installing a lightning diverter

[Runestone]

I posted on the sheep forum, but it was suggested I might get more information here

Okay...we have our electric fencing all set up, and after much trial and error, it's running perfectly. Now we want to install a Gallagher lightning diverter - especially since last summer, our house was struck by lightning. The storms up here seem to be getting more violent....

so, the instructions are horrible...I'm not sure who writes these, but they don't seem to make much sense. Can anyone give me a clear and simple explanation on how to install the diverter?

thanks so much

[secuono]

Yea, I stare at those and have zero clue what to do with them....


Still haven't gotten one. Our house is always being struck by lightening, at least 4-6 times a year. We knew that based on the one outlet that always died, eventually we got a new electrician who told us the grounding wasn't on it, that's why the lightening always killed everything on that plug and the breaker...

[agmantoo]

Save your money. That device is nothing more than an adjustable air gap. The word "likely" is used to describe its function. The intent of the device is to route a lightning strike that comes from a hit to the fence and route the strike to ground. Nothing will be done by the device to protect a power surge or a hit to the utility power line. Buy fence energizers that have a manufacturers warranty and divide the warranty period in months into the price of the energizer. That is you cost for having protection. Man has never been able to divert lightning satisfactorily enough to prevent damage by a significant electrical surge well enough to prevent damage.

[Harry Chickpea]

" Man has never been able to divert lightning satisfactorily enough to prevent damage by a significant electrical surge well enough to prevent damage."

Not true. A basic air gap protector and choke coil for an electric fence is a DIY project. Too late tonight to go into it and I have some support work that gets the push in the morning, but I'll to give you instructions sometime tomorrow.

[agmantoo]

I already have an adjustable air gap and I have a commercial choke along with all the proper ground rods and the appropriate wiring and hardware. I just recently replaced my Gallagher expensive charger due to a hit from the fence side. I also have grounds on the fence and I have limited the number of hot wires to 1 with my useless attempts to minimize damage to my energizers. I have both the input and the outside side of the energizer "protected" with quick blow 1 amp fuses.

Hopefully you can introduce me to a method that works. Oh yes, the power company has two of their arrestors in series at my connection to their service lines. I also have a whole house surge protector at the main power panel.
On average I lose at least 1 to 3 energizers per year to electrical damage. I was told that we are either #3 or #4 in lightning hits per year for the continental USA.

[Harry Chickpea]

The trick is in how you configure it. Lightning is not DC but multi-frequency AC. It "seeks" the path of least resistance. Resistance in this case includes minimal inductance and NO SHARP TURNS.

The diagram explains the basics. The lead from the fence to a ground might be best at a fence corner, leading down with a fairly good gauge wire - #10 or #8 copper. the spark gap wants to give a STRAIGHT shot at the ground lead. The ground rod and surrounding ground must have minimal resistance. The soil in a naturally wet place is ideal, conductivity of the soil can be increased some with salt. If the ground isn't good, it will be ignored.

Note then how the lead to the charger comes off at an extreme angle and is a smaller gauge wire. A ferrite split core can add some inductance on the high frequencies, the larger loop coil handles the lower one which typically have more current.

In a single use situation a very pointy spark gap would be ideal, since the electrons will stream off a point easily. Because of repeated strikes and high current, brass balls or other conductors capable of withstanding heat end up being better. The balls at the base of the 300' radio antenna at my dad's radio station were about 10" in diameter, and regularly held arcs during thunderstorms.

The reason for difference in wire gauge is that the high current of lightning will find little resistance in the larger gauge, and much higher resistance in the small gauge going to the charger. Since the charger electricity output is high voltage and far lower current, it can operate fine with a 16 gauge wire. If you think of the lightning as the stream of water coming out of a high pressure fire hose, and the charger electricity as the water from a 1/2 house pipe, you'll get the general idea. You don't want to even try to divert that fire hose water from where it wants to go. You want to make it straight shot easy.

[agmantoo]

Thanks for the schematic! I need a little more info if you have time. I understand the need for the minimum resistance on the earth ground. Where the word charger is printed this is the output of the fence charger hot wire if I am reading it correctly. I understand the choke and its location. I also understand the 16 gauge fine wire and I understand the low amperage and the high voltage output. What I do not understand is that in my own setup I have a fuse holder for a Littlefuse brand glass encased 1 amp fast blow fuse that is only a few thousandths in diameter wire inside. I have an air gap (homemade) that is grounded. The air gap is adjusted to a minimum space from the hot wire to ground to where the hot wire only occasionally will spark to ground through the air gap. Yet when I get a strike the fuse blows as I expect it to do but I will still get enough power to sometimes blow the output transformer of the charger apart. I also get melting of the tabs from where the transformer connections are friction fitted to the circuit board. Since this damage is on the output side of the charger I interpret this to be a hit from the fence side. I also get situations where the rectifiers and the associated circuit for controlling the firing of the SCR gets knocked completely at times off the printed circuit board. These hits I interpret as incoming hits from the utility lines. In your drawing am I correct that the fence hot wire is connected to the heavy pointed conductor at the top left? I do not have the angles arranged to exactly match what you have but I will work on trying to achieve that. Again Thanks

[Harry Chickpea]

Thanks for the schematic! I need a little more info if you have time. I understand the need for the minimum resistance on the earth ground.

OK

Where the word charger is printed this is the output of the fence charger hot wire if I am reading it correctly.

Correct

I understand the choke and its location.

OK

I also understand the 16 gauge fine wire and I understand the low amperage and the high voltage output.

