RJ45 and Cat5 power rating


I have been looking about and can't find the answer and was wondering if anybody could point me in the right direction.

I'm working on a project where I want to use RJ45 and cat5 cables

I want to use 1 pair for the differential data and 3 pairs to carry power (in parallel) but I'm not sure on the power rating of CAT5 cable or the RJ45 connectors.

Does anybody know?


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its low current wire. i can't remember the common gauge on the conductor but its around 24 awg. its ~ 25 ohms per 1000 feet it is suggested that you do not exceed 5 % drop of voltage on the other end. it depends on the length of cat your going to use. longer lengths means less current handling. you can put the pairs together, i have seen it done but don't expect to run lots of current. for example, for a 100 foot run i wouldn't go over 2 amps/ with 3 pairs together you will get aprox 16 ohms of resistance on a 1000 foot run so in a 100 foot run you would get 1.6 ohms. so you mite get like a 3 volt drop if you expect a load of 2 amps in the line for example. you didn't say how large of a load you were expecting to use ? i may have the gauge used for Cat wrong, it could be 22 which would make it even better for you. hope that give you some insight there.

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you could look to a maker for their data sheets...

here's a starting point:

Voltage up round 100VDC (peak of telephone ring signal)

current about 250mA per contact (power-over-ethernet spec puts 500mA at

48V common-mode on one pair coming and another going - less than that has been fatal)
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