# Electric fence on GFCI ?



## bkmichael65 (Mar 25, 2013)

No, the GFCI is just protecting the transformer primary


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## Kunolop (Feb 9, 2013)

Yes it would trip the GFCI, the GFCI measures the current in and out and if there is a difference of 5ma or more it trips. Even though the fault is on the secondary side, the current for the fault must come from the primary circuit and with this imbalance the GFCI trips.


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## Vintage Sounds (Oct 23, 2009)

Kunolop said:


> Yes it would trip the GFCI, the GFCI measures the current in and out and if there is a difference of 5ma or more it trips. Even though the fault is on the secondary side, the current for the fault must come from the primary circuit and with this imbalance the GFCI trips.


That doesn't make sense to me. As far as the GFCI is concerned it is seeing the same current return on the neutral as is going out on the hot. From behind a transformer how can the GFCI tell the difference between current that should be flowing under normal conditions to power a load and fault current?


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## Kunolop (Feb 9, 2013)

When I say fault, I'm meaning a ground fault. So if the electric fence has a ground fault of 1a on the 24v secondary meaning the current is going through the animal to ground and not back through the neutral. The gfci would see a difference or unbalance of .18 a in the primary circuit and trip. 1 amp is a big fault for a fence, but I used it to make the math easy. Installing a gfci on the electric fence is useless, most decent electric fences have some sort of protection built into the controller so no one or animal gets hurt.


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## frenchelectrican (Mar 15, 2007)

Vintage Sounds said:


> That doesn't make sense to me. As far as the GFCI is concerned it is seeing the same current return on the neutral as is going out on the hot. From behind a transformer how can the GFCI tell the difference between current that should be flowing under normal conditions to power a load and fault current?


All it depending on how the secondary is grounded but the GFCI will sense on primary side but not on secondary side due most electrique fencers are isolated transfomer type.

Merci,
Marc


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## big2bird (Oct 1, 2012)

If the transformer was a seperate winding secondary, it would not see a fault. If it was an autotransformer it might. (Not sure).
Me, I would put it on a regular receptacle. It's no longer a convenience receptacle, but a load like a washer or dryer. Who cares? Maybe the pig?:laughing:


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## wendon (Sep 27, 2010)

Kunolop said:


> Yes it would trip the GFCI, the GFCI measures the current in and out and if there is a difference of 5ma or more it trips. Even though the fault is on the secondary side, the current for the fault must come from the primary circuit and with this imbalance the GFCI trips.


Why doesn't the fencer I put on a GFI trip then?? The imbalance on the secondary has nothing to do with the primary side.


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## wendon (Sep 27, 2010)

big2bird said:


> If the transformer was a seperate winding secondary, it would not see a fault. If it was an autotransformer it might. (Not sure).
> Me, I would put it on a regular receptacle. It's no longer a convenience receptacle, but a load like a washer or dryer. Who cares? Maybe the pig?:laughing:


If it's in an agriculture building it has to be on a GFCI doesn't it? Not sure about CEC.


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## frenchelectrican (Mar 15, 2007)

wendon said:


> If it's in an agriculture building it has to be on a GFCI doesn't it? Not sure about CEC.


I am pretty sure they are on simauir page as NEC is on.

I know for a fact our NF ( French Nomes aka French Electrique code ) is on almost excat same page as your guys on it have to be on RCD ( GFCI )

Merci,
Marc


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## Kunolop (Feb 9, 2013)

big2bird said:


> If the transformer was a seperate winding secondary, it would not see a fault. If it was an autotransformer it might. (Not sure).
> Me, I would put it on a regular receptacle. It's no longer a convenience receptacle, but a load like a washer or dryer. Who cares? Maybe the pig?:laughing:


Yeah thinking back when I saw a problem like this I seem to remember a autotransformer and we bought a different transformer and it worked fine. And yes the gfci would not see the fault current on an isolated transformer, my bad. I still wouldn't install it in a Gfci though. And I hate workin for farmers.


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## Jlarson (Jun 28, 2009)

We put them on GFCI's all the time.


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## bobelectric (Feb 24, 2007)

If that fence is only 24volts, then it isn't like the fences I touched while hunting.


