Cat5 for Power buss and Turnout Power

Discussion in 'DCC & Electronics' started by Connor, Feb 17, 2005.

  1. Connor

    Connor Member

    I work with computers and do allot with Cat5 cable. We have something called PoE (Power over Ethernet) which is basically using 2 of the 4 pair of cat5 wire for the + / - for power. I.E they DOUBLE up on the wires. Use 1 pair for the + and 1 pair for the -. What I'm wondering is, if that's going to work for Power buss and Turnout Power/Control.. I think a single wire is around 26 gauge, so that would basically double the size of the wire. They use voltages ranging from 5 to 12 to 24, to -24/+24 (which is 48) with enough apps to power things like VoIP phones, Wireless Access points etc..

    Thanks, Billy
  2. CalFlash

    CalFlash Member

    I understand a lot of people use it for the cab bus but even doubling it up may be marginal for anything expected to carry any substantial current. It should be adequate for most switch machine wiring, signaling etc.
  3. Connor

    Connor Member

    I've been reading people are using 12 Gauge wire for power bus, I find that hard to belive. 12 Gauge wire is used on 120v 15 Amp house hold electric sockets, 14 Gauge for Lights (and switches).. I think that's overkill, but, I've never ran anything DCC so, I don't know.
  4. Matthyro

    Matthyro Will always be re-membered

    Connor it depends on the length of the power bus. In my case it has to go at least 40 feet and I found 18 gauge does the job fine with my Digitrax . I agree that 12 and 14 gauge is overkill
  5. Connor

    Connor Member

    My layout is a 4x8 and I plan on addind another 4x4 section on it later on..
  6. Matthyro

    Matthyro Will always be re-membered

    At that size Connor you can probably use that Cat 5 cable if it can handle the amperage without getting too hot.
  7. nolatron

    nolatron Member

    I used 14 gauge for the DCC power bus (smallest hardware store had) around the layout, but for my turnout wiring with tortoise switch machines I'll be using cat5 cable.
  8. Connor

    Connor Member

    Also thinking about using the connectors used for Hard drive power (those clearish white connectors with 4 wires) for hooking up the feaders to the main buss, I can get a bunch of them from Y's and converters and dead PC power supplys.. Looks like most of them are feed using 20 gague wire. If I use those, I'll go with a bigger gauge wire and use cat5 for the switch machines.
  9. CalFlash

    CalFlash Member

    Wire gauge recommendations for DCC wire runs are based on known resistance and loss factors. For lengths in the range of 40' or more, 12 gauge stranded is the recommendation. The difference in the cost isn't that much up front and I'd rather pay it now than pay it later in terms of problems or potential damage to my system. The system MUST be able to detect a short circuit immediately to be able to shut down to protect itself. Adequate wiring assures this.
  10. Connor

    Connor Member

    OKay, Cat5 is 24 Gauge, which is 0.0201" 12 Gauge is 0.0808", 2 24 gauge wires would be aprox .0402" which is very close to 18 gauge wire which is 0.0403" At least from what I can figure out.

    Thanks, Billy
  11. Fred_M

    Fred_M Guest

    Nope Connor. It's area of the cross section. It's not a proportional equation. pi*radius squared will need to be equal. I don't feel like doing the math but its more like 5 or 6 off the top of my head. Fred
  12. railwaybob

    railwaybob Member

    For a discussion of the thickness of track power buss, visit my website at

    Cat 5 will definitely not do for the track power buss. You need wire that will carry the full amperage. The reason is not to power your locomotive. The reason you need this thickness is to allow the command station/ booster to detect that there is a short and to shut down. If you are using Cat 5 24 AWG wire and you short, the command station/ booster will only see the short as a load and continue to supply power. This will result in a high pitched squeal in the tracks. But you command station/ booster will not emit those 3 beeps and shut down. You will either damage the command station/ booster and/or the decoder. If you happen to land on some plastic, you may even melt the plastic.

    Typically, when you short, you get the full wattage of the command station/ booster going down the tracks. This is about 80 watts (16 volts x 5 amps = 80 watts). Which is enough to melt plastic.

    Bob M.
  13. theBear

    theBear Member

    I've said this before and it always bears repeating.

    You wire to handle the maximum power that the power supply can provide.

    If the supply can put out 3amps at 18volts the wire must be capable of handling at least 3 amps.

    Anything less is inviting a fire.

    As Fred said the current handling capability is directly related to the area of the cable cross section.

    There are tables for this. Be safe use them.

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