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Author Topic: RFI-proof GFCI breaker brand?  (Read 10476 times)
K4IQT
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« on: May 05, 2010, 01:00:40 PM »

At our new QTH, I am going to have to replace all the GE GFCI breakers in our 200A panel with some better brand.  Does anyone have any direct experience with other brands that are currently on the market???

In this new house all breakers serving baths, bedrooms, hallways, living room, kitchen, basement outlets are 20A GFCI, as required by local city building code.  The electrician installed a GE panel with GE breakers throughout, and frankly the GE GFCI breakers are little RFI disasters.  I've never had to use GFCI panel breakers before and would stick with GFCI outlets instead, given the choice (it's easy and fairly cheap to find units that won't trip with RF in the vicinity).

I first discovered this when I could not transmit more than about 50 watts output on HF without tripping one or more breakers.  Mind you, this is with an nonreactive SWR of less than 2:1 on 40M into my G5RV (equipped with coaxial choke at the end of the matching section, of course, and minimum of 40 feet from breaker panel).  The same thing occurs when using my 6BTV, also with a coax choke at its base, when the SWR is over 2:1 or so.  And the 6BTV is about 70 feet from the breaker panel.  And I am using a decent antenna tuner to provide a very good match to the rigs.  There is also a pretty good RF ground in the shack, about ten feet of 10AWG to a single copperweld ground rod in damp topsoil fill. 

Transmitting into a dummy load or anything with under 1.5:1 SWR works just fine.  If I am running a full 100W output the breaker serving the neighboring bedroom also trips.   So, I ran an extension cord from the laundry room, which has a standard breaker serving it, and it worked just fine ... until I had my desktop computer at the radio desk turned on and tried transmitting CW at 100 watts out, SWR 1.8:1, 2 ohms reactive per my MFJ-259B.  Then the GFCI breakers in both bedrooms tripped.  I know that my SWR is not where it ought to be, but with a G5RV you are a bit frequency-limited at an SWR under 1.5:1.
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AA4HA
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« Reply #1 on: May 05, 2010, 03:27:25 PM »

If you are comfortable in the circuit box you can grab a fistful of ferrite cores (type 43) and for each individual hot lead, loop them through the ferrite several times before reattaching the hot wire. With any luck you can suppress the RFI to the point where the breaker does not roll over and cry.

I went that route and have not had a nuisance trip yet. Then again I also had revamped my grounding and bonding system at the same time and it is hard to say what fixed the problem.

It is difficult to find GFCI breakers of different makes. I have a Siemens distribution panel and all of the GFCI breakers I have in there are Siemens branded.

GE, Square D, Siemens, etc.. all use a different stab attachment and hooking ear in their distribution panels.

Tisha Hayes, AA4HA
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
K4IQT
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« Reply #2 on: May 06, 2010, 04:46:32 AM »

Tisha, thanks for the info and tip.  I took a look at the panel but the electrician has run the wiring with very little slack, unfortunately not enough to allow a couple of turns through ferrite cores.

If I cannot replace the breakers themselves, I will probably look at redoing my RF ground at the shack.  A single ground rod is not really a very good ground source, so either multiple rods or a ground screen may be best.  I'll have to read up on that - my RCDD training back in the '90's was good for electrical supply and lightning grounding but really never touched on RF grounding.  Also, strategically-placed ferrites at the load end may help reduce the RF exposure in the shack itself.
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AA4PB
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« Reply #3 on: May 06, 2010, 05:53:19 AM »

My guess is that you probably have RF following the coax shield back into the house. It seems unlikely that 100W from an antenna 40 or more feet away from the house would trip breakers by direct radiation from the antenna.

How are your grounds connected? If you have a poor RF ground on the radio and that ground is bonded back to the electrical system ground as NEC requires then you might have a pathway for RF into the electical panel.
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WB4BYQ
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« Reply #4 on: May 06, 2010, 06:01:34 AM »

I would look at just using standard breakers at the panel, and installing some plug GFI were necessary.  

