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Both my table saw and my jointer have the option to be run as either 110, or 220. I am wondering (assuming I have my choice of plugin's in a shop) is one better than the other. I've heard that 220 will actually use less energy and be easier on the motor.

If I can convert to 220, should I? Is it more efficient and easier on the electric motors?

  • Where are you in the world? In the UK I would use 220 (or 240) at home, but may be forced to use 110 on a building site due to outdated health and safety rules. – Ian Ringrose Jun 17 '15 at 14:14
  • @IanRingrose US. Like many things we're backwards and 110 is our default power for everything, 220 is special wiring. – bowlturner Jun 17 '15 at 14:20
  • Unlike many things in the US, I don't think of the usage of 110 as the default voltage to be backwards, just history. – Ian Ringrose Jun 17 '15 at 14:52
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I am wondering (assuming I have my choice of plugin's in a shop) is one better than the other.

It all comes down to wattage. P = IR; i.e., Power (Watts) = Amps * Voltage. If a given tool draws 14A on a 120V circuit, the same tool will draw 7A on a 240V circuit. The more amps you send through a wire, the thicker (higher gauge) the wire you need, as touched upon by Steven. Your tool will draw the same wattage whether it's wired for 120V or 240V.

Let me run through the rest of your question's components before coming back to the first part of your question.

I've heard that 220 will actually use less energy...

The reason we use high voltage transmission lines for power distribution is that power is transmitted more efficiently over long distances at high voltage. For a given amount of power, you'll lose a certain percentage due to the resistance in the line itself. As current (amperage) increases, the resistance increases (resulting in a voltage drop--giving you an overall power loss), but if we decrease the current and increase the voltage, we can transmit the same amount of power with less line loss.

That said, for all practical purposes, if you're running 1-phase power in a hobby shop or even a small production shop, the line losses from your breaker box to the tool will be insignificant and it won't make a noticeable difference whether you're running 120V (110V) or 240V (220V). Your electric bill will be the same either way.

One might be inclined to think that you should be using less energy because you're drawing fewer amps, but you're actually drawing power on one hot 120V leg and returning it on another hot 120V leg which is 180 degrees of phase with the first. The phase offset effectively doubles the voltage differential between the source and return, giving you 240V. A convenient (though technically incorrect) way to think about it in terms of what you see at your electric meter is that you're "drawing" that many amps from two 120V legs.

...and be easier on the motor.

I'm not so sure about this, but I doubt it. Maybe this is a misunderstanding of the difference between differences between different types of motors, or single-phase vs. 3-phase motors.

A 3-phase motor is simpler in design than a 1-phase motor because, as Steven mentioned in his answer, the 3-phase motor does not require a separate starter coil. 3-phase motors are also considered inherently more reliable by design.

If I can convert to 220, should I? Is it more efficient and easier on the electric motors?

If all your existing equipment does what you need it to do on 120V and you don't need any other equipment, there isn't really a compelling reason to install 240V circuits and switch your equipment over. However, if you plan on upgrading your table saw from a 1.5hp motor to a 3hp motor, for example, you will need to run it on a 240V circuit.

When you're shopping for tools, you'll often see that a tool can be wired to run on either 120V or 240V. If it's advertised as being 120V-capable, be sure to also check the amperage.

Usually for 120V, you need a 15A or 20A circuit. The maximum load allowed by code on a 20A circuit is actually 16A. Usually if the tool draws more than 16A, a 240V circuit is recommended since 120V circuits greater than 20A are not commonly installed in residential construction (at least, in the US). Upgrading a circuit from 20A to 30A isn't as simple as swapping out a breaker and receptacle, because to carry more amps, you also need a thicker wire.

Getting back to tool and voltage options--some tools, such as a bandsaw I was looking at a while back, are advertised as 120V/240V. However, in the case of that bandsaw, the tool actually required a 30A circuit in order to run on 120V. If you ever look at a tool like this and have to install a new circuit anyway, it makes more sense to go with the 240V circuit because it's more common to have a tool that's certified to run on 240V than one that's certified to run on a 30A, 120V circuit.

