2-wire v. 3-wire wiring

[Kinger]

Maybe I am missing something...........I don't wuite understand when to use 2-wire or 3-wire (assuming both have a ground)?

I know that 3-wire is used on 3-way switches.

Is there a need for 3-wire if all the outlets on a circuit are GFI protected?

Thanks

[dipper]

There's general books on wiring available at home improvement stores; it sounds like they would be a good read for you.
Is there a need for 3-wire if all the outlets on a circuit are GFI protected?
No.

Only time you'd use three wire for an outlet would be if you wanted one side switched, or if the outlet is gonna be on a different breaker (in which case the other breaker needs to be below the first breaker with a handle tie between them).

[brad d]

Big heaters/boilers also need 3 wire..

[LoneGunman]

240v circuits that require a neutral also use 3 wire. Cords screw a lot of people up, 12/2 romex is a black, white and a ground but #12 two conductor SO cord is only a black and white, 3 conductor would be a black,white and a ground.

[PAToyota]

240v circuits that require a neutral also use 3 wire.

That should be "240v circuits that require a neutral for a 120v circuit also use 3 wire.

No 240v circuit is going to require a neutral.

[Dave88LX]

3-wire if you're running a switch to a ceiling fan/light combo and want to independently control the lights and fan from the switch.

[LoneGunman]

That should be "240v circuits that require a neutral for a 120v circuit also use 3 wire.

No 240v circuit is going to require a neutral.

:rolleyes: Ummmm yeah, it's a 120v circuit within the equipment that operates on 240v, most people would realize that. Of course if you want to get technical and nitpicky, there is no such thing as a neutral. The proper term is "grounded conductor" and the proper term for a ground is the "equipment grounding conductor". On forums such as this it's a lot easier to use the commonly used term rather than the correct term as "grounded conductor" and "grounding conductor" sound very close.

So when someone asks "Is a neutral required for my 240 volt circuit in my kitchen" ,we should tell them "no" because as you stated, no 240v circuit requires a neutral?

[kbs2244]

What dipper said.
This is scary basic stuff.
Just remember, if you live in a Romex OK area,
that the bear wire is the ground and dosn't count as a "3 wire" circuit.

[Kinger]

Thanks for all the replies.

I have a couple of basic books that I need to get my head into.

I was typing out loud at lunch today. Thanks.:thumbup:

[PAToyota]

:rolleyes: Ummmm yeah, it's a 120v circuit within the equipment that operates on 240v, most people would realize that. [snip]

So when someone asks "Is a neutral required for my 240 volt circuit in my kitchen" ,we should tell them "no" because as you stated, no 240v circuit requires a neutral?

Based on a lot of the questions asked it seems that "most" people have a lot of confusion about 240V and don't understand 240V vs. 120V and why you need a neutral because here and elsewhere you get a lot of people asking what they connect the fourth wire to for a 240V compressor or welder or such and then start citing the stuff about code requiring four wire for 240V appliances instead of three like you used to be able to do.

Clarifying that the four wire setup is only used when you need the neutral for a 120V circuit helps people to understand the difference between why a dryer or range needs the neutral and a compressor or welder does not.