Circuits for tools, eh?

[Roger Tulk]

As I've mentioned before, I do my woodworking in the driveway. My power comes from an outlet on the porch which is on the same circuit as three quarters of the basement. Usually this isn't a problem, as I run only one tool at a time, but I've tripped the circuit breaker a couple of times when I've tried to run my shop vac attached to the bandsaw or whe I overload the table saw. As it is, the lights all dim for a second when I turn on the bandsaw. I would like to be able to connect the vacuum to the primitive dust removal system the previous owner put on the bandsaw, as I end up with dust drifts about my feet when I do a lot of cutting.

Now, I ran into an old friend and licensed electrician a week or so ago, and had him come to take a look at installing a couple of outlets on the side of the house, on separate circuits, one circuit per dual outlet. As an afterthought, I asked him if he could make one of the outlets a 20 amp circuit, which would allow me to run the vac and the bandsaw at the same time. He said it wouldn't be a problem, but as I know little about house circuitry, I am wondering if there is anything fundamentally wrong with having a 20 amp circuit for my tools. I'm thinking there isn't, as I run stuff that uses a lot less than 15 amps on a 15 amp circuit all the time, and the only comment my friend made was that we would use 12 gauge wire for that one. I will discuss it with him again, but can someone lay my fears to rest?

[Charles Hans]

There will be no problem Rodger, 12ga wire for a 20 amp circuit it what is required and you will have no dimming of the lights, Go for it.

[Jason Beam]

What Charles said. It's a common thing to think that more amps means more power but it isn't quite the way some people think.

Think of the circuit like you would a river. It runs at a certain speed, ok? The water flows by at the same rate all the time, but occasionally it floods because there's just too much water. Then someone comes along and makes that river wider and deeper to handle more water flow and address the lack of capacity in the river. Now all the water still flows by at the same speed, it just has more capacity. So if you had a mill that used a water wheel it would run at the exact same speed as it did before, and since you didn't change the water wheel any, it won't even know there's more water in the river - it only uses what it needs (the size of the paddles on the water wheel, essentially).

This is essentially how it works with electricity. A device only pulls the amps it needs unless there's a problem. The size of the circuit is only the maximum amperage it's designed to deliver at any given time and the breakers trip to protect that circuit when it goes over that amount (i.e. if there's a flood).

[Roger Tulk]

Thanks, guys. My concern was that perhaps a 20 amp circuit might not trip the breaker before there's a problem. Guess I'll sleep soundly now.

[Vaughn McMillan]

Thanks, guys. My concern was that perhaps a 20 amp circuit might not trip the breaker before there's a problem. Guess I'll sleep soundly now.

The only time the breaker will trip will be when you are running more than 20 amps on that circuit. From the sounds of things, that won't be happening.

Sweet dreams.

[Charlie Plesums]

If the lights dim, you are hurting your motors. Dim lights mean low voltage. Motors like high voltage.

The difference in price between a 15 amp circuit and a 20 amp is so small, I wouldn't consider putting in a 15 amp circuit any more. Go for it!

[Roger Tulk]

Heck. I'll sk him for two 20 amp circuits.

[Bruce Haugen]

If you are running any of your higher powered machines on an extension cord, I'd recommend getting or making a 12-ga. cord. I ran a true 1.5 hp tablesaw (actually, a 15 amp Baldor motor) off an extension cord and it was always tripping the breaker. After I learned that cord was only 16 ga., I made a 12-ga multistrand extension cord just long enough to reach the saw and the problem went away. It hasn't tripped even once since then.