Customer shocked entering hot tub that sits on pool deck.

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brantmacga

brantmacga

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Thought I’d share this one.

I did the wiring installation for the hot tub 14/yrs ago while the pool was still under construction. The original HO worked for the tub manufacturer, which is why they didn’t do a built in spa.


Anyway, new HO calls me, they feel voltage entering and exiting the spa. They’ve lived here 4/yrs and this just started.


Here are pics of install

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I.
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Pool water to pool deck = 0v
Pool deck to stairs = 0v
Spa water to stairs = 2v
Spa water to extension cord ground = 2v
Pool deck to extension cord ground = 2v

Turn off the house main, still reading 2v to ground.


The primary cause here is that the pool contractor did not run a bonding wire to the pool equipment, which means it didn’t connect with the house service via pump wiring EGC, so the spa EGC is electrically isolated from the pool deck.

When I was called in to do the original wiring, the pool was incomplete, but the concrete deck was already poured. The city even back then inspected for bonding, so I don’t know how this got away. I dug all around the equipment pad and did not find a bonding wire.


My plan is to drive electrodes around the pool deck horizontally to the shell of the pool and connect all of them back to the house service.

I also spoke with utility engineer, they might investigate the source. No definitive yes on that yet.


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I bet it is the power company underground or perhaps a neighbors outdoor wire. If you still have the voltage after you turned off the main then it is obviously not coming from the service. I be curious to disconnect the neutral and see what you have
 
Either a neighbor, crack in primary or secondary wiring, or street lighting.

I asked utility about disconnecting neighbors momentarily while checking voltage; didn’t sound like they were willing to do that.


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hillbilly1 said:
Might also check at night, may be a bad uf cable to a pole light that is switched at the source. Did the customer say what time they use it?
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I was there at 5pm yesterday and measured voltage.

And yes I have the amprobe AT-3500 but I don’t think it will find this.


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Typo in original post….. from pool water to pool deck is 0v.

Anyway, back out here this afternoon. Here are pics of various voltage tests

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hillbilly1 said:
Might also check at night, may be a bad uf cable to a pole light that is switched at the source. Did the customer say what time they use it?
Click to expand...
Is your point that there may be a much higher voltage at other times due to something being on a timer? Street lights or private light on a pole that is likely off when he's checking? That's what I was wondering anyways. Often times people like to use their tubs at night when exterior lights may be activated, troubleshooting is probably going to happen during normal business hours when exterior lights are likely off.

Pardon my lack of experience but this has me interested. Would 2 volts normally even be noticeable? Are there other factors that would make 2v more noticeable?
 
Have you watched Mike Holts bonding pool equipment video and check out his real live test on his own pool.
Your 2 volts sounds just like the readings he explains is very common due to power company neutral currents traveling thru the earth, especially when bonding is missing around the pool/hot tub deck.
 
You might also poke a screwdriver in the ground at various locations in the yard and measure the voltage between it and the extension cord EGC. You can then see if it stays about the same or if the voltage changes depending on where you are.

Disconnecting the service neutral conductor in the main panel like Dennis mentioned and checking if the voltages change is a good idea (obviously with main breaker off). If you do this you could also measure the voltage between neutral and GEC/EGC. With the neutral connected you might check if you can detect any current on the service neutral with a clamp meter when the main breaker is off.
 
when you're in water you can feel small voltages. I was called to an outside shower that was mildly buzzing people and I measured 4 volts from standing area to copper pipes. I drove ground rod at standing area and connected it with wire to copper pipes. voltage gone
 
brantmacga said:
I’m not familiar with this one


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Click to expand...
Deadly accurate when tracing live circuits. Instead of injecting a signal like other circuit tracers, which tend to bleed onto other wires, that tracer draws a pulse off the line, so it traces back to the source, instead of both ways, and onto other lines. I can take a bundle of 50 conductors, and pull out the correct one 99.9% of the time. If it is the customers panel, it will trace back through it, if it is the utility it will show up there instead. Same way if it’s the neighbors. If you walk up to the meter on their house, and it sounds, it’s coming through their lines.
 
Joe.B said:
Pardon my lack of experience but this has me interested. Would 2 volts normally even be noticeable? Are there other factors that would make 2v more noticeable?
Click to expand...

It is EXTREMELY uncomfortable. It’ll make you jump back.

Edit to add…. When you’re the path between 2v and ground. If standing in shoes you don’t feel it. Put your wet feet or hands on the deck and touch it, and it stings


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I’ve got three rods in the ground under the deck connected to pool pump and pool panel. No change. My plan now is to drive electrodes into the steps around the spa and concrete them back in, then connect those rods to the ground bar inside the spa.


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I don’t know if two volts will be enough to power that tracer I was talking about though. Lake Lanier has two volts on it due to all of failing underground lines.
 
hillbilly1 said:
I don’t know if two volts will be enough to power that tracer I was talking about though. Lake Lanier has two volts on it due to all of failing underground lines.
Click to expand...

I’ve heard that, probably from you on this forum? My neighbor who is also an EC is building a house up there right now. I’ll mention it to him.


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