Electrical jolt from water in hot tub

txborn · Mar 28, 2010

I have a beachfront condo in Mexico on an upper floor that has a fiberglass hot tub placed on the tile balcony. It is about 3 years old. We just got an email from a recent guest saying that they used it every night but on the last night they touched the water while standing on the tile and received a nice little jolt. There is a condo next door that has the same issue with their unit and I personally experienced the jolt from their hot tub last time I was down there. The heater and pump were running. I don't know if it still happens if the heater/pump is off - I never tested it that way.

I will be headed down there next month to attempt to troubleshoot but based on our neighbors unit, the problem is intermittent. Can anyone shed some light as to what may be causing this?

PoolGuyNJ · Mar 28, 2010

Bad ground and the lack of a GFCI, I expect. Good luck finding the cause of the bad ground. I strongly urge you shut the tub down until the building's authority finds and corrects the cause.

Scott

cheddar85 · Mar 28, 2010

PoolGuyNJ said:
Bad ground and the lack of a GFCI, I expect.

Most likely. If that ever happened with mine, I'd probably turn around and sell it! I've been shocked more than enough in my lifetime! Not every time was my fault though... :shock:

txborn · Mar 29, 2010

I don't ever recall seeing a GFCI breaker box on pool/spa equipment much less on receptacles near sinks. I am considering getting a GFCI load center and taking it down to replace the factory non-GFCI one.

Ohm_Boy · Mar 29, 2010

You can add a GFCI (and you should) but you'll still have to find where the electricity is leaking off. The GFCI will prevent people from getting a jolt, but it will do it by preventing the hot tub from running. Somewhere, a live electrical conductor is allowing leakage current to flow into the water, which then becomes energized with respect to the tile floor. Or vice versa - the floor is energized and the water is the ground reference. Doubtful, but sometimes you have to think that way. So basically, the motor, heater, lamp, temperature sensor, or some other electrical component is making electrical contact with the water. You may be able to actually detect this voltage with a meter. If you cannot find a metal 'in water' point to connect a meter lead to, clip a lead to a small piece of copper (small pipe elbow or a penny) and place it in the water. Touch the other meter lead to a ground point. You should see a potential between the two. You may try disconnecting devices in turn and rechecking to see when the potential goes away (power off to work, back on to test). That should help identify the faulty component.

If the "touchable" components of the unit are grounded, then the theory is that the breaker would trip when an electric leakage path occurs, if the leakage path is substantial enough. (Assuming a properly grounded electrical distribution system, this is Mexico, right?). That's the whole reason that one side of our electrical system is grounded in the first place. GFCI devices are designed to trip for the leakages which are less than required to trip the breaker.

larrys1 · Mar 31, 2010

I had the same problem. Had a cement slab poured for hot tub. Wired up tub with GFCI. Works great. Then I noticed when I was standing next to the tub on the cement and put my hand in the water, I would feel a "tingle". It would be the same kind of feeling you receive when touching a 9 volt battery to your tongue. Not a serious jolt. Find out from them if this is what they're feeling and not a shock. Ended up being "stray" voltage leak through the ground and up through the cement slab. I was told I should've had the cement guy tie the rebar differently (equipotential bonding). So for us it's still there. Can't seem to do anything about it. Still use the tub as the GFCI circuit works fine, etc. Try looking up stray voltage hot tub on google.

txborn · May 17, 2010

Sorry for being AWOL on this thread for so long - been out of town a lot and researching getting a new replacement spa (new thread coming up on that). Thanks for all the advice. The problem seems to have been caused by a severely corroded heater element/housing. The heating coil looked like it was opened up by a small explosive

Housing was very rusted as well. They replaced both and there have been no issues since. Problem is, that element fails about once every 30 - 45 days and has to be replaced. That old spa is used daily year round by guests so has taken a lot of use over the last 4 years.

Bama Rambler · May 17, 2010

I'm glad you found out what the issue was.

I have an RV so I'm also on RV forums and one of the big issues for tripping the GFCI is the water heater element corroded thru. I'll keep that in mind when dealing with GFCI issues and an electric heater is involved.

txborn · May 17, 2010

Bama Rambler said:
I'm glad you found out what the issue was.

I have an RV so I'm also on RV forums and one of the big issues for tripping the GFCI is the water heater element corroded thru. I'll keep that in mind when dealing with GFCI issues and an electric heater is involved.

LOL, my issue was there was no GFCI at all. Not required in Mexico I guess. New spa (110 VAC) will have a 20 amp GFCI breaker, new wiring and a GFCI on the spa power cord. Will be down there in June to install myself.