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new switching power supply tripping GFCI


Newb

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42 minutes ago, Newb said:

New 50 amp switching power supply tripping GFIC the minute it is turned on. ?????

Many of the switching power supplies use simple capacitive input filters. When switched on the high inrush current to charge them up can pop fuses and circuit breakers. The better power supplies have a “soft start” circuit that slowly charges the input filter capacitors over a few seconds.

If your power supply has a soft-start circuit it might not be working.

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I have tried it with a GMRS radio attached and with nothing attached.  The first time it would only trip the GFCI receptacle when keying the transmitter. I reset the GFCI and just let the power supply run with the radio on but I did not transmit. After about 2 minutes the GFCI tripped and every time I reset it, the GFCI would trip.  I unplugged the power supply and everything in the garage including the drill press worked fine.

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So if I’m understanding you correctly this is tripping a GFCI receptacle and not a GFCI breaker. That narrows down the tripping to a ground fault and not an overload of the circuit. A GFCI operates by monitoring the current on the hot side vs the neutral side. At about 5 milliamperes difference it trips due to the current not returning on the neutral. Thus the current is going somewhere else, a ground fault. (Side note, Even if the receptacle isn’t grounded it will still trip).  So it sounds like you have a ground fault in your device that you are plugging in. A GFCI breaker will also trip from over current. To much load. Another factor at play if you have a newer home is an Arc fault breaker and or receptacle. They work differently than a GFCI. This can be confused as a GFCI and some arc faults are both. Here is where it gets fun… some arc faults have been known to trip from RF. That’s a whole other rabbit hole.

Try plugging into another known GFCI circuit in your home. If it’s tripping it probably has a fault. If not you may need to have an electrician check the garage GFCI but since you mentioned everything else works in the garage my guess is it’s not the issue. 
One last thought here, @Lscott mentioned capacitive input filters on the power supply. Which could be at play. I don’t want to go down more of a rabbit hole than I already have but I would be interested in what the manufacturer of the power supply had to say regarding the tripping. 
There can be many factors involved here. Disclaimer I do recommend electrical work be done by qualified electrician. 
I hope this helps and good luck. 

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2 hours ago, Newb said:

I have tried it with a GMRS radio attached and with nothing attached.  The first time it would only trip the GFCI receptacle when keying the transmitter. I reset the GFCI and just let the power supply run with the radio on but I did not transmit. After about 2 minutes the GFCI tripped and every time I reset it, the GFCI would trip.  I unplugged the power supply and everything in the garage including the drill press worked fine.

How does it work with the radio completely disconnected from the power supply?

How are you grounding the radio, or are you leaving it ungrounded?

Same for the antenna.

Finally, what does the power supply instruction manual say about being plugged into a GFCI receptacle? I’ll attach a screenshot from the part of a Samlex manual that addresses this:

 

 

C783E3A9-5696-4A78-ABFD-1ABF133384B2.png

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1 hour ago, Sshannon said:

Finally, what does the power supply instruction manual say about being plugged into a GFCI receptacle? I’ll attach a screenshot from the part of a Samlex manual that addresses this:

Great find @Sshannon, I was wondering what the manufacturer might have regarding this. 

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A little additional info on the RF factor, here in California when PG&E first went to remote reading meters the frequency they used didn't get along with GFCI breakers made by Zinsco and were causing breakers to trip in some homes. Similar issues occurred with some of the early arc fault breakers.

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