Installing Wall Switch

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  #1  
Old 12-31-10, 03:13 PM
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Installing Wall Switch

Okay, time for a new project. I am taking down a ceiling fan / light combination to install a small, simple light fixture only.

There is no wall switch to operate the fan or lights now.

Installing an old work box in the wall for a light switch seems really easy (?), but I'm unsure of how to run the wire down the wall. Can I just run Romex down, attach the black to the top of the switch, and then use the neutral wire (marking it somehow) to run the bottom of the switch back to the hot wire in the attic? Thanks...
 
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Old 12-31-10, 03:27 PM
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Can I just run Romex down, attach the black to the top of the switch, and then use the neutral wire (marking it somehow) to run the bottom of the switch back to the hot wire in the attic?
Yes, but standard practice the Romex would run through the attic to the ceiling box* not the attic.

*Yes, you could install a J box in the attic but that just makes it more complicated and could puzzle the next person who works on it.

You might want to use 12 or 14**-3 instead of 12 or 14**-2. You would then just use the black and red for now and if you ever installed a ceiling fan with no remte you could add an extra switch.

** Match wire size to breaker size.
 
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Old 12-31-10, 04:09 PM
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If you decide to only run a two wire + ground cable to the switch you will install what is called a switch loop. The white will be re-identified with magic marker or tape in a color other than green. This will provide the power to the switch. The black will be the switched hot back to the fixture.
 
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Old 12-31-10, 07:39 PM
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So, installing the "switch loop" is basically done with just a piece of Romex...

I have never uninstalled a ceiling fan before so I don't know what to expect in the attic. This is how I envision the wires running: Breaker box --> Fan (I install J box here...) --> Added Romex leaves J Box --> Switch --> Back to J Box.

Do I not have to install a J-box over the light fixture?...or will the fan have a box I could just use? Thanks...
 
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Old 12-31-10, 08:54 PM
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The fan should have already had a junction box installed above it that it was mounted to. You can use this as a junction point for the switch loop.
 
  #6  
Old 01-01-11, 10:13 AM
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2011 nec requires a neutral wire for a switch loop, so you will need to use 12/3 for the loop if it was adopted yet.
 
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Old 01-01-11, 10:57 AM
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Which means it also has a ground wire in the sheath? I'm not good with the terminology.
 
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Old 01-01-11, 11:05 AM
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Originally Posted by JFS321 View Post
Which means it also has a ground wire in the sheath? I'm not good with the terminology.
When speaking of branch circuit wiring the ground wire in cable isn't counted. 12-3 would have 3 insulated wires and an uninsulated fourth wire, the ground.

Now fixture cable is different. If speaking of service cords such as SOW used for extension cords and appliance cords the ground wire is counted. So 12-3 SOW would have only three wires.
 
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Old 01-01-11, 11:07 AM
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Non-metallic cable, commonly called Romex, but more properly NM-B cable has a grounding conductor contained within the sheath.

JS was stating a new code requirement that a neutral conductor now be run in a switch loop. This is new to the 2008 NEC. This would be a white conductor spliced to the neutrals in the fan box. You would then use the black and red as the feed and return from the switch to the fixture. The white would be unused until a switch that required a neutral was installed.
 
  #10  
Old 01-01-11, 02:38 PM
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Thanks, guys. I just walked in the door from Lowe's and I bought 25 feet of 12/2 Romex. I see now I should have gotten 12/3 but I'm going to still use it...technically I'm only a day late I suppose with the new codes.

Anyway, I have the old work box and drywall saw ready to go...and I've measured in the attic where I need to feed down the cable. I'll let you know how it goes.

I didn't get a junction box yet (the fan didn't have one either and I forgot to get one at the store). Is a regular plastic box with a cover okay? No need to get metal I guess?
 
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Old 01-01-11, 04:19 PM
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I didn't get a junction box yet (the fan didn't have one either and I forgot to get one at the store).
Then what was there?How was the fan fastened?

Is a regular plastic box with a cover okay?
The light is the cover. The box is mounted flush with the ceiling open side down. I'd suggest a plastic new-work box since you have access from the attic. The box will come fastened to an adjustable bar that you fasten to the joists on either side. If the fan hole is against the joist you can get a box that nails to the joist. Get a 4" box.

The 12-2 is fine. If this is a 15a circuit you could have used 14-2, a bit easier to work with.

Note: The bar will have to be reversed so the mounting ears point up since you are fastening from the attic.
 

Last edited by ray2047; 01-01-11 at 04:35 PM.
  #12  
Old 01-01-11, 04:56 PM
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The fan was attached to the ceiling with a mounting bracket, and the wires were passed through the center of the bracket through a small hole in the ceiling/attic (no box). <Side note: I have been told that the two men who built homes in this subdivision were a father/son electrical team with another relative doing the inspecting, and several home fires over the last couple of decades were attributed to their shoddy work. No box over a fan may not be a big deal...I obviously don't know.>

The picture was a big help. I suppose I should just get a bigger box than I think I need to be sure all the splicing fits.

