Cell Phone Charger trips GFI

[BBF]

So I installed two new countertop outlets at a customers house. New 20A circuit, GFI with one outlet on the load side. Before leaving I tested both outlets with my tester then with a drill. Worked great on both. Now the custmer wants me to come and fix it becasue the GFI trips when he plugs in his cell phone charger. I said it must be the charger, try something else in the outlet. Everything else he trys works great. Still he insists that I come back and fix the problem. I feel the charger is the culprit but how do I test this or explain this to him? I don't want to go back out there when there is really nothing I can do. What are my options here?

 

[Dennis Alwon]

I had the same issue in my house. Never tripped the gfci in the kitchen until my brother visited and plugged his cell phone charger in. My wife and I have the same exact charger and they did not trip the gfci.

I would tell them to plug it in somewhere else or try another brand. I was using P&S and the charger was a LG-DLC100

 

[growler]

Everything else he trys works great. Still he insists that I come back and fix the problem. I feel the charger is the culprit but how do I test this or explain this to him? I don't want to go back out there when there is really nothing I can do. What are my options here?

It's the cell phone charger. when everything else works and one item causes a GFCI to trip then the item in question has a problem.

Just explain to the customer how much you will be charging for this service call to include travel or how cheap it would be for him to buy a new charger or how easy it would be for him to plug the charger in some other place.

 

[EV607797]

While I'm in agreement, I just don't see how a cell phone charger could cause it to trip. I've never seen a charger with a ground pin, so how could there be any leakage to cause an imbalance? :?

 

[growler]

Before leaving I tested both outlets with my tester then with a drill. Worked great on both. Now the custmer wants me to come and fix it becasue the GFI trips when he plugs in his cell phone charger.

I had the same problem with a customer that lives way out in the country about 12 years ago.

Installed new countertop receptacles. GFCI starts tripping when he uses the microwave and nothing else. Drive all the way out there at the end of the day to check it out. Try other appliances, refrigerator, toaster, blender and even get out a big drill from the truck and the GFCI doesn't trip except when tested and then it works fine.

After about an hour of dealing with this dork and his wife tells me he has spilled a bowl of water in the microwave and that before that it was also working fine. Then I explain to the guy that a new microwave cost less than a service call. He didn't like it but I have done lots of work for him since then.

 

[cowboyjwc]

While I'm in agreement, I just don't see how a cell phone charger could cause it to trip. I've never seen a charger with a ground pin, so how could there be any leakage to cause an imbalance? :?

GFCI's don't use the grounding conductor, they use the grounded conductor.

 

[EV607797]

GFCI's don't use the grounding conductor, they use the grounded conductor.

Yeah, I know, but where is the leakage going? A GFI measures the current on each current-carrying conductor and if these aren't perfectly balanced, it senses leakage and trips. A cell phone charger, even if it is plugged into a phone still doesn't provide any kind of path for leakage to ground. Surely it can't be leaking into the air.

 

[drspec]

I had an issue with my old cell phone charger when it was plugged into the gfci receptacle itself. When it was plugged into a regular duplex fed off of the gfci it didn't trip. Now I have my bluetooth and tablet plugged into that same gfci and never had a problem.

 

[Dennis Alwon]

Yeah, I know, but where is the leakage going? A GFI measures the current on each current-carrying conductor and if these aren't perfectly balanced, it senses leakage and trips. A cell phone charger, even if it is plugged into a phone still doesn't provide any kind of path for leakage to ground. Surely it can't be leaking into the air.

I don't understand either but there is something in there causing an issue

 

[jim dungar]

Yeah, I know, but where is the leakage going?... Surely it can't be leaking into the air.

Maybe it is not leakage, but it is likely still through the air.

It is probable that the subject cell phone charger is emitting some type of EMI that interacts with the sensing circuit of the GFCI.

Recently. there was a thread that went into detail about issues with a fire fighter's radio and GFCIs.

