GFCI on Vending Machine

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Not necessarily the problem here, but remember that the 6ma GFCI trip is cumulative. So if the power supply has filter caps to ground that normally draw 3ma it will not trip anything. And if some intermittent event on the same circuit also draws 3ma it will not cause immediate problems. But put them both on the same circuit and when the power supply is on at the time that the intermittent event happens you get a trip.
This would never trip the GF protection in the cord, nor would it trip at home.
Try measuring the ground current on a good power supply to see how close to the edge you are.

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K8MHZ said:
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That's considerably closer than next door. (it's also considerably less energy than the typical 5-50 kW broadcasting station)

Long, long ago and far, far away, I was an electronics bench technician at a shop less than a mile away from a 50 kW AM transmitter. When servicing audio equipment, we didn't need a signal injector. A handheld probe -- not connected to anything, just handheld -- was sufficient.
 
drcampbell said:
That's considerably closer than next door. (it's also considerably less energy than the typical 5-50 kW broadcasting station)

Long, long ago and far, far away, I was an electronics bench technician at a shop less than a mile away from a 50 kW AM transmitter. When servicing audio equipment, we didn't need a signal injector. A handheld probe -- not connected to anything, just handheld -- was sufficient.
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I know we are not talking about AFCIs here, but there are instances where 100 watts over 400 feet away would trip them. I just wanted to illustrate that it doesn't take kilowatts to trip a GFCI.
 
zbang said:
Vibration? (Someone kicking the machine or running a cart into it?)
Dryer exhaust aimed at it?

Unfortunately, you probably need a trusted 3rd party on-site to check things, customers are notoriously inaccurate in reporting problems :D.
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Have you tried taking the GFI completely out of the system and just trying it without the GFI ?

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This is at a laundromat, you have several motor driven appliances there, some may have newer electronic speed controls and introduce RF possibilities. Could be inductive kick back issues from some machine(s).

I doubt there is anything wrong with the vending machine in question or the GFCI .

Is the laundromat always being used when they are trying to figure this thing out? If one can find a period when nobody is using any other machines maybe it will hold because whatever is causing the problem isn't in use at the time.
 
Figured I might as well give an update here.....

The customer took it upon himself to buy an aftermarket Leviton GFCI from Home Depot. He installed that on 11/3 and since then all has been okay. The Leviton GFCI has not tripped and the vending machine has been in full operation.

The thought here would be that there was some type of interference knocking our GFCIs out but the Leviton unit, for whatever reason, does not seem as sensitive to that interference.

Ideally, for my own knowledge, I would have liked to have isolated the vending machine from some of the other equipment on site just to see what the specific cause was. Unfortunately we won't be able to do that though. The customer is happy, so in their eyes it's case closed for them.

The customer did return all of the replacement parts that we sent them (the power supply, the full length power cord w/ in-line GFCI and the 2 replacement GFCIs) and naturally all of that equipment has been running fine in our shop for the last few days.

Definitely appreciate everyone's input on this.
 
MAC702 said:
Glad it worked out amicably! Some customers refuse to understand that a problem can be on their end when all of their stuff is currently "working."
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I think the step we took of having him bring the equipment to his home and power it up at his home really went a long way in showing him something funky was going on at the laundromat. When we couldn't get the GFCI to stay on for longer than 1 hour at the laundromat, but it stood on for 12 hours at his home, I think he realized what we were dealing with.
 
md40022 said:
I think the step we took of having him bring the equipment to his home and power it up at his home really went a long way in showing him something funky was going on at the laundromat. When we couldn't get the GFCI to stay on for longer than 1 hour at the laundromat, but it stood on for 12 hours at his home, I think he realized what we were dealing with.
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You needed some incentive for the owner to come out and get to the bottom of it. After all it sort of would be turning into a field lab for further development of your product.
 
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