I am looking to run electricity to my shed and I am unsure of what size wire and breaker I need.

My main panel will be about 100ft away from my shed. My shed is 12X20 and I want to install 6-8 4ft 4 bulb fluorescent/LED lights, LED flood lights and about 8-10 receptacles. Two of the 4ft lights will be outside under the lean-to of my shed along with 2 of the receptacles.

I will be using table, miter, scroll and circular saws, a router, an air compressor, a shop vac, a grinder, an AC window unit, a shop fan/blower and plan on adding a CNC router, a dust collection system, a 60-80 gallon air compressor and possibly a welding machine on the exterior.

Of course I will not be using all these at the same time but I would rather do it right the first time.

  • What size is your existing electrical service? Commented Jun 24, 2020 at 0:13
  • 1
    Will any resident ever own an electric vehicle? Commented Jun 24, 2020 at 1:05
  • You're not looking to add "a breaker" - you're looking for a whole sub-panel! Keep in mind that you may need to supply 240v for the welder and possibly the CNC router, so you'll need extra space in the panel. As both Harper and TPE always say, it's cheaper to buy a lot of spaces now and not need 'em than to replace the panel later when you do need 'em.
    – FreeMan
    Commented Jun 24, 2020 at 14:13
  • Also, I know that "shopping recommendation" questions are off-topic (you didn't ask one), but I've got to say that I recently installed some LED shop lights from a store that gets their Freight at the Harbor ;). They're plug-in (not hard wired), but they are fantastically bright at 5000 lumens each and I highly recommend them! They seem to have a slight flicker for the first minute or two when they're turned on, but it does go away. I don't know if they're rated for outdoor installation, though, so be aware of that.
    – FreeMan
    Commented Jun 24, 2020 at 14:20
  • @ThreePhaseEel I have none in my shed at the moment. I am planning to put some soon. This is why I asked. I believe my main panel on the outside of my house is 200 AMP. Commented Jun 24, 2020 at 17:13

1 Answer 1


You will not be using everything all at the same time. So I would look at the nameplate Full Load Amps of your largest load, probably the table saw, plus any other things that might be running at the same time, such as the dust collector, lights and if the compressor is on a demand pressure switch, add that too because it might come one without you turning it on. Then add another 25% for good measure.

  • Ok. I will look at all my tools and find that out. Thanks Commented Jun 24, 2020 at 17:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.