Tripping hot tub breaker

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WSB123

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I have a customer with a 50 amp / 240 volt hot tub. The tub was tripping the breaker and the hot tub company replaced the motor. The tub would run for a few minutes, but then would trip.
It now trips as soon as the motor is turned on. After replacing the motor with the same results, he has replaced the circuit board as well. The breaker still trips. The lights will turn on without issue.
As the electrician, I looked at the tub after the other guy came to the end of what he knew to do. I have not done a thorough search, but the first thing I did was to disconnect the ground wire at the tub. The motor runs. At that time, I checked the voltage between the neutral and ground - 0 volts. As soon as the ground wire is connected, the motor trips.
The customer has had several electrical issues due to poor workmanship in the past that we have already remedied, so he asked us to replace the supply wire from the panel to the hot tub disconnect and to the tub. I told him replacing the incoming line to the breaker would not alleviate the problem because the breaker is detecting ground faults south of the breaker, not the incoming line, but we replaced it for his peace of mind.
The hot tub technician called tech support for the tub and they think there is an electrical issue within the house. Tech support recommended turning off all breakers to see if power was feeding back to ground.
My first question: If this were an issue, wouldn't it cause other ground faults to trip? (hot tub tech support says voltage going back to ground would not necessarily trip the ground fault receptacles, because they are different from the hot tub breaker - How so? ) By the way, with all breakers off, the hot tub still trips.
Second question: What is the best way to check the system for any "voltage leaks" if there are any? I am not getting any readings between neutral - ground.

Thank you for your input.
 
First, check the heating element. Disconnect it entirely.
You need a meter for reading high resistance. A Mega ohm meter.
Moisture on the circuit board will cause problems.

Disconnecting the EG wire proved that the GFCI is doing its job and the path of the fault is through the EG, not earth. Faults on the line side of the GFCI have nothing to do with it tripping.

No readings between Neutral and Ground most likely means you do not have a neutral load and you do not have a meter that is capable of measuring at the level a GFCI operates..

Edits:
Tech support did not know what they are talking about.

You are looking for current flow not voltage
 
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Little Bill said:
This ^^^^^^
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^^^^^^ X2, assuming it is not a gas heated hot tub.

The reason is that in many designs, there is a contactor for the heating element set up so that the heating element is only allowed to be powered when the pump motor runs. This prevents it from boiling water that can scald someone. So with the motor not running yet, no power on the heating element, no GF. As soon as the heating element is energized, the tiny crack in the ceramic insulator lets voltage leak into the water and the GFCI trips. You can prove it by just disconnecting the heater leads. There will be a terminal block and maybe some fuses for the heater, disconnect them, then let the motor run. No GFCI trip proves it was the heater element. Hot tub guy should have known this test technique...

There is no "fixing" that heater element, it needs to be replaced. Tell the owner NOT to go with the cheapest thing he can find, it will not last long either. Then let the Hot Tub tech replace it... that job is one ROYAL pain in the rear! The heating element is buried in a stainless steel tube in the PVC plumbing system, often right behind the control panel, which is mounted to that SS tube. But in my experience, they are buried so deep in the system that you basically end up disassembling the main plumbing system almost entirely just to get at it. So it's a 90% plumbing job, 10% electrical, and all done on your knees with no room to work...
 
Count me in as well - element failure is probably the issue about 90% of the time when hot tubs are tripping GFCI's.

I would have checked element before checking much of anything else.

If you can't measure it for some reason simply disconnect the element and then run the tub. If it holds in that condition that is your problem.
 
kwired said:
Count me in as well - element failure is probably the issue about 90% of the time when hot tubs are tripping GFCI's.
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You would think that the hot tub service tech or at least the tech support from the manufacturer would know this, wouldn't you?
 
growler said:
You would think that the hot tub service tech or at least the tech support from the manufacturer would know this, wouldn't you?
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One would think so. But if they get convinced there is a pump issue it can be hard to get their mind off that as well. GFCI trips shortly after pump starts -they may only see the pump and forget the element isn't supposed to come on until there is proof of pump running.
 
kwired said:
One would think so. But if they get convinced there is a pump issue it can be hard to get their mind off that as well. GFCI trips shortly after pump starts -they may only see the pump and forget the element isn't supposed to come on until there is proof of pump running.
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What I was getting at is that the hot tub service people should see many of these problems, it's what they do for a living.

For an average service electrician hot tubs are a really small percentage of their work.

What tech support is for is to give the field service tech a run down all on the problems that could cause said symptoms. It's kind of hard to believe they have not thought of the heating element.
 
growler said:
What I was getting at is that the hot tub service people should see many of these problems, it's what they do for a living.

For an average service electrician hot tubs are a really small percentage of their work.

What tech support is for is to give the field service tech a run down all on the problems that could cause said symptoms. It's kind of hard to believe they have not thought of the heating element.
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Well I don't have much experience with hot tub tech's other then at initial installs at times.

