Cat5e with telephone & low voltage power in the same cable (1 Viewer)

[Tim*12]

Hello,

I am wiring in a phone in my home theater and have a question regarding cat5e. I have a phone/answering machine that requires a power supply which is currently in a different room in the house, which I want to put in my HT.

Let me see if I can explain this to make sense:

The power supply 'connector' (onto the phone), is cut off, and two wires (from a 4 wire flat phone cable) are spliced on to the two power supply wires. The power supply then plugs into an outlet near the phone patch panel, eliminating the need to have a cord reaching from the phone itself to the nearest outlet wall. Everything runs through the phone cable.

What I would like to do in my HT is run new cat5e to this phone, and run two wires for the phone and two for the low-volt power supply. What I don't know is if this is a good thing to do, or if I should not be running a power source, even low-volt, next to the phone wires in the same cat5e cable. I didn't know if I am setting myself up for an interference problem or not.

Any advice would be appreciated. If I need to run two cat5e cables to avoid having the power run in with the phone run, I can do that too.

Thank you for your help!

 

[WarrenHH]

Being as you are going to lob off the connector from the power supply anyway, why not take a piece of cable about the same length as you will be using in the project, make up the cable out in the open air, and plug it in, and give it a short trial.

If you have no trouble with the mock up rig, I would think you would be safe to assume you will have no trouble in the permanent installation.

You might consider twisting two or three conductors of the c5 together for each side of the power as well, unless you are planning to use them elsewhere.

If you do have problems, and you say you have room for two cables, try running a length of like 18/2 shielded cable for the power and I would think that would do the trick. I don't imagine you quite need 18ga wire, but it is a common size and not any larger than a c5 line.

Most you are losing is a piece of cable at worst.

I like the logic of your idea!

Warren Holm

 

[Wayne A. Pflughaupt]

It shouldn’t be a problem, Tim, as long as we're talking about telephone service here.

Matter of fact, the Phone Company used to do the same thing. If you remember the old “Princess” phones they used to use back in the ‘70s, they had back lighting of the push buttons that was externally powered. They would plug a transformer into an outlet near a secondary phone jack (i.e., back in a bedroom somewhere) and run a wire from it into the nearby phone jack. Inside the wall box, the transformer lead was spliced into the phone line, which gave both phone service and voltage for all the jacks in the house.

I did the same thing many years ago for a wall phone/answering machine I had. I didn’t want a power cord dangling down the wall to a wall-wart, so I put the transformer in the attic and spliced into the phone line going down to the wall-mounted jack. Then in the wall box at the jack, I spliced in the plug end I had clipped off the end of the transformer lead. The result: I was able to supply power for the answering machine with no visible wires. Looked very nice; never had any problems.

Regards,
Wayne A. Pflughaupt

 

[Tim*12]

Sounds good! Thank you Wayne.

 

[Justin Bowser]

Low voltage/current DC shouldn't give you any problems. If you get to higher frequencies and square waves you might hear stuff coupled to the phone if you don't keep the pairs straight.

I remember installing some RS232 terminals and printers in a warehouse once (long time ago) and hooking into existing wire. If somebody was paged when the printer was printing a ticlet you'd hear a buzz. Turns out they were too cheap to run new cables like we told them to and just "borrowed" some wires from some existing cables and ran them to our patch panel.

Justin B.