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Author Topic: Ground Fault plug in  (Read 5334 times)
KT4DLB
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Posts: 76




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« on: February 12, 2013, 01:42:52 PM »

I'm thinking about putting a ground fault plug in my shack where the power supply will plug in to. Would this be a good idea or not? Just wanting to be safe on all points.


73 Lamar
KK4NZO
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AA4HA
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Posts: 1482




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« Reply #1 on: February 12, 2013, 01:47:35 PM »

I have GFCI outlets on all of my radio gear. I have had to make some changes on some legacy gear that had leaky capacitors on the primary side of the power supply that was causing trickle currents down the safety ground.

That is how a GFCI works; it monitors the current through the ground pin and if it sees current flow it will trigger the GFCI to open the circuit. We are talking about currents in the low milliamps range.

A downside of GFCI protectors is they can also trigger on RF current in the ground conductor. That may point to a different problem where you have excessive RFI in the shack that is causing nuisance trips. Just be prepared for them and deal with the problems one at a time.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
KT4DLB
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Posts: 76




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« Reply #2 on: February 12, 2013, 02:07:01 PM »

Should I not go with the ground fault then? The plug in is a three plug outlet anyway.
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WB2EOD
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Posts: 219




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« Reply #3 on: February 12, 2013, 02:15:56 PM »

GFCI protection is meant for wet locations.  Kitchen, bathroom, garage, outdoors.  Assuming your shack is not subject to flooding, I wouldn't bother. Just have ordinary properly installed outlets.   
Some GFCI outlets are RF vulnerable and will in the presence of strong RF.  I have experienced this problem with the transmitter RF tripping the GFCI on another branch circuit.  Eventually I found a brand that was better than others.     

Hope this helps

73
WB2EOD
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AA4PB
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« Reply #4 on: February 12, 2013, 02:52:01 PM »

Actually, the GFCI breakers work by compairing the current on the hot and neutral wires. If they are not equal then some current must be leaking to ground somewhere and it trips.

Unless you are on a bare concrete or other "wet" location I wouldn't use GFCI breakers in the shack. You will be asking for unnecessary RFI and reliability problems.
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K4FMX
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Posts: 17




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« Reply #5 on: February 16, 2013, 02:42:39 PM »


A GFCI is always a good idea especially when you have equipment like hams have. Most have some sort of outside ground that they connect the equipment to. If a fault or leakage should get on the chassis of something and you come into contact with it and the outside ground (your antenna connection) that you are hooking up you can get zapped. It doesn't have to be a concrete floor or a wet location.
You may have the cover off working on something and come into contact with the power lead. The GFCI will trip and save you a little discomfort, maybe a lot.

And yes the GFCI looks for a difference in current between hot and neutral. No ground lead needed for them to work.

73
Gary  K4FMX


GFCI protection is meant for wet locations.  Kitchen, bathroom, garage, outdoors.  Assuming your shack is not subject to flooding, I wouldn't bother. Just have ordinary properly installed outlets.   
Some GFCI outlets are RF vulnerable and will in the presence of strong RF.  I have experienced this problem with the transmitter RF tripping the GFCI on another branch circuit.  Eventually I found a brand that was better than others.     

Hope this helps

73
WB2EOD
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AA4PB
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« Reply #6 on: February 16, 2013, 03:03:33 PM »

That's exactly why the NEC requires that your outside ground be bonded (permanently connect) to the building's electrical service ground. You don't want the possibility of a difference in voltage between the two grounds.

Remember that GFCI breakers only work if you cause current to flow in the hot lead that does not get returned through the neutral. If you are working on equipment and get your fingers between the hot and the neutral then the GFCI won't protect you. They have a rather limited application and are not an "all hazards" safety device.

The problem with GFCI breakers in the ham shack is the potential for nuisance tripping caused primarily by high levels of RF.
« Last Edit: February 16, 2013, 03:21:56 PM by AA4PB » Logged
K1CJS
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Posts: 6042




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« Reply #7 on: February 19, 2013, 02:21:57 AM »

Just a side note here, some localities are now demanding GFI breakers on ALL new construction.  If you've got problems with circuits shutting down in a new building but don't see any GFI outlets, check the circuit breaker panel.  Chances are that you'll find a panelful of GFI breakers installed, and some of those can be just as twitchy as some GFI outlets--if not more so.  73!
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AA4PB
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« Reply #8 on: February 19, 2013, 05:36:55 AM »

More and more localities are now requiring arc-fault breakers on all or some of the circuits in new construction. Those may look like GFCI breakers but they are designed to protect against intermittent (or arcing) connections that might ignite a fire rather than protecting from electrical shock like the GFCI (although some may incorporate arc-fault and GFCI into the same device).

Arc-fault will be yet another source of nuisance tripping when there are high levels of RF around.
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N3QE
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Posts: 2284




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« Reply #9 on: February 19, 2013, 06:51:16 AM »

The only thing that would set off a GFCI between the wall outlet and the DC power supply, would be a fault in the wiring DC power supply that tied the AC ground to something. If you aren't poking around inside the DC power supply or putting it in the bathroom where it'll get wet, there's almost nothing you are actually protecting with a GFCI there.

Where GFCI's do some real good, is with hand tools, appliances that have liquids in them or are used near sinks, and wet locations. In those cases... the GFCI is not there to protect the equipment, it is there to protect the human who might be touching the equipment.
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K1CJS
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Posts: 6042




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« Reply #10 on: February 19, 2013, 08:10:29 AM »

Thanks, Bob.  I knew there was yet another term for those breakers, but I couldn't come across it.  As you say, most of them are also GFCI breakers as well.  73.
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AA4HA
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Posts: 1482




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« Reply #11 on: February 19, 2013, 09:58:57 AM »

Thanks guys, you are quite correct about the hot/neutral current. I was working from memory of when I dissected a bad GFCI outlet and saw the tiny CT (current transformers) inside of the unit going to a chip.

I bought a big bag of clip on ferrites that I put on lots of outlet cords and LAN cables all over the house (it was a day long fun project inside the house on a rainy weekend). I had some random tripping problems before I did that (usually when working >500 watts) and they went away. Also there was a slightly noticeable improvement of noise levels on the lower bands (160/80). Only on a few computers did I need to take more drastic steps of ferrites on everything (speaker cords, keyboard and mouse cables, monitor cables, Ethernet cables) and in one instance I just elected to eventually replace that machine.

Inside of the breaker panel I have clip on ferrites and where I had the room I would loop a conductor for a few passes through it before where it ties into the breaker.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
W5DPK
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Posts: 12




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« Reply #12 on: March 14, 2013, 10:56:19 PM »

Don't do it.  They are a pain in the behind. With  most  any power level they will trip intermittently.

Dennis w5dpk
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