Customer being shocked in a properly bonded pool

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
This sounds like elevated neutral to earth voltage on the utility primary, but even if that is the case, there should be no shocks occurring if everything is correctly bonded. With everything correctly bonded, the only voltage to drive a shock would be enough current flowing on the bonding system to create a voltage drop that results in a shock.
My thought too. Sounds that something related to the wet nitch not properly bonded.
The short story is, the lighting niche has a lower resistance than the deck/water/handrails. The customer only felt electric shocks when swimming past the light. They did not feel any shock when entering/exiting the pool. I was only able to read 2v to ground, engineer said the day he came they read 7v to ground in the water around the light. This wasn't to the deck, but to plugged into an extension cord leading back to the house. Water to deck its 0v.
When you say lower resistance, in relation to what point? Is all the bonding tied to the GEC system? That could be a source of lower resistance if the nitch is tied both to the EP grid and the GEC while the rest is not. (Parallel paths changing the over all EPB).

If POCO tested to the GEC what they shown was an overall 7V NEV, and the fact you measured only 2V, both possible as at any given moment NEV can change depending on a plethora of conditions. The parallel paths suggestion in combination with a higher NEV would backfeed via connection to the GEC adding the potential difference of 2 to 7V that you measured between the wet nitch and the water/deck bond.
 

jusme123

Senior Member
Location
NY
Occupation
JW
In the interest of safety, the NEC should ban 120v lighting niches in swimming pools, and ban any 120v lighting fixtures within 10’ from edge of pool walls, JMHO
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
In the interest of safety, the NEC should ban 120v lighting niches in swimming pools, and ban any 120v lighting fixtures within 10’ from edge of pool walls, JMHO
The process should be open for submission of Public Inputs (PI) to make changes for the 2026 code soon. It is easy to submit a PI.
 

retirede

Senior Member
Location
Illinois
In the interest of safety, the NEC should ban 120v lighting niches in swimming pools, and ban any 120v lighting fixtures within 10’ from edge of pool walls, JMHO

I’m not sure that would accomplish much. I can’t believe any 120V niche lighting is being installed anymore, and the code is not retroactive. What good is limiting light fixtures while still allowing receptacle outlets at >6’?
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
... The customer only felt electric shocks when swimming past the light. They did not feel any shock when entering/exiting the pool. I was only able to read 2v to ground, engineer said the day he came they read 7v to ground in the water around the light. This wasn't to the deck, but to plugged into an extension cord leading back to the house. Water to deck its 0v.

I think it could be useful in this situation to measure the voltage between two points in the water, one close to the lighting niche and one at least a few yards away from it. This is because a voltage gradient across the water is apparently causing the shocks that are being experienced.
And so reducing this gradient should be the goal of any corrections that are made.

An insulated wire with a bare end could be used to probe the voltage near the light. You wouldn't want the bare end of the wire to be significantly longer than the width of the light, because then it might "short across" the voltage gradient when it's close to the light. Coiling the bare wire to make it more compact would be fine.
 

kwired

Electron manager
Location
NE Nebraska
This sounds like elevated neutral to earth voltage on the utility primary, but even if that is the case, there should be no shocks occurring if everything is correctly bonded. With everything correctly bonded, the only voltage to drive a shock would be enough current flowing on the bonding system to create a voltage drop that results in a shock.
I also agree. If the wet niche were properly bonded to the rest of the equipotential bonding system it would be at same potential as the rest of system. Disconnecting it, all conductors including the EGC should probably result in a change of readings. A elevated neutral to earth voltage would put the wet niche at a voltage above earth. 2 volts is nothing when standing there dry with shoes on and you come in contact with it, but when totally immersed in the pool it is going to be something most people will feel. I've had to find the problem a few times in people's showers when there was only ~2 volts between the water supply and the drain because they could feel it.
 

jusme123

Senior Member
Location
NY
Occupation
JW
I’m not sure that would accomplish much. I can’t believe any 120V niche lighting is being installed anymore, and the code is not retroactive. What good is limiting light fixtures while still allowing receptacle outlets at >6’?
Than change light fixtures to “outlet”
 

jusme123

Senior Member
Location
NY
Occupation
JW
I’m not sure that would accomplish much. I can’t believe any 120V niche lighting is being installed anymore, and the code is not retroactive. What good is limiting light fixtures while still allowing receptacle outlets at >6’?
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Another C10

Electrical Contractor 1987 - present
Location
Southern Cal
Occupation
Electrician NEC 2020
Mike Holt once said he would not swim in a pool with 120 v lighting
Interesting comments about bonding
wasn't there some post in here some time ago stating Mike Holt purposely swims in an energized pool for a lesson of some sort.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I’m not sure that would accomplish much. I can’t believe any 120V niche lighting is being installed anymore, and the code is not retroactive. What good is limiting light fixtures while still allowing receptacle outlets at >6’?
The receptacle will be GFCI protected and there is no direct connection from the receptacle EGC to the pool to provide a path that would permit an elevated neutral to earth voltage to energize the pool equipment and/or pool water.
 

retirede

Senior Member
Location
Illinois
The receptacle will be GFCI protected and there is no direct connection from the receptacle EGC to the pool to provide a path that would permit an elevated neutral to earth voltage to energize the pool equipment and/or pool water.

Agreed. My comment wasn’t intended to convey that a receptacle outlet 6’ from the pool was a bad thing.
 
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