3 wire vs. 4 wire for 220V

Can anyone enlighten me as to the difference between a 3 wire and a 4 wire hookup for 220V?
Is it possible to convert a 220V 3 wire setup to a 220V 4 wire setup?

Thanks!!!

 

When you say " 3-wire" 220v line, I would assume that you have 2 insulated copper wires and 1 bare copper wire. A "4-wire" 220v line would have 3 insulated copper conductors and 1 bare copper conductor. In a 3-wire 220v line, the two insulated wires each carry power to the appliance. These should be coloured black and red. This type of wire would be used to power for example an electric water heater. Because a 220v load does not need a neutral (white) wire to work, only 2 conductor wires are used with this application. A 4-wire 220v line is used for appliances such as stoves and clothes dryers. A 4-wire line has 2 insulated power wires (red and black), one neutral wire (white) and a bare ground wire. An appliance such as a clothes dryer actually has a mix of 220v and 110v circuits. Although the 220v circuit doesn't need a neutral wire to work, the 110v circuit does need the neutral (white) wire. This is why on some appliances a "3-wire" is all that's needed and for other appliances a "4-wire" is required. As far as converting this arrangement, a new "4-wire" should be installed from the panel replacing the "3-wire" arrangment. Consulting a licensed electrician for this highly recommended.

 

Sheetmet

Looking good, couldn't have said it better.

Wg

 

Wow, thanks sheetmet. That's the best explanation of this I've ever heard.

 

Thanks for the vote of confidence guys. I'm not a licensed electrician but have been around controls and wiring enough to at least fake it. My expertise is gas heating and ventilation. Just finished wiring a friends house addition, and it actually passed inspection. Cheers.