Advantage to 230v single phase vs 115v?

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Aaron_W

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I have a lathe with a 1-1/2hp motor which can be wired as 115v 17 amps, or 230v 8.5 amps. It came wired for 115v.

I'm going to get some 230v outlets installed, and just wondering if there is any reason why I would want to add an outlet for the lathe and rewire it for 230v.

Understand many advocate for 3 phase which has some advantages, but not sure what benefit there would be to single phase 230v power. I know less amps, but does that justify the expense of a new outlet and the work involved in re-wiring the motor when it is serviceable on a standard 115v 20 amp circuit?
 
Yep, you are still just barely OK for 110. Don't put anything else on that circuit when the lathe is running.

If you're re wiring anyway, I'd put in a 220 circuit or two. Gives you future additional capacity. A 220 circuit is real nice in a shop. lets you run mills and lathes with a VFD, allows welders, plasma cutters, more.
 
The maximum sustained output on a 20 amp circuit is 18 amps. The maximum load on 12 gauge wire is 20 amps. By going to 220 volts the load on each wire is halved. Thus you can use 12 gauge wire on a 20 amp circuit with not only no fear of overloading, but you can also have multiple outlets or machines on the same circuit, rather than having a dedicated circuit for each machine.

I have a number of single phase machines in the shop that can run on either 120 volts or 220 volts. I have them wired for 220. It's easier and less expensive to run, and terminate 12 gauge wire than to use 10 gauge wire.
 
For the same wire gauge, higher voltage means less current, which means less voltage drop and more power from the motor. Possible advantage on a longer run.
 
Ok, so if a new outlet is required there does seem to be some benefit. I only have one 115v outlet at this time and need to add a 230v outlet for the mill. I was thinking about adding at least one more 230v and a couple more of 115v outlets. I just wasn't sure if it was worth the trouble to re-wire to 230v since it works as is.
 
If you ever decide to buy a VFD for the mill or your lathe, you'll be able to use one with single phase input and 3 phase output at 220V.
 
All in all, the prior posts cover the salient points very well. I throw in my two cents worth as an Electrical Engineer just to verify what they told you is so. Go to the web site:
for a longer story about the same subject, 120 vs 240 volts. Beside current there are a couple of finer points that cannot be covered here. And just good reading if you are curious about electricity. Go look it up, it's really a small book. The details of what you're asking start on page 8. But it's all good reading.
Bill Hudson​
 
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The mill is 3 phase so I have already bought a VFD for it. Now I just need to line up an electrician to do the 230v outlets. The thought was to go with one or two 30 amp in the shop (the VFD can be used with a 20 amp, but recommends 30 amp) to cover potential future needs.

A little more upfront cost, but cheaper than bringing an electrician out in the future to an upgrade. I was going to add a 40 amp outlet outside under the carport to allow the use of a welder that I don't have yet, but 40 amps seems to cover any of the welders on my list.

The main question was to answer one or two 230v outlets in the shop, and it appears 2 is the better answer.

Bill thank you, it is late so I just glanced through the document you linked but it looks very thorough and actually readable. I more or less get 115v, but 230v still has some mysteries for me.
 
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