Kitz Forum
Broadband Related => Telephony Wiring + Equipment => Topic started by: DANNYG on August 21, 2021, 01:44:45 PM
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After doing some decorating the two copper wires that come in to my property from the telegraph pole got disconnected the connection block was old and broken so i connected the wires to the cable that runs to the master socket.
My worries are the may be the wrong way round and with no identifying makes on the two black copper wires i have no way to tell.
would this have any adverse effects and is there a way to tell?
Many thanks for any help.
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It doesn't matter which way round they are, telephony and broadband lines are not polarity conscious. Not since the days of party lines anyway :)
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Hi, welcome to the kitz forum.
This question would probably be best in the "Telephone Wiring + Equipment" section, however, no harm done and I'am sure one of the moderators will spot and move.
There are quite a number of ex BT engineers on the forum and at least one current engineer who are very well qualified to address your question, in the mean time and in lieu of their responses:
To the letter of the law the telephone/BB line up to the master socket should not be disconnected/re-wired, it's the responsibility of OR via your ISP, not sure what any charge implications would be considering that the current drop wire to internal wiring J/B has in fact fallen apart as you have stated.
My understanding:
The line has approx. 50v. DC across the pair. cores designated A & B, supply source, battery bank at the exchange.
Measured with respect to domestic earth, one line is approx. 0v., other line approx. -50v. DC, ie., the +ve line battery source is earthed at the exchange.
I can't remember which line is designated A or B, I'am sure someone will advise.
To answer your question regarding polarity, no, I don't believe it matters with modern telephone/BB equipment, either polarity should work.
However, please bear in mind the other points mentioned before proceeding with a more permanent repair.
Noted, reply by "licquorice" who is much more knowledgable on these matters while compiling.
Edit: Typo correction.
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I can't remember which line is designated A or B, I'am sure someone will advise.
The formal definition is that B-wire is the more negative of the pair.
How to check:
Connect the positive probe of a DVM to a good earth and test each leg of the pair with the negative probe. The B-wire will show around 50V DC and the A-wire around 2 to 5V DC.
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@b*cat:
The formal definition is that B-wire is the more negative of the pair.
Thanks for the clarification, was sure this would be within your remit!
So, to keep it simple for people like me, the A-wire is connected to exchange battery positive and grounded.
As already stated, somewhat hypothetical by present standards but still good to know.
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Well thank you very much for the response here.
I understand that to the master socket should not be touched however not only was i cracked and broken it was also damp were moisture was coming through the cable opening.
I only cleaned the darkened colouring from the copper then reattached it.
I guess i will see :o
sorry for posting in the wrong section.
Many thanks.
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So, to keep it simple for people like me, the A-wire is connected to exchange battery positive and grounded.
Yes, that's it.
sorry for posting in the wrong section.
It was no problem. :)
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I'am still assuming that the cracked/broken J/B is at the point of entry for the drop wire where it junctions from the heavier external cable to the lighter indoor cable?
If you post a photo of this the ex-BT patrons should be able to advise on the model and a direct replacement should still be available.
I'am not implying of course that you should contemplate replacing this yourself!!
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Hi.
The box was this but in worse condition.
Unfortunately it ended up getting lost.
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This one looks nice do you think BT would put this in the old ones place?
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Ah, an old Block Terminal No. 20/4 (BT20/4), dating from the first half of the 20th century.
Yes, Openreach would install a Block Terminal 80/A (BT80/A) as a replacement.
So, hypothetically, if you were to obtain and fit a BT80/A you would connect it (using the image of the BT20/4 and wiring as an example) with the incoming pair, the orange & white wires, to the B & A screw terminals and the internal wiring, the blue & white wires, to the B & A IDCs. If you would like a more concrete example based, say, upon what you currently have in situ then just take a clear picture and let us see. I'm sure one of us will be able to advise. ;)
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But if the cable gets to where you need it neatly while wired directly into the master socket, don't bother replacing the junction box.
Mine also had one of these that the council cowboy contractors made a mess of so I removed it, drilling a new hole through the wall (instead of jammed at the side of the window frame) and hooked the drop wire in directly to the master socket.
Had a second line fitted since then which involved opening up the master socket I had wired it directly into, the engineer had nothing to say about it.
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All i done was clean it all up remove the junction box as it was such a state joined the wires and place them inside a single gang electrical box with a blanking plate for further accesses its a hundred times better than it was.
My only concern is that the wires are the wrong way around but as ive been told here that makes no difference.
all though i would like it to be as it should.
Many thanks for helping.
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There is no 'as it should be'. Polarity of the connections is entirely irrelevant. On older drop wires, it is impossible to identify which is the 'A' leg and which is the 'B' leg in any case as there is nothing to distinguish them except with a voltmeter.
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There is no 'as it should be'.
I read DannyG's statement of "all though i would like it to be as it should" as referring to using a BT80/A rather than the "single gang electrical box with a blanking plate" which is currently protecting the joint. :)
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My only concern is that the wires are the wrong way around but as ive been told here that makes no difference.
all though i would like it to be as it should.
I read that as one sentence, with the full stop as a comma due to the lower case 'a' hence my reply. :)
Interesting how different people interpret things differently. :)
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Interesting how different people interpret things differently. :)
Yes, indeed. :)
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I'm sorry for any confusion in my posts im not very well educated.
So i use spell check to try and make sense of the babble i write.
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All i done was clean it all up remove the junction box as it was such a state joined the wires and place them inside a single gang electrical box with a blanking plate for further accesses its a hundred times better than it was.
My only concern is that the wires are the wrong way around but as ive been told here that makes no difference.
all though i would like it to be as it should.
Many thanks for helping.
How did you join the wires? As in that case I think its a good idea to get a newer box as suggested so they are joined according to how Openreach would do it. Would avoid any awkward questions later if you developed a fault.
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I twisted them together.
I will be ordering the box tomorrow.
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Hi i received a junction box today could somebody be kind enough to tell what wires go were just out of curiosity while i await bt to fit i have an orange/white a blue/white and a blue then x2 black copper cables.
Many thanks.
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The black pair go under the A and B screw terminals with the orange/white and blue/white on the A and B IDC (punch-down) connectors. The polarity does not matter.
:)
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thank you.