Where would you use 14-3 wire vs.14-2?

Question

I'm trying to learn about electrical but I'm not understanding cases where you would use 14-3 instead of 14-2? Does it depend on the device being wired? If someone can provide an example of where you would use 14-3 over 14-2 and why, that would be extremely helpful. Thanks!!

Answer 1

Probably the most common example would be for a 3-way switch, where you can turn one common light on and off from 2 different locations (upstairs/downstairs, for example).

Answer 2

14-3 would typically be used in a 3-way switch circuit.  Also might be used with two single pole switches in one box controlling different functions of a fixture -- a fan and a light, for example.

Three strand wire is also used for 240 volt applications, but there aren't many of those situations where the load is light enough to use 14 guage wire.

In any case, a ground wire is generally required.   The ground wire is not included in the strand count, but is noted after so you would have 14-2 w/G or 14-3 w/G.

Answer 3

Here are a couple of other uses for the 14/3 wg romex. If you have a switced receptacle on a split circuit that is fed from the switch box, and then all of the receptacles are switched, the 14/3 is needed. The jumper on the side of the receptacle must be removed to make it work. Another use is for a smoke detector system where one unit will trip the remaining system. The power is on the black and white, the red is the alarm function.

It is also used for any 3 phase load of 15 amps or less on 230 or 480 volt circuits. For some motor circuits this may be protected by a 30 amp breaker. Ampacity and voltage are different functions. More power is transmitted at higher voltages for the same current. This is a motor use condition, not normal load in a residence.  This is one of the few cases where the wire may be smaller than it required by codes.  

Answer 4

I am not an electrian but I would use 14/3. The third wire is the ground and is the "code" where I live. Frankly I think 14/2 would be dangerous.

Answer 5

Be_A_ ???  has the right answer. 14 guage wire is too light for most 230 Volt applications. Low level loads like fans and lights is all I'd ever use it for.