I want to transmit data and power over 10 meters at 12 volts with 1 amp. I don't know if I could do it using UTP, because that's a standard for other things. Which standard should I choose? Number of cables needed 4 at least. Frequency irrelevant, slow. The question is; I'm not following the rules of UTP I'm making my own rules, so I suppose I cannot use UTP even if it fits my needs because if someone plugs a computer there it can be damaged. Is there a general purpose standard?

  • \$\begingroup\$ We could use more details: how much voltage drop is acceptable, what is slow (0.01 baud??), why do you say 4 cables (that is 4 times [ power + data ], or is it the wires you intend to use for one power+data?), how noisy is your environment, how sensitive is data integrity, and how to judge between cable cost and end-node cost (is data-over-power worth the effort)? \$\endgroup\$ – Wouter van Ooijen Sep 29 '16 at 9:24
  • \$\begingroup\$ I don't want to know how to transmit the data, I want to know if there is a prohibition on using a computer cable for something else, if someone plugs their computer to this port their computer can be damaged. \$\endgroup\$ – Phil Rv Sep 29 '16 at 10:43
  • \$\begingroup\$ Twisted Pair has better immunity to CM noise than UTP unless you use CM Balun. It also has better signal integrity with lower DM impedance. Protocol should have error detection. BiPhase is most common method \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 29 '16 at 11:35
  • \$\begingroup\$ @PhilRv: Why should there be a prohibition? UTP wires are used for almost every differential lowspeed communication. \$\endgroup\$ – Simon Sep 29 '16 at 11:38
  • \$\begingroup\$ There is no general law against using a cable for anything, but there might be laws against specific use (like fire hazard: current through wires in a pipe, and isolation requirements when mains wires are involved). \$\endgroup\$ – Wouter van Ooijen Sep 29 '16 at 15:41

You should consider Fast Ethernet (100Base-Tx) with power over Ethernet (PoE). You can use a 4 wire UTP for that without the possibility to damage a computer at the other side, but you have to be careful with your current of 1 A. When using PoE, the current flows through the coupling transformers windings and 1 A will probably be to much.

If you are looking for a simpler solution you should have a look at the AS interface (ASI bus).

Or build a custom solution which is a little fiddly and could involve capacitive coupling like shown below (DC free channel coding required).


simulate this circuit – Schematic created using CircuitLab

Answer to your updated question:

UTP is just a standard for wires and does not describe the kind of connector that is attached to it (western RJ45 for Ethernet connections to computers). Therefore you can use UTP without doubts. Aggreed?


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