[RFI] Troubleshooting AFCI Tripping Due To Amateur Transmissions

[Gary Mayfield]

I had this issue at a previous house.  The old ones didn't trip and the new ones did.  We moved them around, but only the same devices tripped regardless of location.  We tore a couple apart and found the old ones had a capacitor from the hot to the neutral.  The new ones did not (probably saved a penny).  We added a ceramic disk capacitor with a more than high enough voltage rating to the new ones and the problem was solved. This is my experience.  I am not making a recommendation -- What you do is your business.  AC wiring can be dangerous.  Always use caution! Your mileage may vary. 73,Joe kk0sd  
 > Date: Thu, 3 Jan 2013 15:15:53 -0500
> From: jeff at mossycup.com
> To: rfi at contesting.com
> Subject: [RFI] Troubleshooting AFCI Tripping Due To Amateur Transmissions
> 
> A friend of a family member is experiencing an apparent RFI issue which is
> causing his code required AFCI outlets to trip, apparently due to his
> neighbors amateur transmissions.  This is in the Southern New Hampshire
> area.  Unfortunately, unlike many of us in the amateur community (who would
> relish the opportunity to troubleshoot such an interesting RFI issue) the
> operator seems unwilling to provide even a basic level of assistance.  To
> clarify, this is a situation where a licensee is apparently causing
> interference to a Part 15 AFCI in his neighbors house.  While the licensee
> may not be under any legal obligation to help troubleshoot the RFI issue,
> I'm hoping we can come up with a solution for the neighbor.  The neighbor
> has apparently spent hundreds of dollars in material and labor to have an
> electrician attempt to remedy the problem without success.  Several brands
> of AFCIs have been tried with no improvement.  The licensee has been
> unwilling to provide even basic assistance such as what bands he operates
> on, what power levels he uses, or what times he operates.  I'm looking for
> suggestions on how to reduce the RFI which the neighbor's AFCIs are
> experiencing which will hopefully eliminate the erroneous AFCI trips.
> 
> The little information we know about the licensee is that his antenna
> systems are wire only.  There appear to be no HF/VHF beams or highly
> directional antennas on the property.  I have not seen the antenna systems
> myself and these are only third party observations.  In addition to being a
> licensed amateur, the operator is apparently an RF engineer as well.  With
> this in mind, it's likely the licensee is operating on HF of MF, possibly
> QRO.
> 
> The only suggestion I've been able to come up with on my own was to build a
> choke by running the romex wire leading to the neighbor's AFCIs through a
> large toroid of the appropriate material.  This would simply be an attempt
> to prevent any induced MF/HF current on the electrical system from reaching
> the AFCI while allowing the 60Hz AC current to pass through unhindered.  Of
> course, we aren't sure what frequency the licensee is operating on so we
> don't know what material to select.  Our assumption that this is MF/HF
> interference may not even be correct -- the licensee may be operating on
> VHF+.  Is this choke idea an appropriate path to follow or should I suggest
> something else entirely?  Alternatively, are there any manufacturers of RF
> hardened AFCIs?
> 
> 73,
> 
> -Jeff
> W7WWA
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