I am not sure if the s.w.r. is the problem or just the rf from the from transmitting is getting into the house wiring.  maybe ferrite snapons on the ground wire will do the trick
since gfi's look at the ground loop current.

richard
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K4IQT
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« Reply #5 on: May 06, 2010, 06:33:58 AM »

My guess is that you probably have RF following the coax shield back into the house. It seems unlikely that 100W from an antenna 40 or more feet away from the house would trip breakers by direct radiation from the antenna.

How are your grounds connected? If you have a poor RF ground on the radio and that ground is bonded back to the electrical system ground as NEC requires then you might have a pathway for RF into the electical panel.


I'm sure there is some RF returning via the 75 feet of RG-8X, but there is a proper coax antenna choke at the juncture of the feedline and antenna matching section.  When using the vertical, the choke is at the base of the antenna.

The grounds are connected only via the equipment chasses, and removing the RF ground connection seems to make the tripping worse.  This leads me to believe that a better RF ground should bear some good results.

In any case, it seems that GFCI tripping by RF is a pretty common problem - it's just that only new homes have GFCI's in living spaces outside of the bathrooms.  I'd love to replace the breakers with standard units, but would have to be prepared to re-install the GFCI's if we were to sell (per city code requirements).  I'd rather beat the problem, and am reasonably sure I can with sufficient grounding and RF blocking.  Alternatively I can buy a remote tuner and keep the SWR on the feedline always close to 1:1.  That may be the ultimate solution since no significant experimentation or code deviation would be needed.

Thanks to everyone for opinions and suggestions so far!
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WX7G
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« Reply #6 on: May 06, 2010, 09:56:34 AM »

BRYANT has RFI GFI outlets. they work. They might have what you need.
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AA4PB
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« Reply #7 on: May 06, 2010, 10:17:02 AM »

How about trying another RF choke closer to where the coax enters the house. Also ground the shields to one or more ground rods just before they enter the house. How is the coax routed to the antennas? Is it below ground or hanging up in the air? If its in the air, you might try laying it flat on the ground. If that works then you might consider burying it directly or in PVC conduit.

Everything you've said points directly to common mode RF currents flowing on the outside of the coax shield and bringing the RF into the house where it can couple into the wiring.
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K4IQT
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« Reply #8 on: May 06, 2010, 10:50:43 AM »

While the existing choke is within 10 feet of the house entrance (basement wall), there is about 60 feet of coax between there and the tuner.  This is one of the problems you get when the shack cannot be close to the feedpoint.  I also might try a bigger antenna choke (in uH).  Grounding the coax shield at that point probably would not be a good idea unless a full counterpoise is built as well - which should not be necessary on the G5RV.

The sensitivity of the breaker is such that about 10 watts into a 6:1 SWR is enough to trip it.  The match between the tuner and rig does not seem to enter into this very much, though.  Results are similar without the tuner on 80/40/20, since I have an SWR under 2:1 across each of those bands except the lower CW portions of 80 and 40.  There are a bunch of potential remedies, unfortunately excluding replacing the breakers permanently, and I will get to work on it again!
« Last Edit: May 06, 2010, 10:52:42 AM by Terry Welch » Logged
AA4PB
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« Reply #9 on: May 06, 2010, 11:32:54 AM »

Actually the SWR shouldn't affect the common mode currents directly. Probably antenna detuning is affecting both the SWR and the common mode currents. Try disconnecting the antenna and connecting a dummy load to the coax out at the antenna site and see if you can run full power without tripping a breaker. If that works then try temporarily moving the tuner to a point right near where the coax enters the house, either inside or outside.

Yes, a radial system at the entrance would provide the best RF ground, but any RF ground like two or three rods separated by 8-feet or more and tied together might help. It would also provide a good lightning ground for the antennas and it should at least help to lower the common mode currents following the coax into the house.

