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Phone line (modular wire) wattage capacity

Discussion in 'General Electronics Discussion' started by vassock, Dec 22, 2015.

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  1. vassock

    vassock

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    Nov 30, 2015
    What is the power capacity of a 28 AWG phone line-type modular wire? Can it handle 200 milliamps at 12 volts, like the power requirement of a simple car backup camera?
     
  2. AnalogKid

    AnalogKid

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    769
    Jun 10, 2015
    Yes. 28 ga. wire has about 66 ohms of resistance per thousand feet, so a 10 foot long wire pair would have a total resistance of approx. 1.3 ohms. At 200 mA that's a voltage drop of about 1/4 volt. Not great, but the camera should be able to run on that. If you have an extra pair and can run two in parallel, that would be better.

    ak
     
  3. Minder

    Minder

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    Apr 24, 2015
    The NEC ampacity rating for 28 AWG is 800ma.
    M.
     
  4. vassock

    vassock

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    Nov 30, 2015
    Do these wires cause electrical fires if the limits are exceeded or if there is a short circuit or do they just melt inside the insulation without any risk of fire?
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Without a fuse all wire can burn if the source can supply enough current to do so. If it's being powered from an automobile battery I would definitely fuse it.
    Edit: A 1A fuse should work fine. You can buy In-Line fuse holders at your auto supply, Radio Shack ebay, etc.

    Chris
     
  6. GPG

    GPG

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    66
    Sep 18, 2015
    If you have reversing lights the run could be even shorter assuming an RF linked system
     
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