Bonding conundrum

[iceflow]

Folks,
I’d appreciate some input on my tests. I’ve often wondered whether the copper loop coming out of the ground at the equipment pad is actually connected to the pool shell or anything in the pool and there have been a few recent posts on bonding on this site. Anyway what I’ve done so far is to disconnect the bond loop from the equipment and then carried out some resistance measurements. I find them not what I expected.
• Bond loop to the two pool light metal trim rings – 17 ohms. ( I expected 0 ohms)
• Bond loop to timer box ground bar – 30 ohms. (I expected 0 or close to 0 ohms.)
• Bond loop to pump motor case or heater shell – 30 ohms. (I expected 0 or close to 0 ohms)

I also did some measurements in other areas.
• Pool metal trim rings to the pool light junction box ground wire – 0 ohms. – As expected.
• Timer box ground bar to any pool light metal ring or the pool junction box ground – 35 ohms. I find this very surprising. The motor and pool light cables all run from a common breaker box which is fed from the house mains panel. I was expecting 0 ohms.
• Motor cases or heater shell to timer box ground bar – 0 ohms.- as expected.
I’m thinking that the bond wire definitely does not attach to the pool lights and the 35 ohm measurement between the timer box ground bar and the pool light ground is very strange. The pool is about 25 ft away from the equipment pad, the furthest pool light would be about 60 ft from the equipment pad.

thoughts, comments appreciated.
Thanks

 

[440dodge440]

If you disconnected the bonding wire from the equipment, I wouldn't expect any continuity, at least between the bonding wire and the pump. Do you have any ladders or handrails to check? I saw many of those posts as well and did some checking to the ladder and handrail....

 

[iceflow]

If you disconnected the bonding wire from the equipment, I wouldn't expect any continuity, at least between the bonding wire and the pump. Do you have any ladders or handrails to check? I saw many of those posts as well and did some checking to the ladder and handrail....

Thanks, No, I don't have any ladders. The only metal parts in the pool are the pool light trim rings. They are wired via a GFCI outlet. I tested that the power to the lights was cut when I pressed the 'Test' button on the GFCI. I'll see if there is a way of testing if the bond wire actually is connected to the pool shell, but I'm not holding out much hope. I'd read somewhere that you can test using the pool water, but I'm thinking....'pool water, to the plaster, to the gunite, to the pool rebar or shell to the bond wire'.......not sure that will give me much of a reading using a DVM. It might conduct pretty good in a lightning strike, but not using a 9V battery.

 

[gwegan]

You might want to read the following. How to Test a Swimming Pool Bonding Grid - AQUA Magazine

First where are you? How old is the pool and what exactly are you using to test?


To test the water to the deck (the most important test) You need the deck wet for at least 30 minutes prior to the test.

Additionally you need to do a visiual inspection of all the items in 680.26 (A). Water bonds in the heater don't count. The water bond must be in or adjacent to the pool.

 

[danpik]

A lot of pools use the light niche for the water bond. Short of draining the pool and testing continuity from the niche to the bond wire, there is not a good way to verify it is there. If there is a low OHM reading from the water to the grid, I would suspect there is one in place

 

[iceflow]

Thank you all. The pool is about 16 years old. I've been doing my tests with a Digital Multi meter. I'll take a look at that link and see what I can gather from there. At the moment I'm just measuring resistance from various items to the bond wire loop that comes out of the ground close to the equipment pad.

Thanks