Electric fencing, circuits and leakages.

emaherx

_Brian wrote: »

For a mains fencer it’s recommended to have 3 1meter earth rods min 1 meter apart.

That's a fairly general guide and will do most situations. It should be something like one meter of earth rod for every joule of power in the fence unit. So a 6 Joule fencer would ideally use 6 meter earth rods or 3 2 meter earth rods. But soil types vary and usually in Ireland 3 1 meter earth rods will do most farms.

_Brian

Nekarsulm wrote: »

As far as I know, when electricity was being discovered this is what people thought.
So ever since, this has been how its been labelled.
You can see the way they were thinking, after all, lightning arc's to the earth.

Interestingly if you watch slow motion videos lightening can ark up from the earth too.
Actually slow motion videos of lightening are incredible to watch.

https://youtu.be/6NZ7BollRo4

Nekarsulm

emaherx wrote: »

Would it hurt any more/less?

Like the difference between a kick and a slap!

Say my name

_Brian wrote: »

Interestingly if you watch slow motion videos lightening can ark up from the earth too.
Actually slow motion videos of lightening are incredible to watch.

https://youtu.be/6NZ7BollRo4

I'm pretty sure that, when you posted about the lights dimming from a lightning strike on the wire that this is actually volts being drawn upwards from the power line prior to the lightning making the connection to ground.
If you're in a house during a thunderstorm the lights dim just before you see and hear a lightning strike.

_Brian

Say my name wrote: »

I'm pretty sure that, when you posted about the lights dimming from a lightning strike on the wire that this is actually volts being drawn upwards from the power line prior to the lightning making the connection to ground.
If you're in a house during a thunderstorm the lights dim just before you see and hear a lightning strike.

It’s something I heard during a talk by an esb engineer at work.

Say my name

_Brian wrote: »

It’s something I heard during a talk by an esb engineer at work.

They could be correct on the lower resistance in the line. I don't work for the esb so I won't argue that.

But every strike produces a diming effect in houses near the strike but not every strike hits the power lines.
House alarms will often start milliseconds before a strike is visual and audible.

Edit: I was looking a little bit into and (I think) it's those ground to cloud charges that flow through the air up to make the circuit that hit the power lines below a thunderstorm that then take the power from the lines to the ground temporarily and thus you have lower resistance on the line as the electricity is being put into the ground beneath the lines for a fraction of a second.
That's not saying you can't also get strikes on the grid from above.
But I wouldn't be standing beneath power lines during a thunderstorm just in case.

_Brian

Just on fencing.
Last year I bought a few packets of spring hate kits in Clarke’s of Cavan, €8 for the sets with handle, spring andntwo insulators.
Went back in there few weeks ago and they were €15 😱, some increase in 12months.

emaherx

_Brian wrote: »

Just on fencing.
Last year I bought a few packets of spring hate kits in Clarke’s of Cavan, €8 for the sets with handle, spring andntwo insulators.
Went back in there few weeks ago and they were €15 😱, some increase in 12months.

€15 is quite expensive, but they are €17 in glanbia. A quick Google shows they vary from €4 to €18 for 5m gates which is a massive variation can't see there being that much difference in quality and all of the results were Ireland or UK not the usual Chinese importers.

I've being using https://www.electric-fence.co.uk/ for electric fence parts that I'm not in a hurry for, I find them quite reasonable.

_Brian

emaherx wrote: »

€15 is quite expensive, but they are €17 in glanbia. A quick Google shows they vary from €4 to €18 for 5m gates which is a massive variation can't see there being that much difference in quality and all of the results were Ireland or UK not the usual Chinese importers.

I've being using https://www.electric-fence.co.uk/ for electric fence parts that I'm not in a hurry for, I find them quite reasonable.

Yea I’d seen that site, good to know they are ok to order from.

emaherx

_Brian wrote: »

Yea I’d seen that site, good to know they are ok to order from.

Yea, put in a fairly big order with them in early spring. Solar fencer for out farm, 80 angle steal posts, a few packets of insulators and a few other bits and they all arrived in about 10 days.

_Brian

emaherx wrote: »

Yea, put in a fairly big order with them in early spring. Solar fencer for out farm, 80 angle steal posts, a few packets of insulators and a few other bits and they all arrived in about 10 days.

We’ve expanded fencing here and all field gates are being replaced with spring gates as they need replacing.

dar31

_Brian wrote: »

We’ve expanded fencing here and all field gates are being replaced with spring gates as they need replacing.

Eletric Bungee cord would be far better, spring wires only get in a black knot over time.

_Brian

dar31 wrote: »

Eletric Bungee cord would be far better, spring wires only get in a black knot over time.

Must try that.

emaherx

_Brian wrote: »

We’ve expanded fencing here and all field gates are being replaced with spring gates as they need replacing.

Yea, really trying to improve all fencing here as I'm away all day and want to be confident cattle are where I left them. Concentrating on perimeter fences over the last few springs installed some permanent Clipex fence along weak road boundaries. Have allot of temporary style mix of plastic and metal posts around all other boundaries which I will reuse on internal fences as I install more permanent fencing. It's a disjointed farm in 5 separate lots so have allot of boundary fences, when I started it seemed like an impossible task but allot has been achieved in the past 2 years.

