Another Wet Niche Bonding Question

[diyindux]

Well it looks like my electrician screwed up. He did not instal a bond wire inside the conduit. The inspector didn't say anything about it, but I asked the electrician if I needed one and he said no, it is bonded externally. So now I have a pool full of water and no bond inside the conduit to the j-box. Potting one now would be a trick, plus he used 1/2 inch conduit so there is no room for one anyway.

The niches I have are PVC and and have the bond lug that goes through the housing. The fixture screws into a tab that is connected to the bonding lug. The lug is connected to the bonding grid externally so the fixture is bonded. The code required bond wire inside the conduit is insulated and should be fully potted so it is not tied electrically to the inside of the niche or the conduit other than through the exposed portion of the fixture so it seems that the purpose of this bond wire is to tie the j-box base into the bonding grid. If that's the case, wouldn't a #8 wire connected to the metal portion of the j-box and the bond grid serve the same purpose? I'm not thrilled about the idea of draining 15,000 gallons out of my pool and running new conduit so I hope I can find another solution.

 

[Bama Rambler]

Since you have nonconductive niches, your idea of running a bond wire from the j-box to the grid is sound.

 

[diyindux]

Thanks. That was my feeling also. It won't meet the letter of the code but will function the same.

On the j-box, I will replace one of the cover screws with a longer brass screw so it will thread all the way through the base and I will attach a lug for the bond wire below the base. Inside the j-box, I grounded the wiring to the base and used silicone-filled wire nuts so that should be good to go.

By the way, I thought it was interesting how the bonding is considered a separate system from the grounding of the equipment and fixtures yet the two are connected at each location and the j-box. They serve a different function but are fully integrated.

 

[diyindux]

Well I just read something on another forum discussing the bonding wire for the niche and it apparently is there to dissipate any eddy currents that might be created by the electricity flowing within the lead to the fixture. That's why an insulated bond wire works because it is just there to interrupt the field. The wires appear to be twisted within the wire to the fixture so no currents should be generated but if any current is created, the bonding at each end should ensure that no voltage gradient should exist within a space that a person could come into contact with. Requiring this bond wire makes sense to eliminate the possibility of any equipotential gradient within the pool system, but from the standpoint of protecting people it may not be necessary. Of course, any break in the bonding system may allow the generated current to find it's way to a person so I'll need to make sure the bonding system is tested to confirm it is intact.