Can someone recommend a leakage tester?

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Todd0x1

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I need to be able to measure ground fault leakage in various 120v 15a plug in appliances under operating conditions. I tried searching and couldn't really find what I am looking for. I need something that I can plug into a receptacle, then plug the appliance into this device and have it tell me the leakage current.

We do alot of portable power and I keep having event rental companies show up with defective appliances which trip the GFI and of course they blame the power not the appliance "it worked ok in our shop we tested it before it went out" so I want to be able to prove what is causing the GFI to trip.

If there's not a portable instrument I am also open to a panel mount instrument I can stick in a box. Is there some sort of ultra sensitive CT and panel meter I can pass the H+N through to get the leakage current measurement?
 
"It worked in the shop."
"Gee, it's never done that before."
"It was fine at the last show."
"Maybe you have dirty power."
"Have you tried powering off and back on again?"
"Probably a grounding problem."

There's a whole pile of these :ROFLMAO: .
 
zbang said:
"It worked in the shop."
"Gee, it's never done that before."
"It was fine at the last show."
"Maybe you have dirty power."
"Have you tried powering off and back on again?"
"Probably a grounding problem."

There's a whole pile of these :ROFLMAO: .
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Oh man you have no idea. One of the better ones I saw was this last weekend. A convection oven that electrically worked, fan running and everything, but there was no heat. Likely bad igniter, couldn't hear the buzz on this one like the other working unit had. Two guys from the company that supplied the broken oven spent quite a while plugging it into all different receptacles and switching out full propane tanks, unable to comprehend why it still wasn't working since they exhausted every troubleshooting skill they had.
 
I am not sure what the leakage tester would tell you.

Just plug the thing into a GFCI. If it trips, the leakage exceeded 6 mA. That's all you need to know. And a GFCI outlet is cheap.

I would get myself a box and install a GFCI in it and a plug for connecting to a standard outlet.
 
I have a Fluke. About 15 years old and about $700 (they are not cheap). With that said, I love it. Mostly it is a way to visibly show the customer that it is the specific item that is plugged in causing the issue (and how much leakage) and not the GFCI or the building wiring that is the problem. I have a short 6' extension cord where I have separated the hot/neutral conductors from the EGC so I can clamp just the H/N. I then attached the equipment to a non-GFCI receptacle and show the reading. You can also watch it change over time. I've found that heating elements tend to increase leakage as they heat up (example was an electric grill).

Mark
 
I think I found my solution. I realized there's probably something in the automation world to monitor ground fault current. I found some ground fault relays which read 0-100ma and output 4-20ma. For the cost of the fluke I can get one of these and throw it in a box with a little PLC and HMI and get datalogging.
 

I was going to recommend the Fluke 369 FC Leakage Current Clamp Meter - but of course that is expensive. Would you please share the part number of the GF relay you have found? Sounds like a nice alternative.​

​

If I were in the business of diagnosing GFCI trips I would go with the Fluke. For myself, with only a rare need, I converted the sensing coil from a GFCI receptacle into a makeshift GFCI leakage current device. A power supply, and a few op-amps condition the signal, that output is then read with a standard DVM. Pretty crude, and not pretty but got the job done.
I originally used it to diagnose my father in laws Christmas light tripping's. Could watch the leakage current start out low and slowly climb until the trip occurred.
 
ELA said:

I was going to recommend the Fluke 369 FC Leakage Current Clamp Meter - but of course that is expensive. Would you please share the part number of the GF relay you have found? Sounds like a nice alternative.​

​

If I were in the business of diagnosing GFCI trips I would go with the Fluke. For myself, with only a rare need, I converted the sensing coil from a GFCI receptacle into a makeshift GFCI leakage current device. A power supply, and a few op-amps condition the signal, that output is then read with a standard DVM. Pretty crude, and not pretty but got the job done.
I originally used it to diagnose my father in laws Christmas light tripping's. Could watch the leakage current start out low and slowly climb until the trip occurred.
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Here's the GF sensor https://www.nktechnologies.com/ground-fault-relays/agt-ground-fault-indicator/

I would buy the fluke, but what I really want is something that I can leave unattended plugged between the receptacle and appliance to catch random GFI trips and be able to capture the GF current at the time of the trip. I'll have to put a little more thought into this realized I need to include battery power to keep the electronics alive after the GFI trips.
 
