Discussion in 'Computers, Cabling & Other Miscellaneous Hardware' started by robt, May 21, 2014.
Yes, cat5 does use 24AWG, and you should limit the current to 0.577A per conductor.
Yeah, that's the official spec (for PoE), but I've found that 2A per pair was quite safe and a tolerable voltage drop in reality.
One of the issues with Cat5, is that its often run in big bundles ( 30-60 cables ).. That really makes keeping it cool a problem.
Other thing just to remember, if you are using Cat5, 'pairs', is that if you use a single fuse to protect it, you've got to consider what might happen if one of the wires in the pair becomes disconnected. You potentially then have all the current flowing down one side.
I've actually got a 200W PoE line card from a company called "silver-tronics". (? struggling to remember ).. They used all four pairs to carry power, and put the Ethernet over the top of that.. PoE on Gigabit, you need all four pairs for data transmission anyway.. Theres some pretty good integrated chipsets.. But we digress.
Thanks for that info, it sounds like running the power using two pairs will work. And thanks for mentioning the issue of if one wire breaks, Qiang, that's a problem i hadn't thought of.
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