220V electrical questions

[Doug W Swanson]

Hey all,

I'm in the process of building a workshop in my basement.

Currently I have a 1950's Delta Homecraft table saw that was my grandpa's. At some point in the near future I would like to upgrade my table saw to a cabinet style saw. To be prepared for the switch, I want to put in a 230V receptacle now while the walls are still accessible.

The receptacle will be about 35ft from the disconnect I am going to use. What size wire do I need?

Since I don't have a saw yet, anything else I can do now in preparation for the future?

One more thing, my PSI dust collector is currently 115V. It's a 2hp motor that draws 18 amps. I was planning on putting this on it's own 20a/115v circuit but should I switch it over to 230v as well?

Thanks!
Doug

[Bryan Wellman]

The amperage of a 220v cabinet saw will be a question for the guys who have one..... I would assume any that you are going to find will be below 30 Amps, thus letting you run #10 wire. As far as a recepticle, I would wait till you purchase a saw......just pull the wire, set a box and cap the wires for now.

Now....the 18A DC. Breakers are rated to handle 80% of the stated load constantly. Thus, a 20A breaker will hold 16A constantly. A DC would be a fairly static load, thus I would recommend #10 wire on a 30A breaker/outlet. You could probably get by with #12 wire (it is rated for 20A) on a 25A breaker, but you'd have to find out what local code dictates. I would personnally switch it to 240v which would allow you to run 12's since it would only be 9A/leg at 240v.

[Tom Veatch]

If you're going 240v, most any home/hobby woodworking equipment up to 3HP can be handled quite well with a 20amp circuit. That's assuming there's nothing else running simultaneously on the same circuit. Over 3HP and you should go up to a 30amp circuit. You are talking about one-way runs on the order of 35 feet, so 12ga on the 20amp and 10ga on the 30amp circuits should be fine.

Your 18amp DC is running on 120v. If you go to 240 with that device - assuming it's a dual voltage motor - it will only be drawing 9amps. No problem whatsoever on a 20 amp circuit. Note, again, that assumes there's nothing else running simultaneously on that circuit.

It certainly won't hurt anything to run 30amp/10ga circuits, especially if you anticipate installing 5HP machines, but it's a waste of time and money if you don't have and don't expect to run woodworking machines greater than 3HP. But, if you do, and are going with plug and cord connections, be sure to install 30amp receptacles, NEMA 6-30 in the straight blade or locking configuration. With 20 amp circuits, use 15 or 20 amp receptacles. 15 amp receptacles on a 20 amp circuit are acceptable to code if there is more than one outlet on the circuit. A regular old run of the mill 15amp duplex receptacle counts as two outlets.

My 3HP cabinet saw has a dataplate FLA (Full Load Amperage) of 14amps. Rarely is it fully loaded so it seldom draws that much current. The 240v/20amp dedicated circuit that it's been running on for about 8 years has never tripped - nor do I expect that it ever will unless the circuit develops a fault.

You needn't be concerned about the startup surge of this type of equipment. Woodworking equipment, saws, planers, jointers, etc., are all easy starting machines. The start surge is so short in duration that the normal circuit breakers you find in residential installations are quite capable of handling it. Now, if you had a fully loaded conveyor belt that you had to start from a standstill, that would be a different situation. Probably the hardest starting machine you are likely to see in a home/hobby workshop is an aircompressor or dust collector that has to bring a heavy impeller wheel up to speed. It's conceivable that they may require an upsized circuit. Mine are on 30amp/10g circuits, but they are 3.5 and 5HP machines whose FLA's call for greater than 20amp circuits, anyway.

Prudence requires that you verify this and any other electrical advice you receive on this or any other internet forum with a licensed electrician in your local jurisdiction.

[Chris Friesen]

Most 3HP cabinet saws will be fine with #12 wire, which is rated for 20A on a general purpose circuit. (Most of the saws I've seen actually come with a 15A plug, which is fine since it will fit into a 20A receptacle.) If you want to play it extra safe, you could use #10 wire and a 30A breaker but then you might have to put a new plug on the saw.

As for the dust collector, I'd suggest switching it to 240V. That way it only draws 9A or so, which would mean you could use #14 or #12 wire instead of being forced to use #10. It also spreads the loads over both legs of your electrical supply, making it less likely to dim the lights in the house.

I wired all my 240V woodworking tool circuits with #12. I have a 3HP tablesaw and 3HP planer, along with smaller motors on other tools. They're all fine with 20A breakers....haven't tripped any yet.

[Jeff Sudmeier]

I have two 20amp 220v circuits in my shop and I will be adding a 30amp soon for a bandsaw.

I run my planer, jointer and table saw off of one 20amp 220v circuit and the dust collector is run off the other.

The 20 amp circuits are 12ga wire and the 30amp will be 10.

[Doug W Swanson]

Thanks for the advice.

For the DC, I will probably just switch it over to 240 and run it that way. I did some more digging in the electrical system on my house and there is a 240v junction box about 20 ft away (from a long gone electric water heater) so I can just tap into that.

For the TS, since I am not a pro woodworker, I can't imagine ever needing more than a 3hp TS. I will just run some #12 from an unused disconnect at the panel to the j-box by the location of the saw. Then once I do upgrade, the hard part is done.

Thanks again!
Doug

PS I'll post some pictures when I'm done....