110V or 220V

[Marc Schneider]

I'm considering the purchase of a new Table Saw for my workshop. I wired my workshop with three dedicated 220V outlets, one of which is currently in use by my dust collection system. I also have several 110V circuits.

The saw I'm considering comes wired for 110v, but can be rewired for 220V. What advantage if any is there to running the saw off of a 220V circuit? If I use a 220V circuit is there really any advantage over a dedicated 110v circuit? The saw is rated at 1 3/4 HP and draws 14A at 110V and 7A at 220V.

The dedicate 110V circuit I would use is a 20A circuit (as is the 220V circuit).

[Dan Friedrichs]

Depending on what size of wire you used to wire the dedicated 110V outlets, you may find that the saw comes up to full speed slightly faster when wired for 220V. And by "slightly faster", we're talking fractions of a second, at most. Since you have a dedicated 110V outlet, and the saw is already wired for 110, I'd just use that - in practice, you won't see any real advantage to 220.

[George Bregar]

Only reason to rewire for 220V is that you might trip the 110V 20A breaker if you stall the saw.

[glenn bradley]

I have run my saw at 120v and 240v, each a couple times. In my last electrical re-work I ended up with a 120v /20a nearby and so switched back (again). I experience no difference in performance at either voltage.

You will read posts here and there by people who were running their saw at 120v, along with the lights, a fan and their stereo all on the same 14 gauge wired circuit. Amazingly enough when they switched to a properly provisioned 240v circuit the performance jumped drastically ;-) They would have experienced the same thing if they had installed a properly provisioned, dedicated 120v circuit.

Having a tool that will operate correctly at both voltages gives you some flexibility so I would take advantage of it in the way that best serves your setup.

[Gerald Senburn]

One of the better webpages I've seen on the subject. Basically, the answer is for almost everyone, you're better off leaving it at 120V.

[Barry Lyndon]

Wow, this thread kinda just blew my mind. I always assumed there was a definite advantage to using 220, no question about it. Guess not. I actually just added a sub panel in my shop and have been in the process of adding some new outlets around the shop for the last couple days. I was planning on putting a few 220 outlets around the shop and re-wiring my bandsaw to use 220 instead of 110 but now I guess I'll skip that. I may even skip putting in the 220 receptacles too and just worry about it if/when I ever get a tool that only uses 220. Interesting thread for me...

[Van Huskey]

I do it cause it makes my machines look more powerful... that is all.

[Chip Lindley]

Wow, this thread kinda just blew my mind. I always assumed there was a definite advantage to using 220, no question about it. Guess not. I actually just added a sub panel in my shop and have been in the process of adding some new outlets around the shop for the last couple days. I was planning on putting a few 220 outlets around the shop and re-wiring my bandsaw to use 220 instead of 110 but now I guess I'll skip that. I may even skip putting in the 220 receptacles too and just worry about it if/when I ever get a tool that only uses 220. Interesting thread for me...

I won't belabor this thread with all the pros of 230V circuits in the shop. Bottom line: As long as your machines run well on 110V, all is good. But the day may soon come when horsepower outstrips the capacity of 110V. Early on, I found the need for 230V when I bought my first real machine in the mid '80s; a Rockwell RC33 2hp 12a 230v planer. I had a 100A branch box installed in my garage, and never looked back.

As amperage increases, 110v wiring cost increases big time. A 20A, 110V circuit specs 10ga wiring. That same wiring would be rated for 30A (or a 5hp motor) at 230V. Much more bang for your buck! Think ahead--Think 230V!

I do it cause it makes my machines look more powerful... that is all.

Yeah, Van, I really have a thing for those Hubbell L6-30 TwistLocks! Wayy Cool!

HBL2621-2.jpg

[Don Bullock]

Wow, this thread kinda just blew my mind. I always assumed there was a definite advantage to using 220, no question about it. Guess not. I actually just added a sub panel in my shop and have been in the process of adding some new outlets around the shop for the last couple days. ...I may even skip putting in the 220 receptacles too and just worry about it if/when I ever get a tool that only uses 220. Interesting thread for me...

