Wiring with 14/3 when only 14/2 is needed

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Old 02-26-11, 07:22 AM
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Wiring with 14/3 when only 14/2 is needed

I'm finishing my basement and about to start the electrical. I have about 100ft of 14/3 that I would like to use instead of having to go out and buy 14/2.

Would code allow me to use the 14/3 instead of 14/2 and pass with the inspector? Could I just use a wirenut to cap off the 3rd (red) wire even though it would not be connected anywhere in the series?

All my switches are single pole and receptacles run in parallel.

thanks
Mark
 
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Old 02-26-11, 07:30 AM
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The biggest issue is to make sure your boxes are sized for the 2 extra conducotrs that will be in each box. You are adding an additional 4 cubic inches of allowance needed. For example a box with 2 14-2 cables and a receptacle would calculate out as 7 conductors at 2 CI each for a total minimum capacity of 14 CI. Using the 14-3 the conductor count goes up to 9.

To figure box fill each ground counts only once, a device counts as two, each conductor counts once.

To clarify two cables with a ground in each would still be one.
 
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Old 02-26-11, 08:17 AM
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ok, yes, I need to count for the extra wire in box volume. But it sounds like it can be done with an unused wire capped off.

thanks
 
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Old 02-26-11, 08:51 AM
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You could even use a 2-pole breaker, with the top and bottom on different sides of the breaker.
 
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Old 02-26-11, 12:36 PM
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Justin, what are you suggesting? Making a 240 volt circuit of this? I don't think that is what the OP had in mind. He just wants to abandon the red wire in the 14-3.
I would mention, too, while doing your switch loops, go ahead and use the 14-3, but use the red and black for the switch loop, connect the white to the neutral in your fixture, and cap it off in the switch. It is coming code, and you may be glad you did.
 
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Old 02-26-11, 02:10 PM
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Thanks Chandler, yes I'm looking to abandon the red wire, want to make sure that I'm still within code.

What would be the purpose using the red and black for the switch loop, connecting the white in the fixture but capping it (white) off at the switch? Kind of new to wiring so I'm trying to follow/learn.

thanks
 
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Old 02-26-11, 02:41 PM
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Originally Posted by wirezcrossed View Post
Thanks Chandler, yes I'm looking to abandon the red wire, want to make sure that I'm still within code.

What would be the purpose using the red and black for the switch loop, connecting the white in the fixture but capping it (white) off at the switch? Kind of new to wiring so I'm trying to follow/learn.

thanks
Basically a white is not really a white in a switch loop because white is reserved for neutrals. It is supposed to be recolored red, black or any other color except green gray or remain gray. If you have a red and black then you use red and black. By convention not code black is power in and red is power out to fixture.

See also: http://forum.doityourself.com/electr...itch-loop.html
 
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Old 02-26-11, 03:32 PM
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Using the red and black will keep you from having to tape the ends of the white wire, and will give you a neutral in the switch box for the later installation of a dimmer switch or other device that will require a neutral, where, otherwise, with only the black and remarked white, you would have no neutral. The link Ray gave will describe it in full.
 
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Old 02-26-11, 05:41 PM
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Exclamation

Justin, what are you suggesting? Making a 240 volt circuit of this? I don't think that is what the OP had in mind. He just wants to abandon the red wire in the 14-3
I'm suggesting using a mwbc. I LOVE those things.
 
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Old 02-26-11, 06:08 PM
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But on a single run, what would be the advantage?
 
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Old 02-27-11, 05:27 AM
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You get half of the receptacle on one pole, the other half on the other pole. It's like having a 30A circut, but this is safe.
 
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Old 02-27-11, 05:36 AM
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It would work, but I'd hate the safety consequences for a homeowner. Think about it. They have a lamp on and want to change out a broken receptacle. They turn off the breaker to the lamp and dig in. Unless you know there is a MWBC there or are trained to check things out like we are, there could be a hidden danger. I like keeping it simple.
 
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Old 02-27-11, 10:59 AM
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yes, I like things simple.

Thanks for all the help. I might be back for more.
 
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Old 02-27-11, 04:48 PM
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It would work, but I'd hate the safety consequences for a homeowner. Think about it. They have a lamp on and want to change out a broken receptacle. They turn off the breaker to the lamp and dig in. Unless you know there is a MWBC there or are trained to check things out like we are, there could be a hidden danger. I like keeping it simple.
That is why code requires a 2P breaker.
 
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