TELECOM Digest OnLine - Sorted: Re: Wiring Two Lines on One Jack

Re: Wiring Two Lines on One Jack

Marcus Didius Falco (
Fri, 11 Mar 2005 21:34:59 -0500 responded to on the topic of
Re: Wiring Two Lines on One Jack on Fri, 11 Mar 2005 06:21:25 -0500

> wrote:

>> Hi,

>> I would like to wire one jack for two lines. Here is the setup of the
>> wires after opening the jack.

>> The red screw terminal has two blue and 1 orange wires connected to
>> it. The green screw terminal has 2 white/blue and 1 white/orange wire
>> connected to it. I'm just curious as to why there are 3 wires
>> connected per terminal.

>> The yellow an black screw terminals are not connected to any
>> wires. Now what should I do to be able to access a second line?

>> Thank you!

>> [TELECOM Digest Editor's Note: Red/green is traditionally one pair;
>> and yellow/black is traditionally the second pair. You want to use
>> the unused yellow/black screw terminals for your second line. Can
>> you tell us more about the _type of phone instrument_ currently in
>> use on your (I presume) working single line? With no other knowledge
>> it is difficult to answer your question; was this/is this part of
>> a business phone arrangment? Does the pair which is 'wired' at
>> present go to a working instrument? PAT]

> As Pat says red-green and black-yellow are what you care about. You
> (actually the telco does this when you sign up) would normally add
> the extra line to the yellow-black at the box where the phone enters
> the premises. The extra wires sound like they go to extra phones.
> If that box (with extra wires) is outside the premises you might
> want to ask the telco or the cops unless those wires clearly go to
> extra phones or devices you know about.

Many years ago the standard was somewhat different, and the yellow
wire was sometimes used as a ground. Then, for a time, I think the
yellow wire was used to power the lights on princess phones. Almost
certainly the yellow wire is either dead or shorted to one of the
other wires. Check this with a volt meter.

In any event, with modern equipment you can use the red-green and
yellow-black pairs as described by others.

As others have said, your wiring is almost certainly from jack to jack
in a loop topology (not a star pattern). That is, there are one or two
loops of wire through the house, originating and terminating at the
service entrance. Each wire is normally continuous. If a wire is not
continuous, but is a sort of spur, this can work for telephone, but
will sometimes act as an antenna and put noise on the line.

Post Followup Article Use your browser's quoting feature to quote article into reply
Go to Next message: Choreboy: "AT&T Billing"
Go to Previous message: Diamond Dave: "Re: Long Distance Carrier Verification"
May be in reply to: "Wiring Two Lines on One Jack"
Next in thread: "Re: Wiring Two Lines on One Jack"
TELECOM Digest: Home Page