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110v/220v single phase,,,,whats the difference???

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  • 110v/220v single phase,,,,whats the difference???

    whats the difference?
    I am specifically speaking of motors under 1hp.
    My little lathe is 1/2hp, it can be either 110v or 220v. what is there to gain to go to the trouble to rewire a plug and circuit to support this on 220v?
    at the end of the day,,,it is still 1/2hp,
    it is still single phase,
    it is still 60hz.
    what is the gain?

    same for my little mill, it is 110v 3/4hp?
    what is to gain?

    and my table saw, 1hp at 110v?
    what to gain?

    please no discussions on going over 1hp.
    when you get into over 1hp, I get it, please dont go there.
    I am referring to that under 1hp.
    Last edited by Ringo; 05-01-2020, 09:39 PM.

  • #2
    Only thing that I can see is, maybe you have to keep the amps down on that circuit for some reason. 220 lets you do that (smaller wire) Otherwise under 2HP I go 110V. My air compressor can be either way but I leave it setup on 110V because its more portable that way.
    25 miles north of Buffalo NY, USA


    • #3
      You gain decreased voltage drop on heavy loads - which makes the motor work harder - which drops voltage even more - which make the motor work harder...

      The same reason the the electrical grid uses extremely high voltage to transmit power over long distances.


      • #4
        Interchangeability could be a big factor. If the shop is wired with a bunch of 220v outlets for the over 1hp machines the under 1hp machines can utilize the same style outlets. Easier if everything is the same.


        • #5
          The above posts pretty much say it all.

          To put in in practical terms... a 1/2 HP motor will draw 3.5 amps (when running) on 110V, and 1.75 amps on 220V. A 15 amp circuit on 220 can handle twice the number of motors without having to upgrade the wiring and circuit breakers. You could have twice as many lathes. It's different if you are installing a welder or a device with a multiple HP motor.

          But having said that, if you already have 110 wired to the place you want to use it, there is no advantage to installing 220 just for that particular use.
          At the end of the project, there is a profound difference between spare parts and left over parts.

          Location: SF East Bay.


          • #6
            The technical part has been stated- less current flowing means less voltage drop in the wiring, which is a good thing. You could find that your motor comes up to speed quicker on 220- that was important to me for a table saw at one point.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


            • #7
              In practical terms, at a half HP, for the lathe and mill, essentially nothing except the trouble to rewire to get 220V everywhere you need it.

              People can argue the fine details until the cows milk themselves, but really there is nothing special. If you have 120V, leave it and use it. If you have 240V, use that.

              The table saw, well maybe. The saw MIGHT jam less, it MIGHT power through a bit better, and it will probably come up to speed faster.

              If the tools are all out in a shed/barn 200feet from the house, on the same service, go 240V, you will get better performance at least from the saw. If everything is in the house/garage, with the service close by, then I'd likely not bother unless maybe the saw was causing trouble jamming.
              CNC machines only go through the motions


              • #8
                If you are running this stuff in a separate shop a fair distance from the house and the wire from the house is not all that big a gauge there is a very real advantage to balancing the load across the two single phase sides.

                Having said that 3.5 amps for a 1/2 HP motor is not a big deal unless the wire to the shop is questionable.

                For myself I prefer to wire the motor for 220v and wire the shop accordingly for motors of 1hp and more.
                Chilliwack BC, Canada


                • #9
                  I always opt for the higher voltage when available. I don't trust old installed wiring. Connections can loosen. Amps cause heating at poor connections, heating leads to fires.

                  Fire sucks!


                  • #10
                    It has been said: smaller wire and/or less Voltage loss in those wires. But that's a tradeoff; you get more of one and less of the other or vice-versa. You can't have all of each. Smaller gauge wire = more Voltage drop while to get the lower Voltage drop you need to keep the larger gauge wire.

                    That being said, when I wired my shop I used 12 gauge for everything. It was available in 50 and 100 foot coils for a decent price. I guess I could have searched for 14 gauge and saved a few pennies, but it wouldn't have been much. Electricians will buy it 10,000 feet at a time and will save more so they have a reason to use smaller gauges when they can get away with it. That (the budget of electricians) probably explains the fact that many motors are available with changeable wiring for both Voltages. In my case, I ran both 115 and 230 Volt circuits with the same 12 gauge cable. I didn't save any dollars or pennies, but I guess I get a bit more Voltage at the machines that way so things are a bit more efficient and a bit more powerful.
                    Paul A.
                    SE Texas

                    And if you look REAL close at an analog signal,
                    You will find that it has discrete steps.


                    • #11
                      You can run more 240v motors on your shop power drop, than you can 120v motors at the same time, if that is a consideration; most of us likely wouldn't notice.

                      I would wire my 120/240 motors for 240v if I had the outlets because they will start easier and run cooler, and hopefully last longer.


                      • #12
                        what is the smallest 220v circuit breaker??


                        • #13
                          Originally posted by Ringo View Post
                          what is the smallest 220v circuit breaker??
                          For "home" usage in US, it is likely that there is no breaker under 15A, because the smallest branch circuit conductor recognized by the NEC is 14 Ga, which is rated 15A in copper.

                          For the US, there is no difference between 120V and 240V, since the voltage to ground is within the same classification of "under 300V".
                          CNC machines only go through the motions


                          • #14
                            well then if 15 or 20 amp is the smallest 220v breaker, you could run your 1/2hp lathe, your 3/4hp mill, plus a table saw on that one breaker circuit???


                            • #15
                              Ringo: Home depot has them down to .5 amps. HD has a huge range of them available, up to 225amps. You can get 5, 10, 15 and 20 amps as well as a lot more. The breaker protects the wiring, so if the wiring can handle the load from a mill, lathe and table saw, then there is no reason that you can't do it.

                              Last edited by danlb; 05-02-2020, 02:30 PM.
                              At the end of the project, there is a profound difference between spare parts and left over parts.

                              Location: SF East Bay.