Electric fence

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paul renshaw

paul renshaw

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Cordova, Maryland
Should the ground rods and conductor supplying them on an electric fence be bonded to the system GEC? There is a structure built that has a sub panel mounted on it and also the electric fence charger equipment. The charger is plugged into a GFI fed from the panel. The sub panel is fed with four wire (1 ph 120/240) with neutral and ground split, and 2 rods for earth connection. The fence charger energizes 2 of the four strands at + and the other two are - which are also connected to earth by rods. Wouldn't there be a potential difference between the two if they are not connected (bonded)?
 
The ouput of an electric fence charger is not covered by the NEC. Follow instructions of the fence charger.

The fence operates at a high enough voltage that it is not really necessary to ground any strands of the fence. There is plenty of voltage to earth no matter what. If this is a fence for livestock they have four barefoot ground references spread out over a larger area than the two shoe covered ground references that a human has.
 
iwire said:
Where can I find this info?
Click to expand...

If there is no info, isn't that a sign that it is not covered? Question is where is the output of a fence charger covered in the NEC?

I would say the fence charger is utilization equipment and any such installation information is covered by any third party listing requirements and not directly by the NEC.

Around here the farmers and ranchers use these all the time. There is no requirement to be licensed or to apply for a permit to install one. I have never been called to install one or even troubleshoot one other than if there is no power at the 120 volt receptacle that it plugs into.
 
Three or four times a year the cable man will stop by and ask if we will turn off our system for about an hour so they can trouble shoot their little boost trany that is across the street. His equipment picks up the beat of the unit.

My fencing unit has a delta grounding system that is not bonded to the barns electrical system. It was at one time but I got tired of hearing the signal in my sound system. It also caused distortion in the surveillance cameras in the
barn.

 
What are you trying to keep in, or out? We have a three wire with the center grounded. IIRC the instructions with ours indicated the ground rods, 3 nearest the fencer, should be at least 20' from any electrical system rods.

It does not take much of a meter to see a fencers influence if they are incorrectly installed.
 
I don't believe the secondary output of the fence charger (the HV side) is connected (bonded) in any way to the input power -- should be a fully isolated transformer output.

One side of that fence HV output will be connected to earth. Best to keep that connection somewhat isolated from your house ground electrode system so as to keep annoying signals out of it. It will still couple through the earth, but best to have that additional earth resistance between the fence charger and your house ground as opposed to a solid connection.

Some fence instructions say to keep their rods 50' from other ground electrode systems, some say 20', you would probably even be fine at 10'. But the key is you want some isolation from other ground electrode systems.
 
I was able to finally locate a set of instructions, and it says to keep it independent of the GES for the buildings. This is on a fence for horses, and I had a guy at an auction tell me he used the same rods that were on his building system, and it worked fine, but I will go with the Mfg. instructions.
 
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