted by Dale001289 View Post
    Fault at the motor will typically run via the branch circuit EGC to the motor - not the equipotential grid.
    And if the feeder or pump frame loses egc then any fault to the motor case then energizes the whole bonding grid. 240 @ 4mA might be deadly while the gfi just laughs at ya.

    depending on where the pump is, what type of water it uses, how often the pump unit gets serviced, the external egc attached to the pump "lug" can become compromised over time. it for this reason i will take a separate bond wire over to the equipment's nearby disco/sub sub panel and attach it to egc there. thus if the pump loses egc your grid does not, etc.

  9. #9
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    Quote Originally Posted by FionaZuppa View Post
    And if the feeder or pump frame loses egc then any fault to the motor case then energizes the whole bonding grid. 240 @ 4mA might be deadly while the gfi just laughs at ya.

    depending on where the pump is, what type of water it uses, how often the pump unit gets serviced, the external egc attached to the pump "lug" can become compromised over time. it for this reason i will take a separate bond wire over to the equipment's nearby disco/sub sub panel and attach it to egc there. thus if the pump loses egc your grid does not, etc.
    Makes sense to me


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  10. #10
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    Quote Originally Posted by david View Post

    Exception: Metal parts of listed equipment incorporating an approved system of double insulation shall not be bonded.
    (a) Double-Insulated Water Pump Motors. Where a double-insulated water pump motor is installed under the provisions of this rule, a solid 8 AWG copper conductor of sufficient length to make a bonding connection to a replacement motor shall be extended from the bonding grid to an accessible point in the vicinity of the pool pump motor. Where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises, this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit.
    hurmpff.. every time I think I know a little something about the Code ....
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