Barry, you may find a need for the 220 receptacles and regret not adding them in now. When I had my shop built I made sure that it had plenty of 220 receptacles to start with and I'm glad that I did. Besides, those twist lock plugs do look great.

[Mike Henderson]

As others have said, technically there's no difference between running at 120V and 240V. But the rule of thumb I use is any motor greater than 2HP gets run on 240V.

Mike

[Dave MacArthur]

This comes up all the time, and there are some good threads out there on this. IMO the single biggest reason to go 230V is that it reduces your Amperage draw. And most shops sub panels are amperage limited-- a lot of folks will just run a feeder gauge big enough for 60A.

Additionally, proper gauge wiring for a motor IAW the NEC is usually significantly more conservative than many folks assume. While the motor may run OK and not trip the CB, you're supposed to use amps from the NEC tables, not the motor nameplate, and it's higher in the NEC. Then you have to use continuous duty upscale the amps for that...
Here's my thread on motor/NEC calculations, you'll be able to figure out the 115V 1.75 HP numbers from there...
The NEC gives 1.5 and 2HP full load current of 20 and 24A at 115V, so if we have 1.75 HP on the motor nameplate, and interpolate the required NEC FLC as 22A, then we must multiply by 125% for continuous duty (required on a motor circuit), we get 27.5A as the current your wire is required to carry. That means 10 ga wire is required, as the termination criteria is 60C table for NM cable, 75C max with any cable, and 12 AWG will only carry 25A in the required 60C or 75C column for heat-sink termination criteria. It will flow 30A on the run if your line is THHN, but you have to use the more conservative of termination criteria or wire ampacity. Therefore, your 1.75HP should be run on a 10ga wire circuit at 115V.
On a 230V circuit, the FLC is 11A, *125% continuous duty = 13.75A, which you can run on a 14ga wire!
Now, if you have to run a 10AWG circuit to be able to run your saw at 115V, I submit to you that it's NOT the best way to go.

Sizing Wires and circuit breakers for 3HP and 5HP shop motor circuits

Bottom line, it's significantly easier to comply with the NEC for ampacity of wiring on motor circuits when using 230V, because your given gauge wire only has to run half the amps. And there is no downside.

[Aaron Berk]

I run 220v where ever possible, I'm limited on my amps from the main breaker, that's my reason for it.

The twist lock plugs come in real handy as a side benefit.

[Josiah Bartlett]

For a contractors saw I wouldn't bother since it makes it less portable, unless you never want to be able to use it offsite. I like 240 volts because it prevents my friends and neighbors from being able to borrow my tools unless they come to my shop to use them.

[Mike Cutler]

Mark

There is no realized difference that you will be able to quantify. I have a General International Hybrid saw. It also has a 1.75 hp dual voltage motor that came wired for 115. I just left it as is, even thought the 220 and 120 plugs are right next to each other in my shop. ( I have 220 and 120 on all the walls in my shop.)

The advantage of 220 is that eventually you will want bigger machines, more horsepower, and will exceed the capability of a 120 circuit ,thus having to install the 220 at a later date.
The current draw is the same. The only difference is that the total current draw is shared by two legs in a 220 circuit, each hot leg, and a common return. in a theoretical world world this means that each "Hot" conductor will be "cooler", but you'll never see it.

Rick Christopherson is a member here and has what I believe is the best web page for explaining electricity in the shop. Here is the link.

http://www.waterfront-woods.com/

[Mike Henderson]

Mark

...The current draw is the same. The only difference is that the total current draw is shared by two legs in a 220 circuit, each hot leg, and a common return. in a theoretical world world this means that each "Hot" conductor will be "cooler", but you'll never see it.

Rick Christopherson is a member here and has what I believe is the best web page for explaining electricity in the shop. Here is the link.

http://www.waterfront-woods.com/

I'm afraid that's not correct. When you run a 220V circuit, there are only two wires that carry the current and voltage. The neutral (or common) is not part of the circuit. The reason you have half the current in a 220V circuit (for the same load) is that power is voltage times current (when power factor is ignored) so when you double the voltage, you halve the current.

Mike