Weak battery fencers on out farms is the biggest issue now, but after using the solar unit for the last few months I'll be investing in a few more.

MrMusician18

_Brian wrote: »

There is also the issue of resistance at joints, leakage at insulators and the difference in wire types.
We have heavy steel wire at the permimiter but inside it’s a mix of steel tie wire and white. With the combination of earths, connections and potentially leaking insulators it’s massively complicated.

Power does strange things in lines that you wouldn’t expect.
Ever notice during a lightening storm lights dim occasionally ? That’s a strike on the grid, you’d expect a surge rather than a dim. But locally to the strike the burst of power temporarily lowered resistance in that section causing local power to flow towards the lowered resistance and the result can be a dip in power at other local locations.

I would never test one section of fence and presume the others are fine.


Obviously the use of copper wire to join sections is a big no no. Where the copper and steel wires join they are dissimilar metals on the presence of voltage and damp and so create an oxide film between them which over time insulated them from each other, causing a gradual drop in power transferred until eventually no power is transferred.

This is an aside but the above is not correct. The lights dim because there is a voltage drop due to a temporary fault on the adjacent line and the automatic recloser is attempting to rectify the fault.

Capra

_Brian wrote: »

Must try that.

Even at that I would only go with Strainrite solid core bungee. The standard cheap stuff you get in the Co-op will break down and lose voltage after a few years. Solid core is way better, pretty expensive but well worth it.

L1985

Another very basic question.....I have two lines going off different directions that I then loop together so that if one is disconnected then the other one keeps going-so a back up. So the two currents meet. But I was thinking there-is this the right thing to do or would it cause the fence to lose power?
And also with two battery fencers? Can I use two fencers in the same area to get the fence stronger?

emaherx

L1985 wrote: »

Another very basic question.....I have two lines going off different directions that I then loop together so that if one is disconnected then the other one keeps going-so a back up. So the two currents meet. But I was thinking there-is this the right thing to do or would it cause the fence to lose power?

That's fine, but disconnect them when testing fence in case there is a fault masked. Electricity will find the path of least resistance.

L1985 wrote: »

And also with two battery fencers? Can I use two fencers in the same area to get the fence stronger?

No you cannot do this. If using 2 units have 2 independent fences with no possibility of being linked.

emaherx

What power are your battery fencers In Joules?many are designed for strip grazing (less than 1km of fence) and might be as low as 0.2 joules.

Here is a rough guide.

L1985

I think you need to be an electrical engineer with all of this! It’s a great help so thanks . The first one I was sure it would be fine but I was also sure with my first question so...!
I only chanced the two fencers a few weeks back so I won’t be doing that again I’ll divide the lines and might get a solar fencer for up there anyway.

I don’t know the joules-they are the elephant ones? Just been having problems with them and it’s bullocks who are on the bold side and can smell when the fence weakens! It’s caused issues the past three years since I’ve been putting them up there so I might seriously look into the solar. It’s only a mile of fence bit the fencers don’t seem to be lasting.

Buford T. Justice XIX

L1985 wrote: »

I think you need to be an electrical engineer with all of this! It’s a great help so thanks . The first one I was sure it would be fine but I was also sure with my first question so...!
I only chanced the two fencers a few weeks back so I won’t be doing that again I’ll divide the lines and might get a solar fencer for up there anyway.

I don’t know the joules-they are the elephant ones? Just been having problems with them and it’s bullocks who are on the bold side and can smell when the fence weakens! It’s caused issues the past three years since I’ve been putting them up there so I might seriously look into the solar. It’s only a mile of fence bit the fencers don’t seem to be lasting.

The first thing would be to sort out your earths on the fencers. Put in enough of them and connect them properly to each other and keep the soil around them moist. Use the insulated coils of wire and metal clamps to connect each earth to each other and make sure they're good and tight so there's no chance of them coming loose.

Then test the wire before connecting it to the wire and see what the output is.

Then clean off any vegetation on the wire and move it up away from grass. That'll have to be done regularly and keep an eye on the current in case it drops. You'll need a reading of at least 3 on the tester to keep animals inside.

L1985

Ok so continuing on my electricity based education which I’m realizing is sorely lacking ....Earthers-I get that they are a metal spike into the ground but why do you need more then one? And why if it’s an earther it increases the efficiency but if it’s hitting off a pole accidentally it lowers it?
Also if I’m putting in more then on earther why should they all be in the same spot? And I’m getting from the above all have to be connected ? And why is more then one better? We have only one at home so looking at driving a second one based on this anwser!!
Btw you can see I was a fun child-I hate being told “because” and that’s my dads favorite anwser!!

Say my name

The more surface area of an earth you have the greater the negative pole on the fencer unit and the greater the positive charge going out along the fence line.
If there's more of an earth on the fence line than your earth bars the polarity of fencing unit gets reversed and the shock goes into the earth bars and you'll have nothing on the fence line.

