# when to use 14/3 vs 14/2



## mopowers

Besides wiring a three way light switch, when is 14/3 wire typically used? Any examples?


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## <*(((><

15a 220v circuit

Sometimes people will use a 3 conductor wire when bringing power to an appliance before a switch.

People USED to run 14/3 or 12/3 in shops so that every other outlet was powered by a separate hot conductor and they all shared the same neutral, I'm not sure what code nowadays says about that, maybe someone else will enlighten us.


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## kbsparky

Multi-wire circuits, smoke alarms (interconnection), separate switches for things like a paddle fan, or bath fan/light, or ½-switched receptacles, etc.

We even use 14-4 to carry both a hot and neutral along with 3-way travelers from one switch to another, to maintain the lighting circuit at the far end of the room.


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## darren

KBsparky do they make 14/4 loomex or have you used armoured cable when you did this.


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## jlhaslip

Kitchen - use 14-3 to run 2 circuits to split tab receptacles.


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## DangerMouse

<*(((>< said:


> 15a 220v circuit


with 14-3? 15a?
i'm confused.......

DM


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## kbsparky

darren said:


> KBsparky do they make 14/4 loomex or have you used armoured cable when you did this.


We get real 14/4 cable. It has a black, white, red, and blue conductors in it, as well as the bare ground.

There is also what is called 14-2-2 cable available, which has the black, white, red, and red/white striped conductors.


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## Speedy Petey

DangerMouse said:


> with 14-3? 15a?
> i'm confused.......


Me too. 
Why would you need 3-wire for for a *240v* circuit??


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## teamo

yes they make 14/4 but it is usually only carried by the supply houses not the big box stores.


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## AllanJ

Speedy Petey said:


> Me too.
> Why would you need 3-wire for for a *240v* circuit??


For a combination 120/240 volt circuit, also referred to as a multiwire branch circuit when all of the loads are 120 volt (red-white or black-white).

Also for the same switched situations as may be encountered in 120 volt circuits.

For a simple 240 volt only circuit, 2 wire cable is sufficient.


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## Speedy Petey

AllanJ said:


> For a combination 120/240 volt circuit, also referred to as a multiwire branch circuit when all of the loads are 120 volt (red-white or black-white).
> 
> Also for the same switched situations as may be encountered in 120 volt circuits.


Then it is not a "240v" circuit any more.


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## Stevies3

My builder ran 12-3 - 30A for hot water tank (4500 watt each element) there none simultaneous 

2 hot's ( 120v ea) plus a neutral & ground. This is often done with electric ranges too


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## rjniles

Stevies3 said:


> My builder ran 12-3 - 30A for hot water tank (4500 watt each element) there none simultaneous
> 
> 2 hot's ( 120v ea) plus a neutral & ground. This is often done with electric ranges too


Your builder done you wrong. Wire should be 10ga for a 30 amp circuit. Also 3 wire cable is not requires as a water heater does not need a neutral. 10-2 is what is called for.


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## Speedy Petey

rjniles said:


> Your builder done you wrong. Wire should be 10ga for a 30 amp circuit. Also 3 wire cable is not requires as a water heater does not need a neutral. 10-2 is what is called for.


Absolutely correct on all points. 
#12 is NOT acceptable for a 4500 watt water heater.

Probably one of those "all-in-one" builders.


> "Sure, we do it all. Plumbing. Electric. Drywall. Painting. We don't need no stinkin' subs!"


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## vseven

The original electricial used 12/3 in multiple places from the breaker box to where two circuits would then begin, I'm assuming to save wire. For example 12/3 was landed on circuit 17 for smoke alarms and 19 for basement lighting. Then 30' from the breaker box the circuits split and went on their separate ways. Unfortunately for me I was going to change out circuit 19 for a AFCI and add more lights but I couldn't do that without rewiring from the box so I left the existing breaker.

I also used 12/3 to add another smoke alarm to the existing and used the red wire as the common signal.


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