My main panel has been upgraded to 100 amps. I would like to add a subpanel in the garage which would supply:

  • 20 amp Mig welder running on 120 volts, but later upgrade to a larger Mig welder as i am experienced at welding.
  • Large jointer
  • Medium sized table saw, which is 120 volts and 12 amps
  • 4.5 hp portable shop vac
  • A sander
  • Branch circuits for good lighting, and 5 receptacles.

The main run from the 100 amp panel is 37 feet exactly, so what would be the ideal gauge and type of wire to use for feeding the sub-panel?

Is it a good idea to run the wire in metal conduit the whole span, since the feed goes though the basement ceiling and though a concrete wall in the most direct straight-line to the garage?.

I would like to do the job myself as I have seen the sloppy job the so called electrician did with the main panel, which passed hydro's inspection! I have taken and passed an electrical college course at my local college, I have an eye for detail and am a perfectionist.

  • This answer might be useful. This answer might also help, and This answer too.
    – Tester101
    Oct 16, 2013 at 10:16
  • 1
    If you've just upgraded from 60 to 100; and you still have the old panel, you can likely modify the old panel to work as a subpanel.
    – Tester101
    Oct 16, 2013 at 13:37

1 Answer 1


My answer is almost always the same when talking about garage subpanels.

  • 60 ampere double pole breaker in the main panel.
  • 6 AWG copper wire (x4) for a run less than 75ft., 4 AWG copper wire (x4) for runs less than 150ft.
  • 60 ampere panel with 60 ampere main breaker.

Unless you're running a whole bunch of stuff at once, a 60 amp panel should serve you well.

If you're running individual conductors, you'll definitely want to run it through conduit. If you're using a cable assembly, you'll probably only use conduit if you have to. For example, if you have to protect the cable from physical damage, or it will be underground.

  • 1
    @SteveK, L1 & L2 hot, neutral, and ground
    – mjohns
    Jul 26, 2015 at 21:17
  • Solid or Stranded?
    – JJS
    Nov 15, 2016 at 21:23
  • @JJS makes no difference.
    – Tester101
    Nov 15, 2016 at 23:20

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