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Re: New saw purchase requires electrical upgrade

Grant Smith
Hi Doug,

Here's how I would think about this:

The breaker is there to prevent the wire between the breaker and plug from overheating, and therefore prevent a fire. Don't install a larger breaker on existing wire unless you are sure it meets code and is safe.

In most cases, a 20A breaker will have 12 AWG wire between it and the load. Know, however, that there are many caveats, exceptions, and limitations that come in to play in the electrical code. I am no electrician.

To keep it simple, DON'T install a 30A breaker on 12AWG wire.

Now, some comparisons to help you decide if you need to upgrade to 30A circuit:

When I set up shop, I installed a dozen or so 20A twist lock receptacles (L6-20R). That was nine years ago, and I have the following machines plugged in to those receptacles on 20A breakers (L6-20P). Some even share breakers if I don't expect simultaneous use.

Unisaw 3HP
Delta 15" planer 3HP
Oneida 3HP Dust Gorilla cyclone
Delta 1.5HP Drill press
Delta 1.5HP jointer
Rolair 5 HP 60 gallon air compressor (Leeson US made motor)

The Rolair compressor is a two stage 150 psi unit, and it kicks on when the pressure drops to 125 or so. If anything starts under load, it is an air compressor or dust collector. I was pretty sure I would have to install a 30A breaker when I brought it home. I decided to try it on a 20A breaker and sure enough, works fine on 55' of 12 AWG wire in conduit...with a 20A square D breaker.

Your mileage may vary, and given the sawstop's penchant to trip when there are power fluctuations, you might consider just adding the 30A circuit (with #10 wire, if it is a reasonably short run). The cost of upgrading in terms of materials is about equivalent to one trip due to a power issue.

I would add that I have a 3HP saw, cut lots of thick 2" plus slabs and similar materials and have never once thought the saw was under powered. No bogging down, no loss of power. I'd love to have a Sawstop for the peace of mind, but not sure I would go 5HP as a hobbyist. Do what makes sense for you though.


Grant in Iowa

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