Kitz Forum
Broadband Related => Telephony Wiring + Equipment => Topic started by: aesmith on March 05, 2017, 04:31:44 PM
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Hi,
We've found the offending electric fence that BT weren't allowed to identify for us. There's no doubt about it, even to the fact that their new mains powered energiser was installed in November, right when the problems started. The lady was very helpful, wasn't aware that it interfered with broadband but now I mentioned it she said for the last month or so it's been really slow giving her problems with Facebook. So perfectly open to working with us to see if we can resolve things.
The fence is a single strand of plastic line with steel conductors, run at chest height on stand off insulators on fence posts. There are two gateways with expanding spring type openings. Mains powered energiser in the stable, lead out cable from there underground and coming up at a gatepost in an adaptable box from which the fence conductor is connected. Not sure what cable type is used for the underground run. There's no phone line at the stable so the energiser and it's earth are around 200m from the telephone cable at the roadside. The fence runs along the road for several hundred yard, above the 50 pair phone line.
First walk around there wasn't anything that glaring. The fence tested full power at all points, and the earth rod gave no reading on the tester at all. Nothing looked like it was shorting. So all I have is points of possible concern. (1) joints in the fence line made by knots rather than joiners. One of those was clicking when I walked round so I've fixed that one (and that seems to have had some effect). There are a few more that weren't showing any sign of problems (2) The earth rod isn't that long, in fact the guy who installed it had some concerns but hadn't fitted a longer one yet as it seems to work OK (3) the gateways, one of which is directly over the phone cable. These join with steel hooks with various degrees of rust.
Any ideas as to what sort of faults I should be looking for? I must say that if my concern was only the effectiveness of the fence, I can't see anything that would worry me.
The attached graph shows the general error rate, you can see three short periods when the fence was off, and what looks like a lower error rate after I fixed the clicking joint, not yet confirmed because I've seen short episodes like that before. My thoughts at the moment are that if this continues, it might be worth going back and fixing all the knots in the same way whether clicking or not.
Thanks in advance,
Tony S
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I think it would be well worthwhile to ensure that every joint in the "active" conductor is sound. Every arc that occurs will be acting as a 1900s era spark-transmitter.
A longer earth-rod may also help. (Just so long as it is not driven into the ground such that it penetrates the buried 50-pair cable.)
Overall, I think the biggest problem (once the above have been addressed) will be that the fence runs parallel to the 50-pair D-side cable and thus coupling between the two will occur.
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I think it would be well worthwhile to ensure that every joint in the "active" conductor is sound. Every arc that occurs will be acting as a 1900s era spark-transmitter.
+1
A longer earth-rod may also help. (Just so long as it is not driven into the ground such that it penetrates the buried 50-pair cable.)
Make sure it does not go through the Mains Cable also ! :'(
Overall, I think the biggest problem (once the above have been addressed) will be that the fence runs parallel to the 50-pair D-side cable and thus coupling between the two will occur.
+1
She if the lady will let you get some stats from her Modem, it may help her as well and other people in the area to you can sort out the problem.
On my problem I had with a neighbors security camera giving out REIN I gently dropped the hint that BT now had the powers to disconnect the the offending persons broadband connection if it was not fixed, odd my REIN interference stopped the next day. :lol:
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Thinking this through I actually wonder if a better earth might make it worse. The better the earth, the more energy goes to the fence. Anything radiated from the earth rod itself has to travel a long way before it reached any telephone cable.
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The problem is the fence wire is a very big aerial. :o
Find out what make the controller is and send an email to the firm to see if they have any idea's to stop/reduce the radiated interference.
Knot info. http://www.agrisellex.co.uk/media//wire-join_detail.jpg
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" .............. electric fences are also able to affect some types of data service in some way, though broadband has been proven to be fairly immune to directly coupled fence noise, but not very good when the fence radiates noise in the RF region, e.g. when the fences sparks across insulators, vegetation or even joints in the wire."
" ............ the quality of the earth at the generator can also have a large influence on the noise level. Guidance is given by the fence manufacturers on how to lay out the earth spikes and check its effectiveness using an electric fence voltmeter (aim for a ground voltage of less than 250V/m from the earth spike)."
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The earth rod needs to be as good as possible, it should also be nowhere near anything grounded on the mains electrical circuits, ie earth stake on a TT system, parts of steel work on agricultural buildings
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Cheers. The stable block where the energiser's mounted is wooden and mains was only brought in to serve the energiser. I couldn't see any sign of an protective earth so I assume that was exported from the source supply (which round here would be TNS). The earth for the energiser is some distance from the phone line, further than our own for example.
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At a guess, the fence system is an induction coil, causing interference like car ignition. The cure there was a series resistor at the distributor and sometimes one at each plug as well. From memory (long time ago !) typical values were 5 to 15 kOhms. This didn't completely stop it but converted the white blob on the TV screen into a white spot. Possibly a coil instead of the resistor might help, provided you don't clobber the voltage pulse on the wire.
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Did you get this sorted ?.
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Did you get this sorted ?.
No. To be honest I was a bit disappointed I couldn't get any of the neighbours more interested, considering that according to BT the fence should be having the same effect on everyone down that 50 pair cable. Maybe the neighbours aren't in fact affected, or just that their non technical. For whatever reason I don't have any actual stats except for my own line.
So from pure self interest I've revved up my Billion router so that even though DLM as stepped me down to a 15dB target, I'm nevertheless running at full speed so my Internet service is effectively normal.
I do still need to fix this properly, because it's going to be pretty impossible to progress any other fault that might occur in the future, with the line currently classified as permanently degraded.
However I'm back to checking the local line just now. Up until last Monday the line was connected without interruption for 30 days at 4128K down, then when we had the sleet and snow I had 10 disconnections over the two days, reconnecting at speeds down to 2752K. To my mind something triggered by the weather has to be a low level fault. I'm looking at joints on the local cable, see whether any of the enclosures are damaged, or the surface run cable maybe ripped by cultivation.