How do I convert a 220v ac disconnect to 120v?

Question

I have an old ac disconnect for a wall ac unit. It is 220-240v with a Black, White and Green wire. The white and black both carry 110v. I know that modern wiring has a red wire and then black white (neutral) and green for ground. How the heck do i change this to 120v?

Answer 1

In addition to Liz's answer if the disconnect is a fused disconnect you need to bypass the fuse in the neutral line. If it is not fused then it is legal to simultaneous disconnect the hot and neutral.

Answer 2

You will have to look at the other end of the cable in the circuit breaker box and see how those wires connect into the panel. You will disconnect one of the wires (white) from one of the hot terminal blocks and connect it to the neutral terminal in the box (like the other white wires). Connect the green wire as a ground. That will make it a 110 volt circuit. Then you change the disconnect according so that there is only 1 hot wire that is in the switch (black) and the neutral wire (white) is not connected into the switch. The ground is used for grounding.

Answer 3

Very simple! Back in the main circuit breaker panel that feeds your local disconnect, turn off the 2-pole feed circuit breaker that is supplying the 220 volts to your 220 volt ac circuit. Then remove the white wire from the 2-pole breaker and relocate it to the white common buss in the circuit breaker panel. If you wish, you can still use the 2-pole breaker as a single pole breaker to continue to supply the circuit!

PLEASE BE CAREFUL while working in the circuit breaker panel. If you are not an electrician, I suggest that perhaps you should turn off the main disconnect in the panel to remove all of the power in there while you are relocating the white wire!



PS...It would help any future electricians working in the panel if you would mark that white wire as to where it comes from in case someone would want to reconnect it to the 2-pole breaker to restore the 220 volt capability. (Marking it "to 220 V AirCond" OR "AC breaker" would be enough)! Use a piece of white tape or whatever



Once the white wire has been relocated, the circuit will be 120 volts when you turn the 2-pole breaker back on.