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Author Topic: Lightening arrestors  (Read 4170 times)

waltergmw

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Lightening arrestors
« on: April 10, 2012, 09:34:36 AM »

@ BS,

Re your comments on the other thread mentioning discharge tubes:-

Around here we have some of the lightening protection units still connected although the "fuses" have been removed and the earth wire often disconnected.
However I believe this can cause tap difficulties on ADSL / VDSL lines ?

Have you heard of this situation in the North West and are there any instructions about it ?

Also, do you know if there is any line protection applied in a FTTC unit ?

Kind regards,
Walter
« Last Edit: April 10, 2012, 10:55:36 AM by waltergmw »
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silversurfer44

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Re: Lightening arresters
« Reply #1 on: April 10, 2012, 10:02:30 AM »

Sorry, I thought this was a thread about a new TV show, about extra fast police.
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Colin II : It's no good being a pessimist, it wouldn't work anyway.

waltergmw

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Re: Lightening arresters
« Reply #2 on: April 10, 2012, 10:55:10 AM »

@ SS44,

My apologies that my spelling checker has stayed in USA Mode, but I'll change the spelling.

Kind regards,
Walter
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Black Sheep

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Re: Lightening arrestors
« Reply #3 on: April 10, 2012, 03:19:25 PM »

@ BS,

Re your comments on the other thread mentioning discharge tubes:-

Around here we have some of the lightening protection units still connected although the "fuses" have been removed and the earth wire often disconnected.
However I believe this can cause tap difficulties on ADSL / VDSL lines ?

Have you heard of this situation in the North West and are there any instructions about it ?

Also, do you know if there is any line protection applied in a FTTC unit ?

Kind regards,
Walter

Sorry Walter, you'll have to be a little more specific as to what type of Lightning Protector' ?? On Business Systems, the EU can still insist on having LP fitted by us, but again these are generally 'Gas Discharge' tubes. I've not seen any LP utilised on residential premises though. The only thing that comes near it is if working on premises that fall into the Hot Site category (within 100mtrs of a Generating Station) and electrical seperation units have to be installed.

To answer your last question about LP in FTTC, I'm sorry but I've not ever been involved in a FTTC build so can't help there I'm afraid. :)


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waltergmw

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Re: Lightening arrestors
« Reply #4 on: April 10, 2012, 07:19:19 PM »

@ BS,

Here is one I prepared earlier !

Kind regards,
Walter

[attachment deleted by admin]
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Black Sheep

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Re: Lightening arrestors
« Reply #5 on: April 10, 2012, 07:51:35 PM »

Ha ha ha ...... I can read that there's lightning protectors, but can't actually see through the MC32 joint they are apparently enclosed in.

From personal experience, I have only ever come across UG/OH LP's once in the last quarter century. This was about 4 yrs ago and was the reason DSL wasn't working at a Waterboard Pumping Station. All circuits have LP's in circuit on the MDF, some are 'Gas Discharge' tubes (PSTN only), others (namely for DSL/ISDN/PW's) are made up of semi-conducting devices. Therefore, it doesn't matter that we 'cut out' the old ones left in the network.

My only disclaimer would be that these comments relate to where I work, I don't know if you have different 'rules & regs' locally where you are, or if that feed in the picture is for a site-sensitive dwelling ??? I wouldn't have thought so though. :-\
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waltergmw

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Re: Lightening arrestors
« Reply #6 on: April 10, 2012, 09:09:21 PM »

@ BS,

When chasing one of many faults on this infamous overhead run I accompanied the engineer who was making a forlorn but valiant attempt to cure our vary nasty noise problem.
This is the first o/h section of the lines.
I know that the unit is connected via a 50 pr (I think) cable to an u/g joint which has a .9 mm u/g feed from across the road and the outgoing 0.5 mm catenary cable.
At that time the earth wire was neatly coiled up under the unit indicating that it was no longer in service.
I suggested the engineer cut this away in case it was acting as an aerial but to no avail.
The engineer then opened the u/g joint to discover most, but not all, twisted pair gel crimps had three wires in them indicating that there was a tap configuration still in cct.
I do not know, but I strongly suspect, that some ccts still have tap connections although the engineer did remove the tap section for "our pair".
The engineer suggested it would take about 2 - 3 hours to remake the joint properly so we did not hesitate in beating a hasty retreat !

Kind regards,
Walter

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Black Sheep

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Re: Lightening arrestors
« Reply #7 on: April 10, 2012, 09:18:31 PM »

Yup, that confirms my suspicions Walt. Your scenario was exactly like the one I mentioned in the post above. The engineer has cut the old-style LP out of the circuit, and recrimped the pair of wires directly together. 

As mooted previously ....... all LP is carried out in the Exchange. Additional LP can be obtained if required. :)
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Black Sheep

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Re: Lightening arrestors
« Reply #8 on: April 10, 2012, 09:26:51 PM »

I quickly nipped down and took the lid off that joint, Walter. I took this picture of the inside .............

[attachment deleted by admin]
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waltergmw

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Re: Lightening arrestors
« Reply #9 on: April 11, 2012, 12:11:40 AM »

What a resourceful fellow you are BS !

I'm sure we all agree that this whole assembly would be far better not being there !

I've also seen two rotting asbestos tube covered ground pillars elsewhere probably doing the same sort of job, but they had clearly been properly decommissioned, even though the units were left in place.

It still begs the question, particularly for rural overhead lines, how well the FTTCs will withstand even nearby lightning strikes. Given how long it takes the bean counters to provision a couple of new DSLAM line card modules, there will be some VERY IRATE customers if they observe a roasted DSLAM sitting there for the odd month or three ! I also would not relish having to chip the sealing compound out of the ducts to replace the cables and IDC (Krone) blocks in that "roasted joint" FTTC.

Kind regards,
Walter
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