Asked in Home ElectricityNew Electrical WorkModification of Old Electrical Work
Can a 240 volt circuit ground wire be used as a neutral?
August 18, 2012 11:58AM
If your equipment is grounded using a separate ground wire, and the neutral wire breaks, the appliance may not function, but no one will be hurt.
If, on the other hand, you use the ground wire as the neutral, and it breaks, IF THE APPLIANCE HAS A METAL CHASSIS AND/OR CASING CONNECTED TO THE GROUND WIRE IT WILL BECOME LIVE! Anyone touching it could be killed!
It's just not worth saving a few dollars over. Buy and install the proper 4-conductor cable (called 3-wire with ground) and be safe.
A different take from a professional appliance installer and electrician:
Up until the mid to late 1980's the ground and neutral were tied to the same bar in the panel. So unless someone who has a house built prior to this has had a complete electrical service rebuild the ground and neutral of all of the circuits are connected to the same place.
If you have an older home and there are only three wires feeding a 220v appliance the ground and neutral are interchangable. In fact, if the unit had two hots, a neutral and a ground, the ground and neutral were tied together. This is still acceptable practice and is diagrammed in the specifications for every appliance appliance that I am aware of. (Only Miele for a time was particular about not mixing the ground and neutral, although they could never tell me why it mattered. They have since dropped that requirement).
There are a lot of new 220v appliances that have only three wires. Usually two hots and a ground. It would be perfectly fine to hook the ground to the neutral if that was all you had.
As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.