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Is Bigger better?

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  • Is Bigger better?

    Hey all!

    I have a theorical question... say you take a 12g wire... what is the longest run you can roll out... feed it a steady 120v and the... at the other end you would put a meter... after how long would you start to see a degradation on the meter?

    How about running 12v through a 12g wire? how long would it be?

    Thanks!

  • #2
    Re: Is Bigger better?

    Well your question is a little bit bogus because you left out one main factor. You have to tell us what is the current draw on the wire that is as long as you mention. The higher the current demand on the wire and the longer the wire is, the more voltage drop you would read at the other end. There is as math formula to calculate the voltage drop on any size wire, but if you put "0" in as a current draw the answer is then 0. But in the real world the wire does have some resistance so there would be a small voltage drop just in the length of the wire without any load other than the small load of the meter that does the measuring. Now once you drop the voltage to 12v and you pull any signifigant load at a long wire length, the size of your wire has to be much bigger than with 120vac. Again, you must know the current you are drawing on the wire and the size wire you are using, then you can use the math formula to calculate your volatge drop. The NEC will allow up to 3% Vdrop under their rules. Using 12 volts is not an efficient way to transfer voltage over long wire lengths.

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    • #3
      Re: Is Bigger better?

      A simplier statement would be "Load dictates length" for a cetain size of conductors, where load is in amperes (current).

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      • #4
        Re: Is Bigger better?

        It's all in the AMPS.

        When you are talking 12V, for example landscape lighting....it takes a lot more amps to deliver a certain WATTS to a bulb. For example, a 120 watt bulb takes 1 amp from a 120 volt circuit, but requires 10 amps from a 12 volt circuit. It is the AMPS X ( wire resistance) that causes the voltage to drop over length.


        Consider the utility transmission lines. They need to deliver MILLIONS of kilowatts, so the VOLTAGE is in the tens of thousands, even millions, so that the DROP will not be too large. It is relatively easy to jump the VOLTS up, then drop it back down on your street.

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