So the more bars the better as you'll have a greater surface area and contact with the earth itself but spread them out about 1 meter or more apart joined together with insulated steel cable.

The ultimate earth system would be galvanized reinforcing steel mesh buried in the ground with a bar coming up to connect to the fencing unit. Other people use diatomaceous earth around their earth points to ensure a good connection to this planet.

_Brian

L1985 wrote: »

Ok so continuing on my electricity based education which I’m realizing is sorely lacking ....Earthers-I get that they are a metal spike into the ground but why do you need more then one? And why if it’s an earther it increases the efficiency but if it’s hitting off a pole accidentally it lowers it?
Also if I’m putting in more then on earther why should they all be in the same spot? And I’m getting from the above all have to be connected ? And why is more then one better? We have only one at home so looking at driving a second one based on this anwser!!
Btw you can see I was a fun child-I hate being told “because” and that’s my dads favorite anwser!!

Everywhere in your fence you have nice tidy joints, steel to steel.

But where your earth bar enters the ground you have a steel bar trying to make a circuit touching the earth around it, it’s inefficient.

And so the more earth you have the better overall circuit you will make.



It’s all relative to the size of the fencer you have too. You are trying to get a circuit that will accommodate the energy to go around the system.
So a battery fencer at say will require a smaller earth system compared to a large mains fencer which could be 10times stronger.

Nekarsulm

L1985 wrote: »

And why if it’s an earther it increases the efficiency but if it’s hitting off a pole accidentally it lowers it? !

Because those are two different and seperate wires coming from the fencer unit.
Its like leaving one lead off a battery, the clock/toy/whatever simply won't do anything untill the other lead is connected.

emaherx

L1985 wrote: »

Ok so continuing on my electricity based education which I’m realizing is sorely lacking ....Earthers-I get that they are a metal spike into the ground but why do you need more then one? And why if it’s an earther it increases the efficiency but if it’s hitting off a pole accidentally it lowers it?

You use more than one earth rod ideally spaced by 10 feet or more but connected by wire to the earth side of the fence. This is because electricity will find the path of least resistance, 3 rods 10 feet apart will cover 30 feet and will allow the current to return via multiple paths effectively lowering the resistance of the soil.

A metal post touching the line wire is a different situation all together. In a perfect fence with 0 faults the fence is completely open circuit meaning no current will actually flow until an animal comes in contact with the fence. So its about potential difference, the potential of the fence line wire is about 10,000V and the potential of earth is 0V so if you are touching both the ground and the fence you become the load and the current will flow through you and you will feel all 10,000V (especially if you are bare footed like a cow).

In the case where you have a metal post touching the line wire and the ground then you have just brought the earth and the fence line wire to the same potential as they are physically connected by a conductor meaning the potential difference is 0V ie no shock. Due to differences in resistance of the ground, metal post and the line wire there may well be some voltage but it will be closer to 0V than it will to 10,000V

L1985 wrote: »

Also if I’m putting in more then on earther why should they all be in the same spot? And I’m getting from the above all have to be connected ? And why is more then one better? We have only one at home so looking at driving a second one based on this anwser!!
Btw you can see I was a fun child-I hate being told “because” and that’s my dads favorite anwser!!

The earth rods need to be connected to each other and the fencer so for practical reasons they will be relatively close to each other but they shouldn't be too close either (at least 10 feet apart). There are many factors that determine how many earth rods are needed including power in fencer, area covered by fence and moisture of the soil. look at the table I posted the other day. There is no point using 3 1m earth rods with a 0.2 Joule fencer powering 1-2KM of fence likewise not much use having a 6 joule fencer and trying to fence in a 40 acre farm using 1 1/2m rod (however too many is better than too few). If you have inadequate earthing or an under powered fencer unit then you are already at a loss and that's before you add in unintentional earthing from vegetation.


What model of fencer are you using and how much fence do you need to power?

orm0nd

Using 6 earth rods here. 4 metres between each one and in a semi circle. Bonded with a continuous length of covered under ground cable with the insulation stripped at the clamps and covered with a few layers of denso tape.

Previously we had a very small stray voltage reading in the dairy {even with everything bonded} but above sorted it.

BTW our energizer (Electric Shepherd) is almost 40 years old and never missed a beat.

emaherx

orm0nd wrote: »

Using 6 earth rods here. 4 metres between each one and in a semi circle. Bonded with a continuous length of covered under ground cable with the insulation stripped at the clamps and covered with a few layers of denso tape.

Previously we had a very small stray voltage reading in the dairy {even with everything bonded} but above sorted it.

That's a proper job, what sort of area have you fenced?

On the stray voltages were your earth rods anyway close to the parlors earth rods? Or was the fencer plugged in to parlors sockets?

Nobbies

Some here have said when joining your earth bars together, use insulated steel wire. is this a must or is it just somewhat better than using steel galvanised fence wire???

i use the latter myself and current tests well.

Nobbies

Probably being said earlier in this thread but if you want to test how good or bad your earth is.
grip the earth rod/wire tightly in your hand,then put your other hand palm down on the ground

if your getting a shock/tingle your earth is poor.