I recently had a an experience with a spa heater and would like to share, because in many ways it was similar but also a very different and potentially dangerous situation.

We have one of those Bestway Lay-x-spa inflatable hot tubs that are popular in the UK. We're in the US so it goes here by Coleman. This is the kind with the "egg" that contains the pump, bubbler, controller, and heater.

We had a big and sudden thunderstorm, during which the unit was mistakenly left on and the GFCI breaker on the plug tripped. After the storm, the unit tripped the breaker constantly. Tests indicated it was only tripping when the heater was turned on.

I have some experience with electrics, so my son and I resolved to disassemble it and see if we could find the problem.

Inside the unit there is a ceramic heater embedded in an aluminum tube that doubles as both water pipe and heat sink. The heater contains two elements which are comparatively compared to grill or space heater elements.

Unlike your grill, the unit has electronic controls, so we can't simply test resistance at the plug. We took the heater block out and tested both elements with a multi-meter. After figuring out that our first digital multi-meter might be faulty, we were able to test them both at between 80 to 90 Ohms each. To me this seemed a bit low, as tear down videos on YouTube showed other people getting about 250 ohms resistance.

Having some experience with heaters and doing basic research I suspected current may be leaking from the elements and tripping the GFCI. Finding that replacements parts would have to be purchased on the secondary market and imported from UK (on the slow boat), we talked about running the unit disconnected ground, or un-wiring one of the two elements as possible options.

All of these options are a bit risky. The nature of water heaters makes it basically impossible to do tests without the unit connected to water and the pump running. Playing with water and electricity should not be taken lightly - even by experts. We resolved to err on the side of caution and do as many tests as possible.

We put the unit back together in its original configuration and connected it to the spa. We were surprised and delighted to see that now the unit magically stayed on with the heater running - at least for a time. My guess was that the work we did gave some moisture in the heater time to evaporate, or that possibly the GFCI itself had become oversensitive.

Being frustrated that the unit was now working better but still not long enough to heat the pool, we opened it up and disconnected the ground lead only from the heater block itself. The rest of the unit is still grounded. In this configuration the heater runs for hours without tripping the GFCI. This makes me believe the issue is only with current leakage like your grill and not the GFCI plug itself, though the plug does get warmer than I'd expect.

Now of course, chlorinated water is an excellent conductor, and the pump is pushing water right through the aluminum block which is leaking current, so we're keeping the cover on the unit and everyone is warned to stay well away. It cannot safely stay in this configuration forever.

The idea here is similar to yours, that running the heater a while and letting it get hot should "cook" any moisture out of it. We can't put the unit in the over and heat it externally without risk of melting the wire insulation, so that's out.

Ultimately, will it work or not work, who can say at this point. I guess we'll know in a day or two. Needless to say nobody will be jumping in the tub while the ground is disconnected. As we wait for a replacement part to travel halfway around the world, it also makes sense to drop into the local hardware store and purchase a replacement GFCI plug for under $20 just to be certain.

Anyway, thanks for your well written article. It confirmed my understanding of our problem, and it helped my son develop a better understanding of what we were doing and why, as well as the purpose and mechanism behind the earth-fault interrupting circuit. Well done.

Also, to anyone out there with a Lay-z-spa or other consumer grade hot tub who sees a problem like mine, for god's sake, be careful and don't try to do anything with your unit that might not be safe. Otherwise you may be in for quite a shock!

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I just received the meter earlier today, and I like it. It is a great meter for the price and is very well built. I like that it has a good hard plastic cover that fits over the face to keep it protected. I recommend the meter to everyone. Thanks Gerald.

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Hi Gerald,
I'm glad Mr. Yong had this article in the choices on the homepage because I forgot about getting myself the tester. I just went to Ebay and ordered myself one, thanks. I got it for $41.89 US.

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