Electric Fence Triggers Siren When Raining

[Annetta]

Afternoon All

Our 6 year old fence recently started to trigger the alarm during rainfalls. Inspection of the fence reveals nothing: no debris, nothing arcing.

After a few hours of dry weather, fence works perfectly.

Any suggestions of where or what to check?

Thank you.

[ians]

This seems to be a common problem ... my neighbours fence is the same ... as it starts raining you hear the electric fence alarm ... you reset the alarm and it works no problem ...even while it is pouring down with rain ... as soon it its starts raining again the alarm is activated.

There have been 3 electric fence companies try fix it ... without any joy.

[GCE]

Afternoon All

Our 6 year old fence recently started to trigger the alarm during rainfalls. Inspection of the fence reveals nothing: no debris, nothing arcing.

After a few hours of dry weather, fence works perfectly.

Any suggestions of where or what to check?

Thank you.

It is generally dust on the insulators or a hairline crack that the water sits in and tracks str to earth .Difficult to see as it does not " jump " across a gap and create the spark

See if you can get it down to a zone and clean insulators

[Leecatt]

My gutshot reaction would be a cracked insulator.

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[ians]

I want to see if the person who is going to test and issue the COC for the electric fence picks up the fault.

I have a feeling the fence next door has a problem with the cable between the unit and the fence.

My thoughts ... after a couple dry days ... if you take a hose pipe and spray water into the pipe and each row fence insulators ... where ever the insulator is cracked it should activate the alarm ?

IF an insulators is cracked ... why doesnt it activate while it is raining ... would you detect leakage voltage on the steel fence ?

[Leecatt]

In fact the cracked insulator should trigger an alarm, especially if your energizer settings are still configured with their default settings.
Typically the Energizer will trigger the alarm after the return voltage has been reduced below a preset level after a preset time, which is normally 3 seconds or 3 pulses.
A triggered alarm is normally caused buy a high voltage fence cable touching an earthing point for longer than it takes to trigger the alarm.
If the cracked insulator is filled with water and the resistance is so low that on each pulse the voltage drops below the set level (3kv?), then the alarm will sound.


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[Leecatt]

I want to see if the person who is going to test and issue the COC for the electric fence picks up the fault.

I have a feeling the fence next door has a problem with the cable between the unit and the fence.

My thoughts ... after a couple dry days ... if you take a hose pipe and spray water into the pipe and each row fence insulators ... where ever the insulator is cracked it should activate the alarm ?

IF an insulators is cracked ... why doesnt it activate while it is raining ... would you detect leakage voltage on the steel fence ?

I'm thinking that dirty water in the cracked insulator may offer a lower resistance? Once the pure rainwater has replaced it, the resistance is raised and the voltage no longer drops below the threshold. Just a thought

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[Annetta]

We checked and found two cracked insulators.
We had a particularly harsh hail storm a few weeks back and our West fence took the brunt. We also replaced the energizer.

We have had a good downpour since all of the above was done so we hope this has resolved the issue.

Thank you all for your inputs.

[Dylboy]

Intresting thread!

Could an IR test be done of sorts to prove if there is a short of sorts ? I mean a fence is massive volts so it may not be enough but still curious.

Connect one end to the line and the other to the earth wire or wires and then test?

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[Derlyn]

I'm thinking that dirty water in the cracked insulator may offer a lower resistance? Once the pure rainwater has replaced it, the resistance is raised and the voltage no longer drops below the threshold. Just a thought

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@ leecat. I've been following this thread and I think you have hit the nail on it's head concerning the resistivity of rain water. Your point of dirty water as a result of the dust mixing with rainwater and decreasing it's resistivity is spot on. The same happens with municipal water as a result of the chemicals added.

There was a thread regarding instant showers tripping the ELR with Municipal water but working perfectly with harvested rain water.
It can be seen here ... https://www.theforumsa.co.za/forums/...er+resistivity

This has been an interesting and thought provoking post.
Thanks Annetta.

Peace out ... Derek.