 

[ELA]

It is conducted EMI from the charger. You could install an EMI filter between the charger and the GFCI to demonstrate that.

As was discussed in the other thread mentioned, a severe enough EMI level will upset any electronic device.
EMI will often upset a device in a mode outside of the devices normal sensing method.

As electricians the tendency may be to think in terms of 60 hz only. EMI is a broad range of frequencies that can take alternate paths through a device from those that 60 hz is normally intended to follow.

In the case of the GFCI I recently disassembled a unit to make an inexpensive differential current meter for my use. In that effort I tested the sensing coil and found that the coil actually has a stronger response to higher frequencies that it does at 60hz.

Items like a charger often emit higher frequencies and when they seek a path back to their source they may take different paths along each of the two conductors resulting in a differential current that trips the device.
Or in some cases the EMI may bypass the sensing coil all together and directly upset the trip circuit.

 

[EV607797]

I swear that I learn something new every day on this forum. :thumbsup:

 

[GoldDigger]

Yeah, I know, but where is the leakage going? A GFI measures the current on each current-carrying conductor and if these aren't perfectly balanced, it senses leakage and trips. A cell phone charger, even if it is plugged into a phone still doesn't provide any kind of path for leakage to ground. Surely it can't be leaking into the air.

To sum up some of the other comments and pull it together:

Think non-linear, high current loads. (A cell phone charger could be driving as much as 2A DC at around 5 volts.) The spikes on the square edges generate EMI and also can high frequency harmonics which can capacitively couple to air, counter, etc. much better than 60 Hz would. So it could be current imbalance at high frequencies or just radiated or conducted interference which is affecting the electronics of the GFCI without causing an actual current imbalance.

 

[cowboyjwc]

I swear that I learn something new every day on this forum. :thumbsup:

I know, right? I was gonna guess goblins.:happyno:

 

[ceb58]

To sum up some of the other comments and pull it together:

Think non-linear, high current loads. (A cell phone charger could be driving as much as 2A DC at around 5 volts.) The spikes on the square edges generate EMI and also can high frequency harmonics which can capacitively couple to air, counter, etc. much better than 60 Hz would. So it could be current imbalance at high frequencies or just radiated or conducted interference which is affecting the electronics of the GFCI without causing an actual current imbalance.

#1- Print out the above quote. #2- drive to customers house. #3 Give the customer the above printed quote. #4 Smash charger with hammer. #5 Hand customer bill for service call. #6 Leave and change phone number.

 

[GoldDigger]

I know, right? I was gonna guess goblins.:happyno:

You should know better than that. Odd electrical behavior is always the result of gremlins, not goblins.
Goblins have, however, been known to cause heating and plumbing problems.

 

[cowboyjwc]

You should know better than that. Odd electrical behavior is always the result of gremlins, not goblins.
Goblins have, however, been known to cause heating and plumbing problems.

EV607797 was right, you do learn something every day.

That and I couldn't remember the word gremlin. :happyno:

 

[hurk27]

If they are plugging it into the GFCI receptacle, I had a case where the customer was saying the wall wort for his cordless phone would trip the GFCI every time he plugged it in, I went there and plugged it in and it was fine, after a few times, I had him plug it in, and presto, it tripped, and I saw exactly what was causing it, his finger hitting the test button:roll:

 

[K8MHZ]

If they are plugging it into the GFCI receptacle, I had a case where the customer was saying the wall wort for his cordless phone would trip the GFCI every time he plugged it in, I went there and plugged it in and it was fine, after a few times, I had him plug it in, and presto, it tripped, and I saw exactly what was causing it, his finger hitting the test button:roll:

I have a pressure washer that, when plugged into the top receptacle of a duplex GFCI, it's own cord mounted GFCI will push the test receptacle of the wall mounted GFCI.

 

[steve66]

I'm starting to sound like a broken record, but did anyone try replacing the GFCI receptacle?