I recently started a rehab project, and the heater was busted up from expanded water due to the previous owner letting the tub freeze. Rather than paying for a new heater, I tested the old one in a bucket of water. It worked great, but the casing was all leaky. So My plan was awesome. I cut away the old casing and replaced it with new pvc. I had to do some pretty wild PVC manipulations to get the thermistors to fit!

Anyway, when I used my hacksaw to cut out the busted up PVC, I knicked the element. I didn't think too much of it, but low and behold, when I get it all hooked up, the water is now electrified. Deathtrap! So that heater is now going into the trash. Time to buy a new one. BUT MY QUESTION iS, why didn't the GFCI trip? When I go to test the GFCI with the little test button, it trips just fine.

So here we have a heater element that is feeding electiricity into the system but apparently, not enough to trip the gfci? I put a probe on the ground copper and it showed a full 115 volts! And no trip! What's going on here?

I have another question.

Why aren't you grounded?

The GFCI should trip at an imbalance of 5 milliamps between hot & neutral. Even though you have 110v in the water, until the current actually takes another path other than the neutral to complete the circuit, it will not trip. Did anyone feel a shock? Or did you just measure voltage in the water?

This is why it's essential to have a properly grounded heater as well. Even with a heater failure (current leakage), and a GFCI failure, the current still has another path to take.

Another possibility that I've seen from time to time, a bad ground actually brings current into the tub from the house, or another appliance leaks so much current, with poor wiring, bleeds electricity into the gound of the home, ending up first noticed in the spa. After reading that, I sure didn't mean to male such a run-on sentence!

Anyway, you get the gist of it.

Good luck,

~Swine

Why aren't I grounded.....yes...That is the real question, isn't it! Thanks, I'm back to work...

Ok. I think I found the problem. I think the prongs for the gfci are not making good contact with the recepticle. The plastic around one of the prongs is a bit warped from obvious over-heating, which caused the prong to sit back a bit from the other prong. I will change out the GFCI plug.

I am still bothered though. That would mean that a gfci can TEST ok by pressing the little button, but not actually be OK if the ground wire isn't flowing THROUGH the recepticle into the house ground. Is that at all possible?

OK. so, Even though there is a functional GFCI, it won't function if the power leak doesn't go to ground. Since the ground prong on the plug in isn't making contact with the actual ground receptacle, the current flows through the water and back to neutral, so the GFCI doesn't trip.

Question #1: why didn't it trip when I got buzzed by touching the ground copper?

Question #2: Does it seem like a bad design to have all of your hot tub groundings relying on a single prong of a plug? Wouldn't it be more safe to hard wire the ground lug to a ground source?

I don't like this notion that a GFCI can appear functional yet do nothing if the ground prong is loose.

The GFCI shouldn't need a ground to work. The imbalance between hot and neutral is what trips it. The ground is there for safety redundancy in case of a GFCI failure.


Perhaps you didn't touch the wire long enough? It takes about 1/20th of a second (the length of the sine wave@60Hz) to trip.

However, in a properly grounded hot tub, you would have never felt a thing, even with a failing heater and non-functional GFCI.

Apparently, your body made a better ground than the actual bonding wire. This isn't good. Additionally, since we know the heater is borked, it should have tripped the GFCI instantly with a good ground, before anyopne had a chance to put their little feet and fingers in the spa. (Ironically, once in the spa, they'd be perfectly safe. However, once they put one leg on the ground, OUCH!)

Measure for volatge at the bonding wire. Also, replace the GFCI just in case.