Thanks for sharing Todd0x1,
I like your idea of logging data. Who wants to sit around watching the screen waiting for a tip :)

One of the many downfalls of my makeshift monitor was minimal tolerance for over currents. It was tuned to best resolution at 0 -10ma.

What are your thoughts on expected over currents and also the need to log data after a trip has occurred? Or is your concern memory storage?
Hopefully your PLC has non-volatile memory?
The 0-50ma option would provide a somewhat better resolution and still provide a good margin for over currents?
 
A ground fault is due to an insulation problem, so why not use an insulation tester? See, in the given scenario, the fault is explained after the event, not predicted before the event. The blame can still be put on the GFIC tripping device, not the appliance. And yes, using a ground fault meter could be used instead - if - you can get to a non-GFIC receptacle. Cheap meggers cost less than $100. In this scenario, the megger can be put to an appliance that does not trip a GFIC and then to the one that does to prove the point. You could even make up leads permanently attached to a female plug.
 
The basics of a GFCI is to run the protected conductors through a CT, if all the current coming in equals all the current going out the CT has no output.

You should be able to do the same thing - make your own CT that has all the protected conductors passing through it and monitor the output.

Since you are trying to catch just a few mA, make multiple turns of the monitored conductors to multiply the output accordingly and you won't necessarily need as much precision at low level from your meter
 
Just admit it, you put the wrong sized breaker in and it gave it too many amps. It worked fine before you burned it out
 
Joethemechanic said:
Just admit it, you put the wrong sized breaker in and it gave it too many amps. It worked fine before you burned it out
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lol. I had another job where I was asked for a 5-15 receptacle with a 30A breaker because the food vendor had an appliance from Japan that was 2400w resistive at 100v, with a 5-15 plug on it.
 
TwoBlocked said:
A ground fault is due to an insulation problem, so why not use an insulation tester? See, in the given scenario, the fault is explained after the event, not predicted before the event. The blame can still be put on the GFIC tripping device, not the appliance. And yes, using a ground fault meter could be used instead - if - you can get to a non-GFIC receptacle. Cheap meggers cost less than $100. In this scenario, the megger can be put to an appliance that does not trip a GFIC and then to the one that does to prove the point. You could even make up leads permanently attached to a female plug.
Click to expand...

Don't want to megger an appliance and potentiall damage electronics in it. The faults come and go, for example in a motor that cycles, or in heating elements that don't fault until theyre hot. Need something inline that can stay there and monitor the appliance's GF current.
 
Todd0x1 said:
Don't want to megger an appliance and potentiall damage electronics in it. The faults come and go, for example in a motor that cycles, or in heating elements that don't fault until theyre hot. Need something inline that can stay there and monitor the appliance's GF current.
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You can disconnect the electronics or disconnect the heating element and only meg the components you are comfortable testing in this way. The element that doesn't fault until it is hot still may fail when subjected to the higher test voltage of a megger.
 
TwoBlocked said:
Am trying to think of what could be damaged by putting current limited DC voltage to the power cord of an AC appliance.
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Me too, other than something that is already damaged therefore the leakage.

Also don't start off with applying 1000V test to something that operates at 120 volts.

Those control boards with the electronics on them typically operate from a lesser separately derived voltage, a hot to ground test won't put current through the control transformer and therefore won't put any voltage on the separately derived controls. If not cord and plug connected and you test hot to ground then you can get a feed back loop through the system bonding and send your test volts through the control transformer - this one reason why you need to isolate permanently wired items before testing.
 
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TwoBlocked said:
Am trying to think of what could be damaged by putting current limited DC voltage to the power cord of an AC appliance.
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alot of stuff these days has a switching power supply connected directly to the mains input. Putting 1000vdc to that is not ideal
 
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