Stupid AC wiring question (220-ish Volts...)

Chuck Guzis cclist at
Thu Feb 5 22:17:40 CST 2015

On 02/05/2015 08:00 PM, Brent Hilpert wrote:

> In theory, if you have two 20A 120V circuits installed, you could also have 220V 20A from the same circuit(s) at the additional expense of just a 220V socket.
> However, local codes may have something to say about such an arrangement.

Have a peek in the breaker box--you should see the third neutral wire 
connected to the common neutral bus, which should also be connected to 
the ground bus.  At least that's the way it is in my house.

The practice for 240V appliance wiring in the US for many years has been 
3-wire, with the third wire used as both a neutral return for 120V 
circuits (many cooktops and ovens use this) and also the chassis ground.

Modern code demands that 4 wires be used in that case, with a separate 
ground run, but I suspect that the majority of installations for 240V 
appliances in the US still use the old 3-wire system.


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