12 gauge -> 14 gauge

May 23, 2008 11 Replies

Hi,

I'm putting this question in a new thread b/c it seems to have gotten lost in an old thread.

I've installed a dedicated 20 amp circuit for a heater/fan/night light/ light combo. Naturally, I used 12 gauge wire to deliver the power to the unit. But I am faced with this problem. There are four sets of wires that need to run from the switch box to the unit which means a total of five sets of wires which the box just won't take.

Is it OK if the unit is connected to the switch with 14 gauge wire. Or if I use 12 gauge for the heater part and 14 guage for the rest?

Many thanks in advance!

Aaron

I've installed a dedicated 20 amp circuit for a heater/fan/night light/ light combo. Naturally, I used 12 gauge wire to deliver the power to the unit. But I am faced with this problem. There are four sets of wires that need to run from the switch box to the unit which means a total of five sets of wires which the box just won't take.


Is it OK if the unit is connected to the switch with 14 gauge wire. Or if I use 12 gauge for the heater part and 14 guage for the rest?


Many thanks in advance!


Aaron


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No, it's not OK, but you don't need four sets of wires, all you need is six wires including ground. I would get a length of 1/2" greenfield and run it from the switch box to the fixture

Thanks! (But what is "geenfield"?)

Thanks! (But what is "geenfield"?)

Flexible metal conduit that you pull your own conductors through. It looks similar to the armor on BX cable, but it comes in bigger diameters. I just ordered some 1 1/2" Greenfield today for a job I'm doing. You will need to pull four colored conductors (Other than white or green) plus one white and one green. Use stranded wire as it is easier to pull through flex.

If the switchbox is too small you should change it. You could use a 4" square x 2 1/8" box with a switch ring or a 4 11/16" square box that is 2

1/8" deep with a switch ring. There are more choices for boxes at an electrical supply house than at Home Depot.

Each #12 conductor requires 2.25 cubic inches in the switchbox. For each device such as a switch a deduction of two wires must be made. The grounding conductor only counts as one. At the very minimum with one device you will need space for 10 wires x 2.25 cu. inches = 22.5 cubic inches. If you plan to have more than one switch you need 4.5 cubic inches for each one.

Tables 314.16(A) & (B) should help.

Thanks! (But what is "geenfield"?)

Greenfield is bx cable without the wires .You pull your own wires in the same way as pipe .Also I would think about using 3/4"as the #12 wire will be tight.

Why would you use Greenfield in a residence?. Just use Smurf tube (type ENT). That is the blue plastic stuff at the home store.

As a seasoned professional, I find it beneath me to use any product with the word "smurf" in it's name

In all of my years in the trade I have only seen one electrician use that stuff. He was a very young guy and wired an entire house with that stuff. I thought that it would have been faster to use cable such as Romex. I remember seeing an ad for ENT a few years ago that had a picture of the stuff being installed within a soon to be poured reinforced concrete decking of some sort. The stuff was all over the place and I thought to myself that it must be difficult to pull wires into it since it was bent every which way.

Simple answer? No... If you have a 20amp breaker you cannot use ANY 14 gauge wiring in that circuit.

ENT has a bad reputation among pros because it doesn't really require much skill to install. If you listened to the IBEW we would be using RMC everywhere. I guess if they had made it Olive Drab color and called it Rambo guys would like it better. In real life Smurf is not a bad product and it is very easy to shove wire into it. (in fact Carlon tried to get the 360 degree limitation expanded to 720) You just need to be sure you don't have a sharp edge on the pointy end of the bundle that will hang on the corrigations. I just did a smurf job and I found by accident that the red tape the concrete guys use for sealing up the vapor barrier is the best thing to wrap the end of a wire bundle with. It sticks well, it is slick and it doesn't leave a gummy mess on your hands or the wires like the ubiquitous duct tape.. This was a situation where the raceways were buried in poured block cells and smurf seen to be the easiest way to go. It worked out great.

Thanks for all the responses.

I have one more question about combining the neutrals from the fixture. The fixture has 4 neutral wires, one for each of the functions. If it were OK to combine those, why wouldn't they just give you one neutral, why do have give you 4?

Thanks!

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