Charging trips GFCI on my hot tub?

I have a Juicebox 40 Pro on a dedicated 50A circuit, and a hot tub on another dedicated 50A circuit.

Ever since I started using the Juicebox (1month ago), I would randomly find the hot tub turned off, with the GFCI tripped. This happens every few days, so it is hard to troubleshoot if there is a defective component in the hot tub, or if it is external.

My current hunch is that when the Leaf charging starts up, the hot tub experiences a drop which the circuitry doesn't like. I could test it this weekend by plugging/unplugging the car while watching the hot tub. If that is the case, is there anything I could do to even out this drop, at either the Juicebox or hot tub side - some sort of capacitor?

GFCI only protects from electrocution when current is detected between the neutral wire (and/or ground) so it doesn't have any ability to detect low voltage. GFCI on a hot tube might mean something else different is the issue. I can't imagine two separate circuits affecting each other like that unless there is some unknown wiring issue. Something either an electrician or friend with electronics background should investigate.

How old and what size is your main electrical service panel and drop? You may need to get it fully inspected, including a check of all the connections, proper grounding, and correct neutral/ground bonding at the main feed point. Have the wiring for both the hot tub and the EVSE checked.

There is a possibility that you have a device randomly putting juice on the ground causing the GFCI to trip. It could also just be coincidental timing, and the GFCI or a hot tub component needs replaced.

As has been said, GFCI units do nod check for voltage. Make sure the two sets of wires are separated. My guess is that the relay glitch is getting into the hot tub. Another possibility is that the JuiceBox is loading the buss's causing one to be lower than the other. This could be a bad main breaker or a power company problem.

Even though you have a high power JuiceBox the car charger sets the current. For a current Leaf with an enhanced charger the Leaf will draw its 27.5A and it will ignore the rest. Older cars only draw 16A.

28A should not be enough to unbalance the buss bars without some sort of problem.

Could GFCIs be impacted by noise? I've heard that the Juicebox can not pass UL testing because it's power supply is emitting too much noise.

I'd trying switching to the level 1 EVSE and see if your GFCI still trips. If it does then I'd try without any EV charging. Obviously this is going to take time to test and will be an interesting imconvinience but have to rule out it just being a coincidence.

FWIW my AFCI breakers were tripping randomly as the result of power line communications, though AFCI is more complicated than GFCI.

QueenBee said:

Could GFCIs be impacted by noise? I've heard that the Juicebox can not pass UL testing because it's power supply is emitting too much noise.

Click to expand...

That can't be true because UL doesn't test for electrical noise. UL tests for safety (like thermal testing, fault conditions, electrocution & fire hazards, etc... all depends on the standard being tested). On the other hand, they may not be able to pass FCC testing (and CE testing for the EU), which are two agencies concerned with EMI. That being said... it's not legal to sell commercial products that don't meet those requirements (though that's only enforced by someone bringing challenge to it).

Following a good once-over of the wiring and depending upon the age of the panel and breakers, I'd replace the GFCI breaker. Sometimes old breakers get finicky. Plus if we were to (however ineptly) chalk the issue off to some random and inexplicable noise, there's also a chance that a random breaker swap with different GFCI construction will also ameliorate it.

GFCIs are inherently very sensitive, but they're looking for difference in current between the neutral and hot that would indicate current is somehow leaving the circuit. According to the blessed stackoverflow, problems like you're seeing are almost always due to incorrect wiring or faulty GFCI device.

I wouldn't use a capacitor -- unfortunately we're in AC land, and a capacitor presents a reactive load on the circuit as the voltage changes which induces currents that don't do useful work (and in some cases you can get billed for the reactive power "used").

Also note that an EVSE is _basically_ a glorified switch, nothing ridiculously fancy.

iluvmacs said:

QueenBee said:

Could GFCIs be impacted by noise? I've heard that the Juicebox can not pass UL testing because it's power supply is emitting too much noise.

Click to expand...

That can't be true because UL doesn't test for electrical noise. UL tests for safety (like thermal testing, fault conditions, electrocution & fire hazards, etc... all depends on the standard being tested). On the other hand, they may not be able to pass FCC testing (and CE testing for the EU), which are two agencies concerned with EMI. That being said... it's not legal to sell commercial products that don't meet those requirements (though that's only enforced by someone bringing challenge to it).

Click to expand...

Does a UL listing require passing FCC testing?

QueenBee said:

iluvmacs said:

QueenBee said:

Could GFCIs be impacted by noise? I've heard that the Juicebox can not pass UL testing because it's power supply is emitting too much noise.

Click to expand...

That can't be true because UL doesn't test for electrical noise. UL tests for safety (like thermal testing, fault conditions, electrocution & fire hazards, etc... all depends on the standard being tested). On the other hand, they may not be able to pass FCC testing (and CE testing for the EU), which are two agencies concerned with EMI. That being said... it's not legal to sell commercial products that don't meet those requirements (though that's only enforced by someone bringing challenge to it).

Click to expand...

Does a UL listing require passing FCC testing?

Click to expand...

No, they are completely unrelated.

UL - does the device have a tendency to catch fire spontaneously and burn down your house

FCC - does it cause your cell phone to glitch out (typically other devices)

Intertek has a neat summary outlining what they test charging equipment for. FCC Part 15 and Part 18 verification is listed. Another thing to keep in mind, GFCI circuitry and pilot communication performance is subject to noise injection testing. If the device itself produces electromagnetic noise this could lead to test failures. Difficult to second-guess, but there could be more than meets the eye.