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Joe Blogs
02-07-2007, 07:39 PM
Some friends of mine recently got broadband through Telecom with a wireless Dynalink modem (not sure of model number). They breed bulls for a living so have a fairly grunty electric fence system which covers most of the farm and surrounds their house. They have no trouble with the broadband connection but the wireless to their laptop will not work while the fence system is alive. Turning the fence off is not an option.

Can anyone advise us if there a way around this with suppressors, whatever or something.

Myth
02-07-2007, 08:03 PM
Have they tried turning the fence off for a short time to see if it is the fence that is causing the interference? It could be any number of things (including a dodgy wireless signal from the laptop)

Joe Blogs
02-07-2007, 08:15 PM
Have they tried turning the fence off for a short time to see if it is the fence that is causing the interference?Yes that is totally black and white. The wireless to their laptop will not work while the fence system is alive and works perfectly when the fence is switched off.

godfather
02-07-2007, 08:18 PM
Have they tried turning the fence off for a short time to see if it is the fence that is causing the interference? It could be any number of things (including a dodgy wireless signal from the laptop)

I think that was covered:
"They have no trouble with the broadband connection but the wireless to their laptop will not work while the fence system is alive."

There is a hell of a lot of wide-band energy in an electric fence, although I would have doubted that it would extend into the Gigahertz region it may well do. It may well be radiating directly into the wireless device electronics at lower frequencies.

Short (microsecond) bursts of energy could be enough to cause packet error.

I have seen exceptional disturbances where the fence extended for kM, but only at lower frequencies.

Improving the the electric fence earth is one place I would start. Cures most problems, but a seriously good earth away from the power mains earth is needed.

Joe Blogs
02-07-2007, 08:28 PM
Improving the the electric fence earth is one place I would start. Cures most problems, but a seriously good earth away from the power mains earth is needed.That sounds like worth looking at, when I went for a short walk I could hear it clicking, not the click from the supply unit but coming from the wires so maybe its tracking down a bit of gorse or whatever.

Joe Blogs
02-07-2007, 08:37 PM
PS: When the fence is off the bulls make a b-line for the dairy farm down the road.

Poppa John
02-07-2007, 08:45 PM
PS: When the fence is off the bulls make a b-line for the dairy farm down the road.

Surprise, surprise. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! PJ:D :D

Myth
02-07-2007, 09:26 PM
I think that was covered:
"They have no trouble with the broadband connection but the wireless to their laptop will not work while the fence system is alive."
I thought as much, but was clarifying that the obvious had not been overlooked (as is so often the case)

bgi
03-07-2007, 09:27 AM
Electric fence requires the electrical earth return path.
These earth currents can be quite strong...
on a wet day standing next to the main earth pipe the impulse can
be felt in bare feet. Agree with the earlier post, the impulse current is
probably running via the Lan or Wireless hardware.

The fence unit will need it's own earth system, away from the domestic
equipment. On this note, the deeper the pipe in the ground the better,
( inverse square law thing...twice as deep 4 times the ground area or something like that :-/ )
I remember ramming a couple of 6 meter 2 inch pipes, standing on a
workshop roof to get them started.

cheers

BGI

JackStraw
03-07-2007, 12:20 PM
Not totally on topic but. When we had our house rewired the electrician installed a new earth spike. This 2 meter steel rod looked as if it was going to be a hard job banging it into the ground, but no. The guy just stabbed the pole into the ground, pulled it out again and filled the hole with water. He then proceeded to work the pole up and down in the hole. To my surprise the pole just started to slide into the ground with little or no effort, just its own weight really, until, there was just a few inches above ground. He told me that it works on the same principal as liquefaction that you get in earthquakes. Guess it wouldn't work in solid rock though. :D

supertrouper
03-07-2007, 01:12 PM
Most electric fence installations leave a LOT to be desired. I have often found situations where a piece of gorse is touching a fence, a crook insulator is arcing over, or the earth connection is inadequate - all causing a lot of interference to sensitive communications equipment.

All too often, farmers have the "She'll be right mate" attitude to electrical things - and fences are no exception. In other words, as long as it's keeping the stock in, there isn't a problem.

You effectively have a VERY big long-wire antenna - into which you are dumping a large amount of energy every few seconds. A better spark-gap transmitter there never was!

I have a friend up north who recently had broadband installed. Somewhere, within a 5km radius of his house, is a farm with a crook fence issue. The clicking in the phone is distinctly audible - but Telecom's response is "We will send you out a pamphlet which tells you how to deal with the issue - but we won't do anything to help".

So, it's up to the consumer to go around all the neighbouring farms and find out whose fence is causing the problem, where it is, and ask the owner to rectify the situation.

I am sure that if a shorting fence was interfering with Telecom's own equipment they'd be out there lickity-split and have it dealt to.

I can understand it causing problems with the Wi-Fi.

Before my friend was on broadband, he had dial-up - and invariably it just refused to connect to the line card at the exchange. Listening to the line, it would simply keep trying to associate, and eventually give up.

On the rare occasions when the fence was turned off and the line was noise-free, the dial-up worked just fine.

The solution here, as others have already indicated, is to fix the fence system up.

You need a "Megger" - which can look at the resistance of the fence line to ground - it should be in the millions of ohms (disconnect from the fence unit first!)

If it is low, then you need to walk the miles of fence you have and megger from different points to try to isolate the faulty section.

Joe Blogs
03-07-2007, 08:23 PM
Thanks everyone. The info will be passed on.

Joe