110 vs 220

[Mike Henderson]

That is just in the UK, a site transformer has a 240 volt primary, 110V secondary with each leg being 55 volts, no neutral.

I was just thinking - with no ground on the secondary, you would not get a shock to ground. You could only get shocked if you touched both wires and the potential is only 110V which is not as dangerous as the 240V.

Mike

[Rick Christopherson]

I was just thinking - with no ground on the secondary, you would not get a shock to ground. You could only get shocked if you touched both wires and the potential is only 110V which is not as dangerous as the 240V.

Mike

No. The transformer has a neutral bond so the ground is carried from the supply side. In other words, the "neutral" (incorrect usage in this case) of the primary is connected to the center-tap (correctly called the neutral) of the secondary.

[John K Jordan]

The reason for running an induction motor of greater than 1.5 hp on a 240 V circuit is...

One good reason to run a motor on 220 rather than 110 is the length of the run. Since the motor will pull 1/2 the current, you can run a given size wire further. In my very first little stand-alone shop (45 years ago) my radial arm saw was slow to start and lacked full power on 110. Without changing the underground wire, I switched the motor wiring to run on 220. MUCH better performance!

Another example is a pump my BIL had at a spring far from the house. The wiring was undersized for the load at that distance. He burned up three motors untill he switched to a 220v motor, using the same wiring. That pump motor ran for many years until they switched to a well.

JKJ

[Mike Henderson]

No. The transformer has a neutral bond so the ground is carried from the supply side. In other words, the "neutral" (incorrect usage in this case) of the primary is connected to the center-tap (correctly called the neutral) of the secondary.

Ah, okay, I understand. Thanks.

Mike

[Dennis Aspö]

The residential supply is 3 phase, not single phase like the UK or New Zealand. 230V for most items & 400V for the range.

Or in the workshop, 400V is pretty sweet, and 3ph motors are nice to work with. Only bad thing is the expense of 3ph cables, 39 euros for 10 meter extension cord
.

[Julie Moriarty]

One good reason to run a motor on 220 rather than 110 is the length of the run. Since the motor will pull 1/2 the current, you can run a given size wire further. In my very first little stand-alone shop (45 years ago) my radial arm saw was slow to start and lacked full power on 110. Without changing the underground wire, I switched the motor wiring to run on 220. MUCH better performance!

Another example is a pump my BIL had at a spring far from the house. The wiring was undersized for the load at that distance. He burned up three motors untill he switched to a 220v motor, using the same wiring. That pump motor ran for many years until they switched to a well.

JKJ

The initial installer didn't take into consideration voltage drop. Changing to a 240v motor was a nice work-around.

[Rod Sheridan]

Of course there is. A 120v 1hp motor has (approximately) 10a on 1 leg. A 240v 1hp motor has (approximately) 5a on each of two legs.

You are free to use any model that works for you, but there is nothing wrong with the one I like.

Completely incorrect.

In both cases there is only one circuit, and one current path.

At 120 volts there is 10 amperes in the wire, in both the neutral and the line, at 240 volts there is 5 amperes in line 1, and the same 5 amperes in line 2.

regards, Rod.

[Bill Reibelt]

I had to go the other way and set up a 110 volt system to my work area. I am in Australia 240 volt power. I had trouble getting 110 wall mounts and had the great luck to be in contact with Bert Kemp who sent me the required wall mounts to keep the cord plugs at 110 volt. I was advised to just mount 240 volt type wall mounts and change the cord ends to Australian type of three slots. I did not want anyone to plug a 240 volt plug into 110 volt (It would not work very well) or plug a 110 volt machine into a 240 volt wall mount (fry the machine and possibly cause a fire), Friends bought an electric blanket for their child and fitted it to a new bed and turned it on and the bed caught fire as the heater wires burnt the top of the bed. Found the electric blanket had been imported with incorrect wiring for this country. lucky the bed and a correct electric blanket was supplied and all of the other types were destroyed. Be very careful when dealing with different voltages. If you wish to get Australian wall mounts please feel free to contact me and I will send them to you at cost price.