120 vs 240

[djjsr]

I have a tablesaw that will run on either 120 or 240 volts. When I bought it a few years ago I just plugged it into the 120 wall outlet and I've been perfectly happy with it's performance.

I do have 240v readily available and I'm trying to understand why I think I should run it on 240. I have lots of breakers and wire so that's not an issue.

So, what's the advantage?

 

[VHF]

Running on 240V instead of 120V would cut the amp draw in half. This means less voltage drop, and thus less resistive losses (heating of the building wiring.)

This topic has come up before. I think the conclusion was that for most equipment that offers the ability to run on either voltage, the benefits of using 240V would be too small to measure. Better to keep the flexibility of being able to plug into any 120V outlet.

However, running your saw on 240V would mean the load would be balanced between the two incoming hot legs, so might cut down on the voltage drop you see, especially at start-up.

 

[Gary S]

On a motor small enough to be dual voltage 240/120, there is seldom any advantage either way. Use it the way you are unless you find a compelling reason to change it.

 

[Speedy Petey]

However, running your saw on 240V would mean the load would be balanced between the two incoming hot legs, so might cut down on the voltage drop you see, especially at start-up.

This is probably the biggest reason. It's not that it might cut down VD, it WILL cut it down.
VD @240V is 1/4 as severe as it is @ 120V.

 

[Falcon67]

240V motors use the same current but they work easier than a 120V motor. Next up is 3 phase, which work even easier.

 

[Alchymist]

240V motors use the same current but they work easier than a 120V motor. Next up is 3 phase, which work even easier.

Define "work easier", if you will?

 

[Larwyn]

I have been purty much convinced that it doesn't make much of any difference. But I changed over everything in my little wood shop that would allow it anyway. It was easy enough to do and cost very little in the way of supplies and sure didn't hurt anything. I like to think that a more balanced load on the source makes it worthwhile. In fact all my 120 volt outlets in the shop are marked with the breaker number and panel buss (L1 or L2) so I can try to help balance the load. There are three duplex outlets at each location, two 120 volt, one on each buss and a 240 which is of course on both. They are all 20 amp except for the single 50 amp welder outlet. It is likely a small thing but I am not very likely to be unnecessarily tripping the 60 amp main breaker because all the load was on one leg.

 

[Highbeam]

People will be less likely to borrow your table saw. If you ever need to use this tablesaw at a site with no power, you'll need a bigger genset.

Also, the 240 version will use half the current (amps) right? Falcon said it would be the same but the only thing constant is that wattage.

 

[Falcon67]

I tend to think of it like cylinders in an engine. 120 is a one lugger, 240 has the line phases 180 out, so it's more like a 2 cylinder.

1 hp = 745w. 3 hp @120 is 2235/120 = 18.6A. 3hp @240 is 2235/240 = 9.3A Current draw on the wire is less, same energy used.

 

[Alchymist]

I tend to think of it like cylinders in an engine. 120 is a one lugger, 240 has the line phases 180 out, so it's more like a 2 cylinder.

1 hp = 745w. 3 hp @120 is 2235/120 = 18.6A. 3hp @240 is 2235/240 = 9.3A Current draw on the wire is less, same energy used.

So how does it "work easier"?

 

[Norcal]

1 HP & smaller motors make more sense to run at 120V, as 120V receptacles are more prevalent, at 1 1/2 HP it gets iffy as under load it will not take much to trip a 20A circuit breaker, 2 HP is too much for a 20A 120V circuit.

 

[Motofixxer]

I switched mine over and it runs noticeably better. Doesn't bog down as easy and spins up from a stop faster. I like it better.