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I have a single cat6 cable currently being used a POE for a doorbell that i do not want to use anymore and I want to change to run 2 hardwired doorbells. Can I use the cat6 wires as power cables if I connect them to a doorbell 16 volt transformer that gets power from the house? Is the cat6 wire gauge strong enough to handle the 16 volts?

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  • Physically probably. Code wise unknown, but maybe(low voltage gets little loving). Insurance would probably say no.
    – crip659
    Aug 17 at 20:14
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It's low voltage and likely low current/power limited and probably fine.

POE is 48VDC, so 16VAC is nothing notable for the wire unless it's at absurdly high current, which is unlikely for a doorbell-type use/supply.

Low Voltage is typically defined as under 50 volts, and has little space in code because it doesn't kill many people, while code is written in blood.

Only possible issue is that typical Cat6 or Cat5e is smaller gauge wire than typical doorbell wire. Which may not matter at all...

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PoE uses about 50V to deliver what is theoretically limited to 600mA, so typically 30W, over wires that are typically #26.

Doorbell transformers ... I've seen 10/20/30/40 Watt ones ... I don't know what all exists ... and at 16V, say a 30W transformer is capable of delivering about 1.9A.

Two problems you might run into:

  • If your wire is long and your chime requires a lot of power, it might not get it from your transformer.
  • If your switch malfunctions and stays closed, you might fry your wire (but probably not). I don't imagine there has been much testing done of this.

According to this

  • max power transmission for #26 is .36A. Does that mean it'll heat up at 2A? One way to find out!
  • Resistance is 40 ohms per 1000 feet. You probably won't use 1000 feet but will the voltage seen by the chime drop more than you want? One way to find out!
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  • #26 is not merely inexpensive, but cheap (in the derogatory sense.) The Cat5e and Cat6 building wire I run professionally is all 24Ga. Patch cables might be lower gauge, but the question appears to refer to building wire, not a patch cord. The question-asker can read the side of the cable they have and determine what it's made of and what size that wire is.
    – Ecnerwal
    Aug 23 at 1:02

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