How is your antenna coax routed inside the house? Is it running long distances parallel to or bundled with AC power wires? You might try temporarily running some coax on the floor to keep it away from power wires to see if that helps.
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KF7CG
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« Reply #10 on: May 06, 2010, 11:41:31 AM »

Here is some good news for you.

With the correct models of GE Panel you can select either Seimens or GE Breakers. In one area I had to use Seimens breakers in my GE Panel because the GE breakers were not available, in another area it was Seimens that wasn't available and I had to use GE. I do tend to move about every three years (yuck!).

The GE/Seimens thing is not always a match, it depends on the box model. Square D doesn't seem to have equivalents.

Check the house grounding carefully, I find that it is often a mess. Also check the condition of the connection. I saw a note somewhere that for the first couple of years, the house ground should be inspected and tightened every six months. Believe it or not the can tend to work loose.

The longer run for the panel box breakers gives them a bigger antenna, good luck.

KF7CF
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K4IQT
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« Reply #11 on: May 06, 2010, 12:10:55 PM »

Try disconnecting the antenna and connecting a dummy load to the coax out at the antenna site and see if you can run full power without tripping a breaker. If that works then try temporarily moving the tuner to a point right near where the coax enters the house, either inside or outside.
Yes, I can run full power with no problem when I put a dummy load on the feedline at the antenna, so perhaps I should be looking for a remote tuner since I'm working multiple bands.

Quote
Yes, a radial system at the entrance would provide the best RF ground, but any RF ground like two or three rods separated by 8-feet or more and tied together might help. It would also provide a good lightning ground for the antennas and it should at least help to lower the common mode currents following the coax into the house.
That is certainly doable.  I was under the impression that the RF ground should be located close to the equipment, not at the antenna.  But if it does not cause problems it is certainly worth a try.

Quote
How is your antenna coax routed inside the house? Is it running long distances parallel to or bundled with AC power wires?
In the basement ceiling the coax is routed perpendicular to all AC wiring since it comes directly across the house from back to front, and most of the AC wiring runs lengthwise since the power panel is in the opposite end of the house.

The longer run for the panel box breakers gives them a bigger antenna, good luck.
No kidding!  Although, while the G5RV is roughly parallel to most horizontal house wiring, the vertical gives me exactly the same issue, so it is most likely common mode RF entering the house wiring via the wall sockets at the shack.  I hope.

Quote
Check the house grounding carefully, I find that it is often a mess.
That is one area where we're in pretty good shape.  The AC ground is not the usual ground rod but is a 10AWG copper wire directly from the panel to a sizable ground screen beside the footer.  The only fallacy with it is its length - about 20 feet.  However, a good part of that is vertical in the inside corner of the garage and basement walls.

Thanks again!  With the info you all have provided I should be able to work my way out of this RFI mess.  It just will require work and patience.  Too bad there's no Aleve for RF aches and pains ....
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WB4BYQ
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Posts: 179




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« Reply #12 on: May 06, 2010, 01:38:06 PM »

look at radio works web page and the RFI and TVI page.

here is the link
http://www.radioworks.com/

wb4byq
richard
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K4IQT
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« Reply #13 on: May 06, 2010, 02:00:15 PM »


Thank you - good info there.  I ordered some toroids and ground strap braid - it's bound to help.
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KD6KWZ
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« Reply #14 on: May 08, 2010, 07:10:34 PM »

My $.02:

Is the wiring inside your new QTH in conduits? That provides nice RF shielding, but most new wiring is not in conduits! Hence, your power wiring can turn into antennas.

I also suspect that the hot or neutral wires are at a 1/4 wavelength (or multiple thereof) of 40M between the main box & the various power outlets. GFI's trip for an unbalanced current flow between the hot & neutral lines. So, it possible for the neutral to be a suspect as well.

Does this happen on other bands?

I would NOT add ferrite beads to any ground wires! You may need the lack of reactance there. I second using strips instead of wire for the rig ground, also to eliminate resonance issues.

Is your power line house feed come in above ground? If so, that could also be the RF entry point. Toroids on both hots there may help.

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