3 way switch question and adding light/switch


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Old 02-19-15, 01:21 PM
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3 way switch question and adding light/switch

Hello all.
I have a 3 way switch at the bottom of my stairs which goes to the light in the hallway and then off the light is the other 3 ways switch. (Picture below) Im not really familiar with it being wired this way, usually I see "switch, switch, light". I would like to add another light and if at all possible another switch at the other end of the hallway.
1..To add the light I assume I would just get power off the Neutral and Hot going directly into the Light. Is this correct? (picture below)

2. Is it possible to add another switch with the way this was setup? I believe that if it were set up "switch, switch, light", I would have to get a 4 way switch in between the two 3 way switches. Is this correct? But with this setup I have no idea.
Any help would be appreciated. Thanks
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Old 02-19-15, 02:32 PM
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To add the light I assume I would just get power off the Neutral and Hot going directly into the Light. Is this correct
Yes.

A 4-conductor cable run from the ceiling to the new 4-way would work. Getting the 4-conductor cable in a short length might be the problem. Not sure BigBox sells it and a supply house probably wouldn't cut to length so two two conductor cables (but that may not meet code) or Smurf with individual conductors may be a better way.

Note: I have not figured box fill but my gut felling is you are going to need a deeper box.

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Last edited by ray2047; 02-19-15 at 03:22 PM.
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Old 02-19-15, 05:02 PM
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A deeper box for the light fixture? or switch? Never using smurf tubing, If I were to go that route, what exactly do you mean individual conductors? Also as far as 14-4 wire. The only thing I really see is this ..
Southwire 14-4 SJOOW 300 Volt Black (By-the-Foot)-55812399 - The Home Depot.
Not really sure if that is what is needed. Im rather new to this and wasn't sure what the sjoow etc meant. Or if this wire was overkill. thanks again. I appreciate your knowledge
 
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Old 02-19-15, 05:07 PM
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The "box fill" when wiring up the additional switch and light as shown above ...

You will need 28 cubic inches (32 ci for 12 gauge wire). You might need to add an extension ring on the ceiling box and then replace the light fixture or light fixture canopy.

(Existing 3 wire cables, 3 points each. New 4 wire cable for 3'rd switch, 4 points. New 2 wire cable for 2'nd light, 2 points. All the ground wires, 1 point. all the cable clamps, 1 point. Pigtails i.e. short lengths wholly within the box, 0 points each. Taps, i.e. the 18 or so gauge wires pre-connected to the light fixture, 0 points each. Wire nuts, 0 points each. Total points, 14. Two ci for each point using 14 gauge wire, 2-1/4 ci per point for 12 gauge.)

Another way would be to string a 3 wire cable from one of the existing switches to the third switch location. The 4 way switch goes in the affected existing switch box. The 3 way switch taken from the affected location goes in the new switch box.

If the best route for the new cable from the existing switch box goes past the existing light fixture, have the new cable pass around the outside of that box.

Any wire attached to a switch terminal is considered hot. Ergo a white wire attached to a switch terminal is not neutral or common. However the latest (National Electric ...) code requires that both ends of such a white wire have a band of tape or stain a color other than green. The wire (switched hot) attached to the hot terminal or black wire of the light fixture may not be the white wire of the feed cable. For individual conductors e.g. THHN wires in conduit, white wires may not be used for hot purposes and colored wires #6 and smaller may not be used as neutrals, e.g. that's all you have on hand.
 

Last edited by AllanJ; 02-19-15 at 05:34 PM.
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Old 02-19-15, 06:28 PM
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Southwire 14-4 SJOOW 300 Volt Black (By-the-Foot)-55812399 - The Home Depot.
Not wire it is cord but you need cable, 14-4 NM-b.

Smurf is slang for ENT, non metallic conduit.

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Individual conductor are single wires not in a cable or cord.
 
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Old 02-19-15, 08:08 PM
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Sometimes you have to think outside the (junction) box.

Replace existing three way switch with four way switch and use 3wire cable to extend circuit to newly relocated three way switch.

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Old 02-19-15, 08:29 PM
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Dang PJ, that is brilliant. Knb, ignore my post.
 
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Old 02-20-15, 05:58 PM
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Copy Ray, Ignoring your post ..Haha. jk. Thanks a lot though for the input on everything and thanks for working with my picture provided. Makes it a lot easier to understand.. A few more questions.

1. Doing it PJs way wouldn't call for me getting a bigger box?

2. If I were to want these on a dimmer switch. Would that require anything else? and Could i use a dimmer switch on just one switch. How would I go about doing that.. Thanks again
 
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Old 02-20-15, 07:20 PM
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A dimmer has three conditions or states: off, full on, and dim. A traditional 3 way or 4 way setup will toggle back and forth between any two of those states with the third state unachievable at some of the switch locations.

The best way to handle this is to install a 3 way dimmer kit rather than traditional 3 way and 4 way switches. For the three switch locations you will need to find a kit with one dimmer unit and two remote units. This allows you full control of the light from any of the switch locations.

The wiring to the switches would be redone with black as the raw (always on) hot, white as neutral, and red as a control line interconnecting the dimmer and remote units.

They also make dimmer kits with battery operated wireless remote units. If you bought one of these kits, you would tape or cap the ends of the wires already in the remote boxes, label the ends, and curl them up and push them to the back of the box and then install the remote unit. The main dimmer unit goes in the box with the cable/wires continuing to the light fixture.
 

Last edited by AllanJ; 02-20-15 at 07:36 PM.
 

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