Please ID my cable!

[Lobster]

Can anyone tell me what this cable is/was?

It runs up the side of a postwar end-of-terrace ex-council house, emerging from the ground encased in a steel conduit (scuse the poxy cameraphone photos):

At the top, it runs along the eaves parallel to the guttering, clipped to the ends of the rafters; I opened a junction box under there to find it joining to a new section of cable with porcelain connectors... there seem to be 8 cores, in 4 different colours. Looks a bit thicker than modern telephone cable, but certainly not as thick as 1.0mm2 lighting cable:

cable doesn't seem to have any connection to the property per se, but disappears off along the eaves heading towards next door (who know nothing about it either).

I'm convinced that whatever it is is redundant and can be safely removed, but as a point of principle I'm slightly uncomfortable doing so without being able to at least identify it first! Anyone got any ideas?

Thanks David

[EricP]

No, it's got far too many wires in it for anything I can suggest. But the house deeds might have a clue. Cables like that are usually listed on them specifically, so you might be lucky.

[John]

Could it have been a radio network - Redifussion used to install them I believe. The occupier just needed a loudspeaker with a volume and selector switch.

[Trevor Smith]

cable:

> The cable doesn't seem to have any connection to the property per se,

Back in the seventies in my part of Kent Redifusion used to do a cable TV system that ran from house to house along the facia boards, it only supplied BBC1 & 2, ITV and radio 1 & 2 and it is long gone now but If you had this on your house and didn't subscribe to the service you were given a book of stamps once a year for them having the cable on your house. It's possible that your mysterious cable could be that. Trevor Smith

[Harry Bloomfield]

Lobster submitted this idea :

They were popular pre 1960's.

I would guess at a distributed radio or TV system. I don't think any of the old systems are still in use. Follow the cable to each property and if no one is definitely using it, just cut it off - disconnect at the connectors first, leave it a month to see if anyone complains - then finally remove it completely.

[Dave Plowman (News)]

Long since dead cable TV/radio

[The Natural Philosopher]

Looks like BT's work to me. Those connectors are typically what they use.

Maybe the property once had either lines going to other houses, or a PABX.

[Edgar]

British Relay? But they don't look suitable for TV, only radio at audio frequencies to me. Relations in Workington got something like one shilling per year wayleave for BR cables to run across the facia. (I never saw the cables - or the house - just some paperwork.)

Edgar

[John]

Definitely not BT. I've been a faultsman jointer on BT for 17 years and know that we've never used screwits - I'd say Redifusion.

John

[Harry Bloomfield]

Not BT/GPO wire colours and so far as I am aware, they never ever used Screwits for jointing.

[Andy Hall]

Are you one of those poor souls who sits in a hole in the road under one of those stripey tents rejointing cable?

I believe that some are a few hundred pairs? I imagine that that would require a lot of concentration for which you have my greatest respect.

Question for you. I'm given to understand that at least part of the cable connecting from my house to the exchange is of aluminium. The line loss that I get with DSL is aproaching 60dB which I believe is higher than would be expected with copper. Admittedly I don't know the precise routing of the cable, but if it follows the obvious path would be about 3km. An as-the-crow-flies path or even a convoluted one would not be longer AFAICS.

Where would BT be likely to have used the aluminium cable? closer to me or closer to the exchange?

What would it take to persuade them to change it? I am not thinking of an email to Ben here.

[bof]

In message , Andy Hall writes

I've heard often that Al is worse than Cu for (A)DSL, why is this?

[Harry Bloomfield]

They are, but it all falls into place.

Aluminium could have been used anywhere along the line. It was a matter of copper being expensive in the 1970's and when the particular cable sections were laid.

If it supports voice adequately, that is all you can expect.

[Harry Bloomfield]

bof formulated the question :

It has higher resistance and is more subject to oxidation.

[Owain]

A good fire in a manhole?

Owain

[Andy Hall]

It does?

If there was a time period around the 70s then it is more likely that it was used closer to the exchange.

Except that they and others would like to sell services requiring more than that.

[Lobster]

Thanks all - yes, an old cable TV system seems highly plausible; especially having googled a bit for this.

I can't believe it's in use - especially as NTL/Virgin are in the street, not to mention the usual plethora of satellite dishes - and I would like to just get shot of it forthwith: so if there turns out to be no voltages across any of the wires, would that indicate it's definitely redundant?

David

[Frank Erskine]

The surface of the aluminium tends to oxidise very rapidly (which is why it's difficult to solder) - the higher frequencies used by DSL travel largely towards the surface of the wire, so the wires are more lossy at higher frequencies.

[bof]

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In message , Harry Bloomfield writes

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In message , Frank Erskine writes

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First please excuse me putting these two replies together, but it seems to me that if Al has higher resistance then the for it's original purpose for use in place of copper larger diameter cores would have had to have been used to get the same loss at speech frequencies. If the core is larger diameter then there's more surface for the (A)DSL to travel on. Even if the Al surface does oxidise the high frequencies will travel on the Al surface underneath the oxide.

[manatbandq]

Who says they didn't tolerate the extra loss when Al was used and just use the same or similar dia cable?

MBQ