  • My table saw came set up to run on 120, but it says I can get a new plug, and change something (have to look in the book) and it will then run on 240. I've always just plugged in in a regular socket. – bowlturner Jun 9 '15 at 15:40
  • Yes, usually there's a removable plate near the power switch that gives you access to the wiring, and the switchover is pretty simple and inexpensive. Installing a 240V circuit isn't incredibly expensive, but in my area of the US it runs around $200-$300 for a fairly short run if you hire an electrician. I think technically it should be safe to convert an existing circuit from 120V to 240V, but code might only allow one 240V receptacle per circuit. – rob Jun 9 '15 at 15:52
  • I've raised a version of the code question over on Home Improvement. – keshlam Aug 30 '15 at 7:37
  • Thx @rob for explaining this so good. I thought about asking a similar question about the benefits/drawback of European circuits. In my workshop there are a lot 230 V outlets and three 400 V outlets. I recently bought a few machines and made it a low priority to get the 400 V versions as they are said to be better, at what exactly I don't know, even after some reading into the issue. – Stoppal May 31 '16 at 11:16
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220V devices run at lower currents since voltage and current are inversely related, and as such, require smaller conductors. Smaller conductors in wire is cheaper, so installing a circuit to support 240V/15amp is cheaper than 120V/30amp.

There are efficiency improvements in motors when running at 240V, and even more so in running 3-phase power. 3 phase motors don't require a secondary winding to help start the motor, so they can be a bit simpler in constructions. However 3 phase power is typically only available in commercial or industrial environments.

If you already have it setup for 120V, then there probably isn't much benefit in converting for the fun of it, but if you were installing new, 220V would be preferable.

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Being an old fogey, I have a lot of experience with 110 vs. 220 in a shop environment, both commercial and personal. My primary tool for years (early 60's on) was a radial arm (all 10" Craftsman's, my current one is circa 1958). Having run it on both 110 and 220, the biggest difference is power recovery. Not only is the start-up much faster, but any cut's through knots or tough grains will be a lot smoother with very little lag through knots, etc. Yes, it is a fact there is no power difference between the two voltages at the motor when running static. The 220 volt saw just tends to have smoother and more consistent cuts, especially in tougher materials. Of course a good Sharp, negative angle blade is a must as well with any voltage, but the advantage goes to more voltage.

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This question about voltage gets asked a lot. Going to 240 V does not change the power drawn by the saw. It might change the power to the blade, which is very different. In my case I have a 2 hp General TS that was wired for 110. I had it plugged into 110 but the 15 amp wiring in my shop really could not handle it. So... I was going to have to pay for a new circuit and wires. So I Went for a 240 V 30 amp circuit (same price). Now if I ever go for a 3hp cabinet saw, I am ready. The saw now starts immediately and the lights don't dim. I think the no load blade speed is faster. So, if you have very heavy wires, a 2hp motor can run on 110. But, as in my case, maybe not so much. Cutting 2" thick maple just got a whole lot easier.

  • Nice answer and welcome to the site! – drs Aug 29 '15 at 16:44
  • I'm not sure I follow the comment, "It might change the power to the blade, which is very different." Would you please elaborate? – rob Aug 30 '15 at 2:40
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Power to the blade has to do with motor efficiency. Motors are carefully designed to be efficient as possible. But, if you start asking for more amps than your circuit can provide, the voltage to the motor drops below the design point, efficiency goes down, and power to the blade drops. This can result in stalling ( very bad for the motor ) or breakers tripping. Because of this, if you have 14 gauge wiring, you might actually get better cutting with a 1.5 hp motor than with a 2.0. I hope this makes this clear. BTW I tried cutting some 2" hard maple on my new setup, and thought the piece had slipped in the mitre gauge and was not being cut ... But it was going through the saw like it was nothing. Pretty cool.

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