What gauge wire?

Discussion in 'General Electronics Chat' started by Dan R Braucht, May 21, 2015.

  1. Dan R Braucht

    Thread Starter New Member

    May 21, 2015
    I'm fabricating a massive Live-edge, wood slab milling machine. One of my motors that will move my cutting head is gear motor, 12v DC. The motor is stamped 1/4 hp and the max. amps (23). There is an in-line protector (10 amp). My remote control box has speed control & directional switch . . . . . .From control box to the motor is 30 ft.
    . . . . .What gauge wire must I run ? There will be very little load on this motor, as it is just repositioning the head after each pass. It has a 60:1 gear ratio (41 rpm max.)
    Any help would be greatly appreciated.
    thanks, Dan
  2. MaxHeadRoom


    Jul 18, 2013
    23amps is roughly 1/3hp, but the ampacity of 12g is 20amps and 10g is 30 amps, you most likely do not need any more than 12g.
    What is the nature of the 10amp protector?
    14g carries 15amps.
  3. Dan R Braucht

    Thread Starter New Member

    May 21, 2015
    The 10A protector was installed by the refurbisher. I'm going to try 14g and see how it performs . . . thanks-so-much for the reply, Dan
    . . . .Dan R Braucht flickr photostream shows some of my recent Ideas . . . enjoy!
  4. MrAl

    Distinguished Member

    Jun 17, 2014
    Hi there,

    There are some rules of thumb that are applied at 120vac but they wont really apply directly for 12vdc. The difference is that the line voltage drop affects 12v ten times worse than with 120v.
    For example, if a line drops 0.5 volt at 120 volts that is about a 0.4 percent drop, but at 12 volts that would be a 4 percent drop, 10 times more.

    To figure out the voltage drop you can calculate the resistance of the wires and then use Ohms Law to calculate the voltage drop. The available power goes down with the square of the voltage ratio so for a 1v drop you'd loose about 16 percent power.
    The resistance goes up with the run length, so a longer wire will drop more voltage. If you state the run length from the source to the load we can calculate the resistance and the voltage drop at 10 amps.
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
  6. Dan R Braucht

    Thread Starter New Member

    May 21, 2015
    shortbus likes this.