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Joined: Jan 2005
Posts: 135
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mkoloj Offline OP
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I dont think he is trying to say that all phones were designed to take power from the 2nd pair he is saying that you could put the transformer that some phones have and locate the transformer remotely and send the power over the blk\yel pair and terminate the plug you cut off the transformer onto that pair and you have eliminated the unsightly "wall wart" wire strung between your wall mounted phone and the nearest electrical outlet. [Linked Image] Now this makes me thing about voltage drop across the run how long of a run can you have without having to worry about it affecting the operation of the set?

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Joined: May 2003
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e57 Offline
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I was reading an article, (mabey linked from another thread) on the history of Quad wire, and it described just that. Red and green for the phone, and black yellow as power for a lighted phone. Not sure if it can still be done..... But it was done at one point in history. (I'm a young guy, 35, and wouldn't know when that stopped. [Linked Image] But have not seen it in my career.)
-------------------------------
Oh wait, some KSU, and PBX systems send power ad data/signaling on other pairs.

[This message has been edited by e57 (edited 01-28-2005).]


Mark Heller
"Well - I oughta....." -Jackie Gleason
Joined: Jan 2005
Posts: 135
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mkoloj Offline OP
Member
Yes the phone systems do send power over another pair but the wall wart transformers are a Class 2 power supply and the wiring has to be rated for that. Which I don't think cat 3 or cat 5 is rated for, but I could be wrong.

[This message has been edited by mkoloj (edited 01-28-2005).]

Joined: Dec 2002
Posts: 1,253
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djk Offline
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What would concern me about that installation is the proximity of the transformer to the phone itself. Depending on how sensitive the phone is to RF you could have a serious humming noise all over your phone lines.

Wouldn't it be easier to just locate the transformer remotely and run the 9 or 12 volt cables to the phone wall plate?

All you would need is a variety of connector options on the plate as many cordless phones and answering machines don't get fed via a pair on the phone jack but rather use a normal round DC connector.

I also wouldn't particuarly like the idea of a transformer burried in the wall where it might be covered up by insulation. Far safer just plugged in to an outlet.

Can't see that device working in Europe with 230V 50Hz systems. It's not usually legal to run phone and power cables in the same box.

Joined: Dec 2003
Posts: 886
H
Member
transformers are a Class 2 power supply and the wiring has to be rated for that. Which I don't think cat 3 or cat 5 is rated for, but I could be wrong.

Communications cables are usually listed as CM. Table 725.61 allows CM to be substituted for CL2.

-Hal

[This message has been edited by hbiss (edited 01-29-2005).]

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mkoloj Offline OP
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That doesn't sound right to me to be putting that 9 or 12vdc over a pair of #24. I also vaguely remember reading in another sparky forum about cat 5 being used as doorbell wire and someone (I won't mention names [Linked Image] ) was holding his ground about using the correct wire for the correct application and I definitely don't feel comfortable having my tip and ring within the same jacket as the 12 vdc that is giving the phone power, I personally like the idea that was presented before using a CL2 rated cable used to locate the transformer remotely.

Joined: May 2003
Posts: 2,876
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e57 Offline
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I use 24ga or 22ga cat 5 for doorbells a lot! (Almost always) As I usually attempt the sale of an expensive intercom, and if they bite, I don't have to re-pull wire. I leave one behind the strike too for door release and spares. http://www.siedleusa.com/home/sbin/siedleusa.asp

(For some of those units you have to have spec'ed wire - but most of the smaller "2-wire video units will operate fine with cat-5)


Mark Heller
"Well - I oughta....." -Jackie Gleason
Joined: Dec 2003
Posts: 886
H
Member
...I won't mention names

Yup, that would be me. [Linked Image]

No, I don't like to see wiring that is intended for one purpose being use for something unrelated.

Cat5 is a communications cable and it gets confusing if it is used for doorbell, thermostat etc. This aside from the fact that the conductors are 24ga and can't handle much current. If you parallel them it gets really confusing to somebody who didn't install it. My philosophy is to use communications cables for communications and the proper cable for other uses. This way you can see at a glance what's what.

As to using the second pair on quad cable for power, I really don't have a problem with it (and the use is related too). Note this is 22ga quad (2 pair) that I'm talking about not 24ga 4 pair cat3 or cat5.

If you look at the cord that is supplied with the transformer it probably is 22ga. Granted it is only about 6 feet long but the power consumption isn't great either.

I can't see the objection to having the 12VDC and the T/R under the same jacket. We know that even low voltage AC will not be a hum problem because this is done routinely. Certainly then DC will not be a problem.

If you are worried about crosses, 12VDC would not even begin to bother the phone if applied across the T/R which normally works with 48VDC.

I'm only pointing this out as one possible way to do this which may be more convenient than a separate wire sometimes. If you are more comfortable with separate wiring that's fine.

-Hal

Joined: Dec 2004
Posts: 329
I
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"If you are worried about crosses, 12VDC would not even begin to bother the phone if applied across the T/R which normally works with 48VDC."

Not to mention that the ringer signal is usually 85-90 Volts AC. So all the phone equipment is rated well in excess of 12VDC.

Joined: Jul 2004
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G
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The black wire in phone cable showed up with the Princess phone, specifically for the light ("It's little, it's lovely and it lights"). Nobody really thought folks would have 2 lines in a home in those days. The older station wire was just red/green/yellow with the 3d wire used for selective ringing in party line service.


Greg Fretwell
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