why is there 3-wire telephone wire in my house (R, G. Y)

January 9, 2015 at 19:41:48
Specs: Windows 7
My old house telephones are wired with 3-wire cable (Red, Green, Yellow). There is no black wire in the cable. What is the reason?

See More: why is there 3-wire telephone wire in my house (R, G. Y)

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#1
January 9, 2015 at 20:35:03
A single primary phone line only requires 2 wires, green & red. Black & yellow are spares for a 2nd line. I don't know how a 3-wire cable is used.

http://electronics.howstuffworks.co...


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#2
January 9, 2015 at 22:56:17
In the UK a 3rd wire is used as a ring wire.

http://www.robertos.me.uk/html/ring...


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#3
January 10, 2015 at 01:38:26
This wire you're talking about--is it the one from the phone to the wall plug or the one inside the wall going to the plug?

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Related Solutions

#4
January 10, 2015 at 09:05:39
Sometimes unused wires are connected to a spare terminal rather than leaving them hanging around.

Always pop back and let us know the outcome - thanks


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#5
January 10, 2015 at 13:22:00
Which country are you in - as different countries adopt slightly different wiring standards/codes... Are you referring to incoming line or the internal wiring - which may be different to that incoming? Also how old is the wiring in question; as that too may have changed over time; certainly for domestic installations.

In UK the wiring practice (way back in the mysts of tyme) was initially a single cct. incoming; then it was changed to allow for 2 or 3 ccts. incoming. Strangely the current practice is again single service (cct.) only. Which is in effect a return to the original standard installation practice from way back in the mysts of tyme - which was later changed to the 2 or 3 ccts; all this of course prior to the sell off (privatisation) of the olde Post Office telephone services - now called BT... When I queried this (reversion to the old single cct. incoming) with a BT installation chappie - he observed it was to save the cost of copper...; as many (most?) domestic installations generally opt to have only one incoming line... Installing multi-pairs (multiple ccts.) when only one ever used... means a load of unused copper wiring all over the place... I suspect USA/Canada may have gone somewhat a similar "journey"?


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#6
January 10, 2015 at 14:52:48
Yes, where you live is all important, different wiring and different technicalities.

I know you are not UK because Red, Green, Yellow are not used there.

As an aside (re #2), for UK removing that old bell wire whacked up my ADSL speed nicely - something I did years ago. I used to work for BT (in many fields).

Always pop back and let us know the outcome - thanks


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#7
January 10, 2015 at 15:15:16
@ Derek:

Didn't they ever let you work indoors...? I know things changed when the old Post Office became BT... But for the "new management" (comfy warm in their plush offices) to make the rest of the staff work out in the fields... tut, tut, tut...


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#8
January 10, 2015 at 15:26:03
trvlr

I'll PM you.

message edited by Derek


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#9
January 10, 2015 at 18:47:44
The one inside the wall going to the wall plug.

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#10
January 10, 2015 at 23:09:56
How old is the house or how old is it's phone wiring and as already asked, where is the house? If you're in the US there's probably a black wire there too. It may have been cut back to keep it out of the way so you might not see it.

I just opened up a 1960's era rotary phone and it used all 4 wires. It wasn't obvious what each of their functions were as they connected to a single block inside the phone.

It seems like I recall that since modern phones only need 2 wires to function and older homes already had the 4-wire cables then the other 2 wires were used if the customer wanted a second line. That is, the original intent of running a 4-wire cable wasn't to accomodate 2 lines but with newer technology that became possible and older homes didn't need to be completely rewired.

The older rotary phones had those big 4-prong wall plugs so when the newer phones came out using the modular RJ11 plugs the phone company often would come out and rewire the wall plugs anyway.


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#11
January 11, 2015 at 01:38:22
This may help clarify..

http://www.wire-your-phones.com

http://www.wireityourself.com/telep...

And this may be of interest should you ever feel to use cat-5 to extend or rewire your home phone outlets....

http://www.evonet.com/evonet/index....


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#12
January 11, 2015 at 08:55:22
Re #11

Interesting, seems the old differences between US and UK are diminishing.

In the UK clockwork days we had "plan numbers", sheets of diagrams using stacks of wires when you had different multiple extensions arrangements. I've forgotten most of what I knew about this but recall that Plan 4 was the only one with plugs and sockets - monster things. It is all much more simple and convenient now but we kinda hang on to the extra bell wire, although I get the impression many fitters don't bother with it because of the ADSL implications and the lack of need with modern phones.

Always pop back and let us know the outcome - thanks


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#13
May 24, 2015 at 20:12:03
I also have old telephone wires connected to outlets through my house (built in ca. 1930, midwest USA) that have only red, yellow, green in them. Since they are no longer in use, I cut one out, stripped off the outer insulation on about 6 feet of it, and was going to make some simple science demos for my kid. Thats when I discovered the wire looked like copper, but was attracted to a magnet. So far, I havent found much on it's specific installation or use, but it appears my old telephone wire is copper clad steel.

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