I was afraid that I could have gotten 14/2 instead of 12/2 but I wasn't sure while I was in Lowe's. Another side note: I have a single switch beside the kitchen door working an outdoor light just underneath the attic entrance. I installed an outlet in between the switch and light up in the attic so I could bring up an external light source. Anyway, the wire used for that circuit was 10/2. I'm an amateur but I sure didn't think that made sense and it was hard as heck to work with.
 
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Old 01-01-11, 07:02 PM
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The picture was a big help. I suppose I should just get a bigger box than I think I need to be sure all the splicing fits.
No, that would cause problems with the mounting bracket if it was more then 4". You can increase the volume by using a deeper box but that is definitely not needed with only two cables.

I was afraid that I could have gotten 14/2 instead of 12/2 but I wasn't sure while I was in Lowe's.
If the breaker is 15a you use #14 minimum. If the breaker is 20a you use #12 minimum. The breaker size is usually on the end of the handle.

Anyway, the wire used for that circuit was 10/2.
It is not a code violation to use over size wire and in some cases you need to however as you noted it is harder to handle. I'd suggest you get a book such as Wiring Simplified Available at Amazon, Home Depot and other places or a similar beginners guide.
 
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Old 01-02-11, 07:03 AM
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Thanks, guys. I just walked in the door from Lowe's and I bought 25 feet of 12/2 Romex. I see now I should have gotten 12/3 but I'm going to still use it...technically I'm only a day late I suppose with the new codes.
Codes must be adopted by ordinance. Your area likely is still on the 2008 NEC or possibly even an earlier version. My area finally adopted the 2008 NEC, with a list of amendments, just 60 days ago.
 
  #15  
Old 01-02-11, 02:48 PM
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The wire is in the wall...after a LOT of work. I didn't realize that there were horizontal studs about 2' down the wall from the ceiling. So after much drilling, cursing, and wondering, I finally cut a huge piece of the drywall out and drilled through the studs as needed to get the wire down to the box.

The J box in the ceiling was fairly easy to install. But how do you normally cut a 4" in hole in the ceiling? I used a drywall saw and it was ugly and messy.
 
  #16  
Old 01-02-11, 03:04 PM
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I use a drywall saw too. The base of the light should cover minor sins. Don't know what to say but you trace a line using the box as a template then cut. I have seen very hard and very soft dry wall that was more difficult to cut.

Oh yes they aren't common any more but fire stops can sure ruin you day. You can use a flex bit but they are expensive, If they were only two foot down instead of the usual four foot I would probably have cobbled together two one foot bit extensions. But hang in there. A lot is learned after you say your first four letter word.
 
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Old 01-02-11, 03:12 PM
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Originally Posted by CasualJoe View Post
Thanks, guys. I just walked in the door from Lowe's and I bought 25 feet of 12/2 Romex. I see now I should have gotten 12/3 but I'm going to still use it...technically I'm only a day late I suppose with the new codes.
Codes must be adopted by ordinance. Your area likely is still on the 2008 NEC or possibly even an earlier version. My area finally adopted the 2008 NEC, with a list of amendments, just 60 days ago.
Just to be clear I wasn't really concerned with 2011 codes when I suggested using 3-conductor cable, Only that you might later want a ceiling fan and light controlled by separate switches.
 
  #18  
Old 01-02-11, 05:09 PM
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Part of my problem sawing I think was that the ceilings are double-thick...the house has ceil-heat throughout. I hate cutting into those wires but the J box only required cutting two.

I'm starting another post because I haven't had any luck in changing out the old thermostats as of yet.
 
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Old 01-02-11, 05:14 PM
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the house has ceil-heat throughout. I hate cutting into those wires but the J box only required cutting two.
Wait! is this abandoned? If not you can't just cut the wires.
 
  #20  
Old 01-02-11, 06:35 PM
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Oh, no...I'm going to splice in the switch tomorrow and consider a closed case, I hope!

Er...I can't just ignore the two little white wires cut in the ceiling? I cut them flush with the drywall. I had heard that they were impossible to repair...
 
  #21  
Old 01-02-11, 06:40 PM
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If I wasn't clear I mean that I am going to install the new light/switch tomorrow...and I had planned to ignore the two white ceil-heat wires that were cut when installing the J box.
 
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Old 01-02-11, 07:11 PM
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Originally Posted by JFS321 View Post
Part of my problem sawing I think was that the ceilings are double-thick...the house has ceil-heat throughout. I hate cutting into those wires but the J box only required cutting two.

I'm starting another post because I haven't had any luck in changing out the old thermostats as of yet.
I'll bet you have two layers of drywall with radiant ceiling heat sandwiched between them. If the heat in that room was still working, you may want to try it again because I doubt it is 100% operational since you cut the wire. And yes, they can be repaired, but maybe not now since you cut them flush. I hope your house has had another heat source installed since it was built.
 
  #23  
Old 01-03-11, 03:35 PM
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New light, switch, and huge holes in the wall. I consider this total success, even if drywall screws are now on my shopping list.

Thanks for the help.

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Last edited by JFS321; 01-03-11 at 03:36 PM. Reason: Take two...
  #24  
Old 01-03-11, 04:15 PM
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Nice job.

..............
 
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