I can tell you about some cases where appliance repairmen tell customer they need to have an electrician check out the tripping GFCI, as it must have a problem. Then I show up and have to find that faulted part inside the appliance because they don't understand how/why GFCI's work. I honestly don't see a spa repairman being much different, especially if he doesn't have much experience working on them. I'd bet a lot of them don't really know much about why a faulting component can make the GFCI trip. Tech support depends on if you talk to someone that actually knows how things work or if you are talking to someone that knows how to look things up on a computer, you need to ask the right questions to get the right answer with the latter.
 
I see a lot of companies hiring "technicians" off of the streets with little to no experience. My step-brother-in-law got a job as a hot tub / spa technician, he had no idea which end of a screwdriver to hold... That guy went through jobs like I go through cheap shoes; he rarely outlasted the probationary period. Yet after 2 days of shadowing another technician, they sent him out in the field. I know, because he was constantly calling ME to help him troubleshoot. Luckily for me, he only lasted 2 months on that job. My point though is that I'm not at all surprised that he didn't think of that.

Or he DID, and knowing what a PITA job it is to change it, he was hoping the OP would do it!
 
After checking the heater, try looking at the ozonator if one is installed. This is usually an ultraviolet light package used for 'sanitizing' the water. The circuit board fails, over time, causing a L-G fault.
 
The symptom of the GFCI initially tripping shortly after the motor starts and later tripping immediately on starting is consistent with a heating element fault.
The heating element leakage could have been showing up only as the element temperature increased, but then became a permanent fault.

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Guys, I am sorry, but I forgot to mention that I have already disconnected the element. I went out there a month ago when the spa guy could not make any headway and did not think about it when I posted yesterday. I disconnected the ground conductor and discovered that the motor would run while disconnected. I removed the leads to the element, but when I touched the wire back to the ground bar it would trip.
I got involved again last week when the customer asked us to replace all of the wiring. A unnecessary thing to do, but he said it was worth it to him to eliminate it from his mind. Now that the wire has been replaced, the tech support is saying that there must be voltage leaking to ground from elsewhere. I agree with y'all that the tech support guy is wrong.
Beyond the element, what do you recommend checking next?

Thank you for your replies to this post.
 
WSB123 said:
Guys, I am sorry, but I forgot to mention that I have already disconnected the element. I went out there a month ago when the spa guy could not make any headway and did not think about it when I posted yesterday. I disconnected the ground conductor and discovered that the motor would run while disconnected. I removed the leads to the element, but when I touched the wire back to the ground bar it would trip.
I got involved again last week when the customer asked us to replace all of the wiring. A unnecessary thing to do, but he said it was worth it to him to eliminate it from his mind. Now that the wire has been replaced, the tech support is saying that there must be voltage leaking to ground from elsewhere. I agree with y'all that the tech support guy is wrong.
Beyond the element, what do you recommend checking next?

Thank you for your replies to this post.
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Actually he is right in that there is voltage leaking to ground elsewhere. What both of you have so far failed at is figuring out where.

Exactly what wire were you touching back to the ground bar? Main EGC feeding the tub or the EGC of a component in the tub, or something else altogether.

Make sure you have no neutral to ground faults anywhere.
 
WSB123 said:
Guys, I am sorry, but I forgot to mention that I have already disconnected the element. I went out there a month ago when the spa guy could not make any headway and did not think about it when I posted yesterday. I disconnected the ground conductor and discovered that the motor would run while disconnected. I removed the leads to the element, but when I touched the wire back to the ground bar it would trip.
I got involved again last week when the customer asked us to replace all of the wiring. A unnecessary thing to do, but he said it was worth it to him to eliminate it from his mind. Now that the wire has been replaced, the tech support is saying that there must be voltage leaking to ground from elsewhere. I agree with y'all that the tech support guy is wrong.
Beyond the element, what do you recommend checking next?

Thank you for your replies to this post.
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You need a megger to check the motor. Look at the circuit boards. Do you see signs of water or moisture even though every thing is dry now? If the relays are removable pull them out and look at them and the base.
 
This is a process of elimination. You need to find out what you need to disconnect so the breaker won't trip, one item at a time.
 
I agree with all of the suggestions and I second the recommendation on checking the ozonator. I had a similar call for tripping breaker and that's what it turned out to be.
 
WSB123 said:
I disconnected the ground conductor and discovered that the motor would run while disconnected. I removed the leads to the element, but when I touched the wire back to the ground bar it would trip.
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Did you check to see if the motor winding could be shorted to ground? I know it's a new motor but it is possible to get a bad one, at least I guess it is ( they are probably made in China).
 
kwired said:
Actually he is right in that there is voltage leaking to ground elsewhere. What both of you have so far failed at is figuring out where.

Exactly what wire were you touching back to the ground bar? Main EGC feeding the tub or the EGC of a component in the tub, or something else altogether.

Make sure you have no neutral to ground faults anywhere.
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I disconnected the EGC feeding the tub. Touching the EGC back to the ground bar on the tub with the motor running trips the breaker.

Thank you
 
growler said:
Did you check to see if the motor winding could be shorted to ground? I know it's a new motor but it is possible to get a bad one, at least I guess it is ( they are probably made in China).
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I have not checked the motor yet. Going out there today.
 
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