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Discussion Starter · #1 ·
Hi Everybody,

Need some advice, have a hot tub (40A) and one of the two pumps was whining so I knew bearings were going so I replaced the two speed pump, also replaced heater element.

New pump is 4.5 A more than old.

GFCI keeps tripping but only when everything is on at once. If I activate pump 1 and both stages and heater , breaker holds. Turn those off and Activate blower, breaker holds, if I activate all at once , it trips. So my thinking is that IF there was an actual ground, when I tried these tests it would still trip when I activated whatever had the ground etc.

So I replaced GFCI with a standard breaker to test for overload, and it holds and never trips.


So.....I amp metered it and it is a 40A GFCI and total load with everything running is 38.5A. Wont trip the regular breaker but maybe GFCI is more sensitive to being near max and heats up and trips? (It takes 30sec to a minute to trip).

So I am thinking its a maxed out circuit issue, so thinking of changing pump to lower amperage.

Can anyone offer another suggestion per chance?

Really appreciate it
 

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Does the blower have a universal motor ?

One with a marginal commutator ?

The most likely scenario is that both systems are leaking -- just a tad.

Then, when combined, you are over the GFI breaker threshold.

Which is enough to drive you batty.

Did you pull an amperes drawn reading ?
 

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Did you try another gfci? If possible try a dp 50 gfci. That is usually a standard size for a hot tub but the wire must be sized accordingly
 

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Does anyone know if GFCI's will trip when closer to max than a normal breaker would? Just trying to rule that out
The gfci breaker should have the same over current protection as a standard breaker. The gfci function does not trip on overload
 

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Discussion Starter · #9 ·
Thx guys. I don't get it. Gfci doesn't trip when operating any function singularly which to me indicates there is no ground. None is metered either. Only change is higher amperage pump. But like I said, when I threw a standard 40a in it never blew so I would think if it was over limit would have popped standard one too.
Maybe gfci is very old and too sensitive. Lol. Damn tub.
 

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Thx guys. I don't get it. Gfci doesn't trip when operating any function singularly which to me indicates there is no ground.
What does the lack of ground have to do with it. A gfci will function without a ground.

The fact that each one works individually with no issues is why I suggested a new gfci since a 40 amp device may be too sensitive. As we have stated many times most tubs call for a dp 50
 

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Dennis Alwon said:
What does the lack of ground have to do with it. A gfci will function without a ground.

The fact that each one works individually with no issues is why I suggested a new gfci since a 40 amp device may be too sensitive. As we have stated many times most tubs call for a dp 50
I think he meant no ground fault in the equipment, not that there is no EGC.
 

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telsa said:
Does the blower have a universal motor ?

One with a marginal commutator ?

The most likely scenario is that both systems are leaking -- just a tad.

Then, when combined, you are over the GFI breaker threshold.

Which is enough to drive you batty.

Did you pull an amperes drawn reading ?
^ This is a real possibility.

I would probably first try a new GFCI breaker rated according to your tubs nameplate -- whether that's 40A or 50A only you will know as you haven't given the nameplate info for the tub. In this case, that's cheap and easy enough to try first.

If that doesn't do it, you may have the issue Telsa described above. Disconnect all the electronic components from the tub circuitry (including the GFCI breaker), force all the motor starters and heater contactors closed, and megger the circuit. Start with the lowest voltage available on the megger you're using, in case you missed something that needs to be disconnected.

Remember that E=I*R and a Class A GFCI trips at 4-6 mA of leakage current. That means at 250V, you need to see at least 62,500 ohms of resistance in your circuit. At 500V, you need 125,000. If your tub tests better than these values at 500V, you know you need to look elsewhere.

Another possibility is that your new pump's inrush current, on top of the near fully loaded circuit, is throwing you above your breakers trip curve.
 

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I start by ensuring your OCPD is correctly sized. At just shy of 40A FLA you may be tripping on overcurrent due to inrush.

Othwise, I agree that the GFCI could be tripping due to cumulative leakage. How hard would it be to temporarily lift the grounding and bonding and see if the GFCI holds? If you only have a single ground path, you could even put your multimeter in series and look for return current on the mA scale.
 

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38.5A on a 40A breaker is too high. Even if the old pump drew 4.5A less, at 34A you'd still be over the 80% threshold. The 2012 CEC allows a 50A breaker on #8(assuming 75 degree wire). Even if it doesn't resolve your ground fault issue you still need to change the breaker.
 

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38.5A on a 40A breaker is too high. Even if the old pump drew 4.5A less, at 34A you'd still be over the 80% threshold. The 2012 CEC allows a 50A breaker on #8(assuming 75 degree wire). Even if it doesn't resolve your ground fault issue you still need to change the breaker.
Theoretically 38.5 amps should not trip a dp 40 amp breaker. It my over time cause issues however I seriously doubt that the tub sees 38.5 amps for 3 hours

The nec allows 50 amps on #8 but not if it is NM cable which is used at 60C
 
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