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## donline (5 mo ago)

I've had an electric fence on a GFI for nearly 20 years to keep the deer from eating our flower beds. It is on a dusk to dawn timer, and has worked well until recently. Once every few days the ground fault trips. I can see nothing different in the fence, like the hot going directly to ground. Where should I look?
thanks
denny


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## Almost Retired (Sep 14, 2021)

donline said:


> I've had an electric fence on a GFI for nearly 20 years to keep the deer from eating our flower beds. It is on a dusk to dawn timer, and has worked well until recently. Once every few days the ground fault trips. I can see nothing different in the fence, like the hot going directly to ground. Where should I look?
> thanks
> denny


if the charger is 20 yrs old .... look for a new charger, it is leaking to ground and is a shock hazard


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## donline (5 mo ago)

Charger is only a few years old, but figured that is a good place to start. What seems weird is that it sometimes pops as soon as it is reset, and sometimes stays on for w week or more. ~denny


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## backstay (Feb 3, 2011)

I’d go to the GFCI first. It’s cheaper than a fencer.


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## donline (5 mo ago)

backstay said:


> I’d go to the GFCI first. It’s cheaper than a fencer.


Done that!


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## backstay (Feb 3, 2011)

Fencer


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## emtnut (Mar 1, 2015)

Any signs of water getting in the GFCI recept or the charger unit ?


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## just the cowboy (Sep 4, 2013)

By this time of year the fence has more than likely done its job of teaching the deer to stay away. Try leaving it unplugged for awhile and see if it trips. If no after a time ( week or so) plug it back in and see if it trips.


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## LGLS (Nov 10, 2007)

donline said:


> Charger is only a few years old, but figured that is a good place to start. What seems weird is that it sometimes pops as soon as it is reset, and sometimes stays on for w week or more. ~denny


When electrical parts or components begin to fail, they do not always go from “perfectly fine” directly into “nuclear meltdown/totally shot”mode. Things degrade, And may seem perfectly fine one second, and totally broke in the next, and then back again.

By the way, incidentally, if your electric fence powerpack is located indoors, there’s no need to GFCI protect it. The high voltage low amperage current on the fence only works when it actually does ground fault. That’s the whole point.


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## donline (5 mo ago)

emtnut said:


> Any signs of water getting in the GFCI recept or the charger unit ?


Possibly charger as it is outside. Would think they r waterproof given they r usually mounted outside.


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## emtnut (Mar 1, 2015)

They usually are waterproof, until they aren't anymore 🤣 

How is this fed from GFCI to outside ? Could be a GF in that cable.

Realy, you should be at www.diychatroom.com for your questions, this forum in meant for electrical pros only.


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## JRaef (Mar 23, 2009)

You likely have some kind of moisture issue with the charger or timer, either a sprinkler or something getting water inside or internal condensation causing tracking. If it’s recently installed, there was probably something missed in the installation. You should call an electrician.

I’m not a moderator here but DIY posts are not allowed so this thread will likely be closed once a mod sees it.


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## donline (5 mo ago)

emtnut said:


> They usually are waterproof, until they aren't anymore 🤣
> 
> How is this fed from GFCI to outside ? Could be a GF in that cable.
> 
> Realy, you should be at www.diychatroom.com for your questions, this forum in meant for electrical pros only.


PVC conduit threw garage wall to a male plug that goes into a GFI in the garage.


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## donline (5 mo ago)

not a GF in the cable, it is running a 414 watt pump 24/7


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## backstay (Feb 3, 2011)

donline said:


> PVC conduit threw garage wall to a male plug that goes into a GFI in the garage.


He must be an electrician.


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## Kevin (Feb 14, 2017)

@donline 

Thanks for posting on ElectricianTalk.com. However, working with electricity and electrical systems can be unsafe if not done by a professional licensed electrician. The moderators of this site would like to advise you to contact a professional electrician in your area.


If you are permitted by law in your area to do your own electrical work, please sign up at our sister site, www.DIYChatroom.com where many of our professionals are also members and are looking forward to assist you with your needs.


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We apologize for any inconvenience that this may have caused. This thread has been closed. 

I am also closing this thread because it's nearly 10 years old.


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