Customer shocked entering hot tub that sits on pool deck.

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brantmacga said:
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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Can you use a low impedance voltmeter? If you’re measuring ground from two separate locations but common in the service panel, then you’re measuring a gigantic loop and any induction happening within it. A low impedance voltmeter will drain down any weak sources of voltage.
 
Xptpcrewx said:
Can you use a low impedance voltmeter? If you’re measuring ground from two separate locations but common in the service panel, then you’re measuring a gigantic loop and any induction happening within it. A low impedance voltmeter will drain down any weak sources of voltage.
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I don’t have a LoZ meter, but I’ve put my hand in the tub while touching the steps …. It’s hot.


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synchro said:
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.
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I did the screwdriver test all over the yard and up near the padmount out front; voltage reading on my meter was 2v everywhere.

I’ll do a test of neutral current tomorrow. The only thing I’ve done with the service so far is to disconnect and check for voltage at pool, which still existed with power off.


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Interesting, sounds like the neutral and ground at the service is what’s at potential. Underground power? Just started shocking people? Sure sounds like a failing neutral on the service. Maybe you can check resistance between the pad mount (assuming it’s a pad mount transformer) and the meter base with the load off. Calculate what the actual resistance would be, and see if it’s high.
 
hillbilly1 said:
Interesting, sounds like the neutral and ground at the service is what’s at potential. Underground power? Just started shocking people? Sure sounds like a failing neutral on the service. Maybe you can check resistance between the pad mount (assuming it’s a pad mount transformer) and the meter base with the load off. Calculate what the actual resistance would be, and see if it’s high.
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When I disconnect their power, the voltage is still there. So I don’t think it’s coming from this house.

Also today I checked for voltage between the equipment pad and pump, sure enough, 2v. I touched the pool pump and wet equipment pad and felt a tingle. The pad is wet because the seal is leaking on the pump. After finding that today, I’m going to insist to the utility they also investigate. Because at this point it seems you can touch any grounded equipment while in contact with the earth and get shocked.


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brantmacga said:
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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Bonding wire doesn't go back to panel. Should have equipotential bonding of metal around pool and hot tub
 
brantmacga said:
When I disconnect their power, the voltage is still there. So I don’t think it’s coming from this house.

Also today I checked for voltage between the equipment pad and pump, sure enough, 2v. I touched the pool pump and wet equipment pad and felt a tingle. The pad is wet because the seal is leaking on the pump. After finding that today, I’m going to insist to the utility they also investigate. Because at this point it seems you can touch any grounded equipment while in contact with the earth and get shocked.


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Yes, but are you disconnecting it at the transformer? You still have a live underground feed to the meter.
 
I went back today; I pulled the meter and disconnected the neutral, and still have the voltage at tub. Checked all connections and meter and load center. It’s a 3-wire service.

I haven’t been able to fully solve this yet.

I drove 5/8”x 8’ rods at each and and the center of the pool horizontally under the deck. I connected all of these with a #8 and trenched it back to the pool pump and panel; no change.

I drilled holes into the back of the concrete steps on the side facing the tub. I drove rods into the steps and concreted them in, connected with #8 to the spa ground bar; dropped from 2v to 1v.

I will ask the utility to come Monday.


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ptonsparky said:
Could you measure a current flow at the connection to pool pump and panel?
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0.1A according to my meter. I don’t know if that’s the minimum display reading or if it’s actually 0.1A.

Edit…. I can’t remember exactly where I took the measurement; I did so many different tests. I think when I read 0.1A, it was from a #8 I landed on the spa ground bar to one of the grounding rods I’d driven nearby just to see what sort of readings I could get. Which makes sense to get it there as the current flow was happening between the deck/ground and spa water.

If I float the EGC from the house panel to the spa, there is no current flow from the deck to the spa.


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LarryFine said:
Why not see if the other people sharing the transformer will consent to a short-term power shut-off?
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I did think about that. I was concerned the neighbor might misunderstand what I’m trying to do and think I was laying blame on them for the issue, and I didn’t want to cause an issue between neighbors. I felt it would be more appropriate for the utility to intercede.


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brantmacga said:
I was concerned the neighbor might misunderstand what I’m trying to do and think I was laying blame on them for the issue, and I didn’t want to cause an issue between neighbors.
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Assure them the opposite s the case, that you want to make sure your issues aren't being transferred to them.

And that this will help the POCO troubleshoot the problem, which would also go toward assuring their safety.
 
brantmacga said:
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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It could be more Than 2 volts as the resistance changes because your reading through the wet earth
 
Might be chasing your tail trying to eliminate the voltage present as you seem to have already more or less ruled out local issue at HO panel/meter. Your big issue, and the reason for requiring it, is the missing EQ bonding related to the hot tub. If all properly bonded you could actually have 120V present in a remote to bonded surface and still be 0V between any bonded surface. (see Mike Holts videos on pool bonding.) There is reference in his video that voltage, NEV, can be related to POCO even miles down the road. You've seen the effect of proper bonding with 0V between the deck and water, and 2V between remote and deck, meaning the 2V is present but the EQ is working (bird on the wire effect). While I would agree ideally is to eliminate any voltage, it may not be practical or even posible, again the reason for the EQ bonding be done correctly. And even if a change as a result of neighbors or POCO fault is to suddenly worsen, the EQ would maintain pool safety.
Another thing to consider I have heard of bonding having been done correctly, only to have a contractor cut it when doing some work such as those relief cuts in the concrete. That may be from the one picture it looks to have deck cut out to recess the hot tub. Another thing was hot tub recently replaced? Perhaps bonding never got reattached or was damaged when replaced.
Your comment to drive under slab rods to bond is unnecessary, your 0V from water to deck and stairs indicates bonding, the issue, from your stated voltage readings, simply lies with the hot tub not bonded to the rest of the pool and decking.
Try this, run a temporary cord connecting from hot tub bonding location to the pool equipment bonding effectively recreating the bonding that should be present, and test the hot tub numbers, this will confirm if bonding at issue. If voltage goes away then you have your answer and it may require chipping the concrete to get to the pool bonding to tie it in.
 
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