OK

What I do not understand is that in my own setup I have a fuse holder for a Littlefuse brand glass encased 1 amp fast blow fuse that is only a few thousandths in diameter wire inside.

Very familiar with Littelfuse. Good for many applications, marginal on something like this. The most effective placement would be in a dry area near the charger. (the SURFACE of the glass can be a conductor for lightning if it is even a little wet and dirty.) If it was anything but an electric fence, addition of MOVs would be a better solution. (An MOV would clamp on the fence bursts as well) http://www.littelfuse.com/products/varistors.aspx

I have an air gap (homemade) that is grounded. The air gap is adjusted to a minimum space from the hot wire to ground to where the hot wire only occasionally will spark to ground through the air gap.

Good.

Yet when I get a strike the fuse blows as I expect it to do but I will still get enough power to sometimes blow the output transformer of the charger apart.

There are various possibilities. I suspect that the ground for the fence is not bonded to the house ground. Bonding the two would help considerably. Short of that you have limited choices. You can use a disconnect switch to break all electric connection to the mains, you can attempt various forms of isolation or you can attempt to create a by-pass route around the charger.

I also get melting of the tabs from where the transformer connections are friction fitted to the circuit board. Since this damage is on the output side of the charger I interpret this to be a hit from the fence side. I also get situations where the rectifiers and the associated circuit for controlling the firing of the SCR gets knocked completely at times off the printed circuit board. These hits I interpret as incoming hits from the utility lines.

Yes and no. What you are noticing are the points where there is the greatest differential in voltage and/or current.



If you note how the electrons propagate from point of impact across the soil, you can see how the voltage potentials of the soil are different in different spots until the charges have equalized.


In your drawing am I correct that the fence hot wire is connected to the heavy pointed conductor at the top left?

Yes.

I do not have the angles arranged to exactly match what you have but I will work on trying to achieve that. Again Thanks

It should improve things, as will bonding the ground near the charger and the main house ground. Stay safe.

[agmantoo]

"I suspect that the ground for the fence is not bonded to the house ground. Bonding the two would help considerably."

You are correct. There is considerable distance between the 2 grounds plus the utility service to the farm has a 3rd ground about 1/2 way between the house and the area where the charger earth ground is installed. From the charger grounds to the utility pole it is ~100 feet then overhead another 100 plus feet by the service entrance cable to the house main panel.
The power for the charger, 240 AC at this point is fed ~ 60 feet underground from the house main panel to a shop building and then ~125 ft from the shop main panel underground to a repurposed milk parlor that has a power panel. Then 120 AC voltage is picked up and fed to the charger which is in a dry location. I was told by the utility company to keep the ground at the utility pole isolated from the charger earth ground but I already had installed the latter and the two are only ~100 ft apart. Your thoughts on whether I should increase this distance plus other suggestions are sought. Thanks

[Harry Chickpea]

The ground used by the power company on its pole can be disregarded.

The gold standard for electric grounds at a home is the single point ground with low earth resistance at the primary entrance. ALL of the utilities tie into this ground - power, cable tv, telephone, etc. Since all of the conductors of electricity in the home then spread out in a star formation, the difference in voltage between the phone and power grounds will be close to zero, even at the ends of the runs.

When you introduce a second ground that is not electrically bonded (#10 or larger copper cable) you create the potential for a class of problems under the general heading of "ground loops." Example:

Lightning does a direct strike on your electric fence. The ground rod for the fence does its job perfectly and shunts the majority of the strike to ground. The soil in that immediate area then briefly holds a bunch of those electrons until they find places to slink off to via trales of ground moisture or whatever. The soil has a certain amount of natural resistance, and the area where the electrons are piling up waiting for a route outta there constitute a capacitor. The drier the soil and the more resistance, the worse the problem is.

In the meantime, your un-bonded home ground has no idea what is going on, any more than it would with a strike a couple of miles away. The ground around it is NOT filled with those electrons looking for a place to go. Looked at in a certain way, what you have done with the second ground for the fence is simply MOVED the charge that created the lightning from the clouds to one area of the soil. It STILL is seeking a way to dissipate and the easy path is now through your charger to the house ground. Oops!

When the electricity in lightning or such charges move, the air in the immediate vicinity is ionized - meaning that the air surrounding the path briefly becomes an excellent conductor. Littelfuses don't mean much to it.

When you bond the grounds that are attached to your star formation of wires, you create ground array where the grounds act together to drain the electric charge. The easy path through the bonding allows the coils, spark gaps and other safety devices to work more effectively.

A key to understanding what is involved is to recognize that an area of soil can be at a million volts potential, but as long as everything around it is ALSO at a million volts potential, nothing will happen. Change one part of that, and you have problems.

[highlands]

I have the choke style and spark gap style lightning diverters on our fences. They work very well. Without them we would lose energizers many times a year - we get a lot of lightning here. With them we only lose about one energizer a year or two (we have three energizers operating at all times). I've watched the lightning diverters and spark gap's work during a storm. Very visually exciting and the energizers behind them survived. Also get surge suppression on the power line side. I use this kind:

http://www.kencove.com/fence/Lightni...detail_MLA.php

and

http://www.kencove.com/fence/Lightni...etail_MWLA.php

Also read this:

http://www.kencove.com/fence/27_Ligh...r_resource.php
http://www.kencove.com/fence/6_Light...n_resource.php

I know they work since at one point I had two energizers going, one with the lightning protection and one with out (both had surge suppression) and the one without got fried. Crispy! Other than that both were the same. The lightning bolts hit across the valley about a mile away so it was EMP being picked up by the fence wire which would be equal on both.

Cheers,

-Walter