GFCI breakers vs 2-way radios

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dfiler

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Does anyone else have experience with GFI breakers being tripped by 2-way radios?

I ran across a Murray panel in which nearly all of GFCI breakers would trip if a Motorolla walky-talky was used within a few feet. Needless to say it made the work slower going.
 
It must be fairly common, as the update to UL943 GFCI product standard, effective July 2006, added improved resistance to radio interference/
 
I always managed to make a Motorola Business radio trip GFI breakers.

Of course, hardly anyone uses those radios any more. I once found a list of the frequencies they used, but have since lost it.
 
dfiler said:
Does anyone else have experience with GFI breakers being tripped by 2-way radios?

I ran across a Murray panel in which nearly all of GFCI breakers would trip if a Motorolla walky-talky was used within a few feet. Needless to say it made the work slower going.
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Check the paperwork and see if you need a license to operate the units. License free FRS radios are power limited and should not be able to emit enough power to affect nearby devices. Higher power GMRS radios, however, do emit enough power to trip the devices and require an FCC license to legally operate, but are sold openly and marketed as for use in any situation and does little to stress the FCC license requirement.

Check your paperwork. In lieu of that, try channel 8 on your radio and see if there is any difference. If there is, I have just proved my point.

Bear in mind that as a user of a Part 15 device you are responsible for any damage caused by that device. If you are an unlicensed user of a Part 95 device and cause damage, you may also have to face the FCC for illegal use of a radio emitting higher power than allowed by the non-licensed allocations.
 
It is common for radios to cause upsets in all kinds of electronic equipment, GFCIs included.

Assuming you are in the "legal range" then the best practice is to keep a good distance from electronics when keying up the radio.
 
I have a background with electronics and never researched this or understood it. What gives? What is affected??? Can anyone explain in full detail?
 
76nemo said:
I have a background with electronics and never researched this or understood it. What gives? What is affected??? Can anyone explain in full detail?
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76Nemo - full detail would be difficult as it varies from product to product.

There is an standard electrical interference test called "RF common mode".
It is intended to simulate the effects of radiated electromagnetic interference (like keying up a radio).
In this test you can inject varying levels of current into conductors under test depending upon the immunity level the device must be able to withstand.
Some common levels are 3V/meter and 10V/meter. In the RF common mode test this may correlate with as much as 33 milliamps of high frequency current.

If you induce as much as 33ma of noise current into wires ( and in the case of a GFCI in an unbalanced fashion) then you can see one way a failure may occur.
 
Thank you.

Thank you.

Thank you for that ELA:smile: I have heard of the discussion before but never looked into it, nor have had it happen with me:cool:

Don't know if you don't ask, right? That wasn't that hard.

Thank you for your time!
 
Radio White Spaces

Radio White Spaces

As a side note: The up-coming switch from analog TV to digital TV will make some of the old TV and wireless microphones frequencies available for new applications. This will make some old wireless equipment obsolete! For more information on this upcoming "Radio White Spaces" change see:

http://www.sweetwater.com/feature/wireless/white-spaces.php
 
090227-1432 EST

dfiler:

I can not run a controlled experiment like ELA mentioned. However, I ran two experiments with my test Leviton GFCI.

The GFCI was fed with two wires only, but there was a ground wire in the 20" long cord to the GFCI. Two different transmitters were used. A Motorola Talkabout T5720 on channel 1 (high power 1 W). And a Kenwood TR7625 2 meter 25 W transmitter at 145 mHz.

The Motorola with its antenna in immediate contact with the GFCI input cord could not trip the GFCI.

The Kenwood in 25 W mode with a 1/4 wave antenna (about 20" long) parallel and close to the GFCI input cord could not trip the GFCI until the antenna to cord spacing was within about 1/2 to 1".

I would classify this GFCI as moderately immune to RFI.

.
 
gar said:
090227-1432 EST
I ran two experiments with my test Leviton GFCI.

The GFCI was fed with two wires only, but there was a ground wire in the 20" long cord to the GFCI. Two different transmitters were used. A Motorola Talkabout T5720 on channel 1 (high power 1 W). And a Kenwood TR7625 2 meter 25 W transmitter at 145 mHz.

The Motorola with its antenna in immediate contact with the GFCI input cord could not trip the GFCI.

The Kenwood in 25 W mode with a 1/4 wave antenna (about 20" long) parallel and close to the GFCI input cord could not trip the GFCI until the antenna to cord spacing was within about 1/2 to 1".

I would classify this GFCI as moderately immune to RFI.

.
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Nice test Gar!
I would agree that the GFCI you tested is moderately immune to the "Channel 1" and 145Mhz frequencies.

GFCI's previous lack of EMI immunity was specifically addressed in newer models.

The RF common mode test is performed by sweeping the frequency from 150Khz to 80 Mhz.
For the directly "illuminated" RF test the sweep range would be 80 Mhz to 2 GigHz.

here is some equipment for the job:
http://www.rohde-schwarz.com/www/downcent.nsf/file/1SP32_R2.pdf/$file/1SP32_R2.pdf


I used to run the RF common mode test years ago but no longer have access to such test equipment. I would find that there were "frequency nodes" were the equipment would be more or less upset.
 
090228-2213 EST

ELA:

Thanks for the reference.

I would guess your "frequency nodes" were some resonance spots in the equipment being tested, and/or the leads to them.

.
 
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