240 in to the cabinet - how to wire 120?

[DrStein99]

I am retrofitting a Bridgeport Rigid ram, and have 240 VAC into the cabinet. Most of the appliances use 240 VAC but there are a few on 120 VAC.

Can anyone tell me - whats a good safe way to get 120 VAC from a 240 input?

A friend told me I can just take 1 wire from the 240 and use the earth-ground on the other end, and it would supply 120 vac. The Gecko stepper drivers run on DC, and the ground / shell for that power supply is connected to earth ground. I want to be safe, and - not afraid to spend money - but want to make sure its the right device for what I'm doing here.

-Erich Stein

[MrWild]

You actually should have four wires for your 220v line. This is, two power legs, one neutral wire, and one ground wire. If all you have are three wires running to your cabinet, you need to run a ground also. A good ground would be an actual grounding rod near your machine. Your machine then becomes safely grounded and the neutral wire is used for 110/120 with one leg of the 220/240.

[Al_The_Man]

Do not use the Ground as a neutral.
If the 240vac is from the typical domestic US supply, then you could run a neutral from the panel sourcing the 240v.
If you use a 240/120v isolation transformer, then if you decide to ground one side to set up a local neutral, then you are achieving the same thing as the former method, so there would be no point, but it would save you running a neutral.
Whatever method used, set up a common ground point and take all the system and service grounds and P.S. grounded commons to this point in the enclosure, never intentionally use the ground as a conductor.
Al.

[DrStein99]

I forgot to mention, I am using 240 VAC SINGLE PHASE. 3 wires, 2 hot and an earth ground.

Sounds like I need to buy an isolation transformer. The electrical cabinet is over 150' from the machine, running another wire is alot more involved then installing a device in 10 minutes.

Thanks for advise!

[Al_The_Man]

There was a recent post on the same subject, which I mentioned that if you go the customary way of grounding one side of the secondary right at the transformer, you will only need to fuse the secondary 'Hot' conductor, if not grounding the secondary, then you should provide a fuse in both legs.
BTW, the point that the secondary would be grounded is where you run your local neutral from.
Al.