Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Electrical - AC & DC
Reload this Page >

Question about wiring for new receptacle from existing junction box

Question about wiring for new receptacle from existing junction box

Reply

  #1  
Old 12-30-13, 08:33 PM
Member
Thread Starter
Join Date: Dec 2013
Location: Canada
Posts: 11
Received 0 Votes on 0 Posts
Question about wiring for new receptacle from existing junction box

Hello everyone, long time reader, first time poster, thanks to everyone who helps out on this great site.

I am attempting to wire a new receptacle from an existing junction box in the dropdown ceiling of my basement. The new receptacle will be in the ceiling as well, as it is for the projector of my home theater.

The existing junction box holds a ceiling mounted light. When I took off the light to have a look inside the junction box, there were 4 wires, and I'm a little overwhelmed.

Knowledge:
- have read 2 great books about residential electrical work and safety. Have bought the necessary equipment to practice safe wiring, and try to do everything above code based on what I've learned.

Experience:
- installing/replacing basic switches, turning a single pole switch into a 3-way, etc.

This one is a new challenge for me, and I'm hoping to learn something from it.

Looking at the junction box from above, it looks like this:



Question #1: What is that on top of the junction box with the red wire? My thought was that it might be something for a ceiling fan, but this junction box only has a regular ceiling light.

The Junction Box

The wiring of the junction box is as follows:



Question #2: Is it possible to re-wire this junction box to support a new receptacle? If so, how would this best be accomplished?

Thanks for any insight or advice that anyone can provide. If anyone can help me understand what is going on with the wiring of this junction box, that would be appreciated.
 
Sponsored Links
  #2  
Old 12-30-13, 09:59 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 53,210
Received 378 Votes on 355 Posts
Welcome to the forums.

That is a transformer mounted to the top of that box. It's most likely the transformer that runs the doorbell.

Those two pigtails in your diagram are your "always live" connection points. You don't need to change anything.... however, that box is already undersized for the amount of wiring in it and it will get worse when you add another cable to it.
 
  #3  
Old 12-30-13, 10:17 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Received 1 Vote on 1 Post
I see three cables feeding into the box.

Those three cables appear to have a total of six insulated conductors, or wires, in them. The two leads for the transformer make a total of four insulated conductors. That many conductors plus the fixture requires more space in the box. The box needs to be replaced with a deeper one that doesn't have an open knockout in it.

According to your diagram, there are no pigtails in this box. There is one splice of the neutral conductors, one of the hot conductors and, presumably, one where the switch leg connects to the light.

If you need to add another cable to this location, a 1900 (4"square) box with a round device ring might serve you better.

How is this box supported?
 
  #4  
Old 01-02-14, 07:31 PM
Member
Thread Starter
Join Date: Dec 2013
Location: Canada
Posts: 11
Received 0 Votes on 0 Posts
I see three cables feeding into the box.
Whoops, good point, version 2 of the diagram has been updated to reflect the proper terminology, thanks!

According to your diagram, there are no pigtails in this box.
Some bad diagramming on my part. Both pigtails are actually in the box. I've updated this in version 2 of the diagram as well.

PJmax

Welcome to the forums.

That is a transformer mounted to the top of that box. It's most likely the transformer that runs the doorbell.

Those two pigtails in your diagram are your "always live" connection points. You don't need to change anything.... however, that box is already undersized for the amount of wiring in it and it will get worse when you add another cable to it.
Thank you. You're right, it is for the doorbell, thanks!

Based on these 2 responses, here is my plan of action...

1. Get a much bigger junction box that can safely support 5 cables and 2 pigtails.

idea:
- (4"square) box with a round device ring might serve you better.
2. Run a 14-2 wire to the proposed receptacle, and attach one conductor from this cable to pigtail #1, and the other conductor to pigtail #2

The end result would look like this:



Am I on the right track?

Thanks!
 
  #5  
Old 01-03-14, 02:19 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,946
Received 31 Votes on 27 Posts
I would run a xx-2 cable from the junction to the switch and then from the switch to the fixture. .

As far as the cable size the #14 would only be correct if the breaker or fuse is 15 amp.
 
  #6  
Old 01-03-14, 04:34 PM
Member
Thread Starter
Join Date: Dec 2013
Location: Canada
Posts: 11
Received 0 Votes on 0 Posts
I would run a xx-2 cable from the junction to the switch and then from the switch to the fixture. .

As far as the cable size the #14 would only be correct if the breaker or fuse is 15 amp.
Thanks! The breaker is indeed 15 amp.

There is already a 14-2 cable from the junction to the switch, but running another cable from the switch to the fixture would be fairly tough (but not impossible), as I don't have access to the wall behind the switch.

Any disadvantages or dangers to just running another cable from the junction box to the proposed receptacle? I'd be sure to use proper size connectors that can support 5 conductors in each pigtail.
 
  #7  
Old 01-05-14, 05:58 PM
Member
Join Date: Sep 2009
Location: Louisville KY
Posts: 578
Received 0 Votes on 0 Posts
I think PCboss meant to say receptacle instead of switch in his post. He just wanted to make sure that you didn't use 14gauge where on a 20 amp circuit. In answer to your question, you actually should connect the wiring to your new receptacle inside of the existing box after you upsize it to a larger box because of the number of wires in it.
 
  #8  
Old 01-05-14, 06:40 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Received 1 Vote on 1 Post
Originally Posted by Nashkat1
According to your diagram, there are no pigtails in this box.
Some bad diagramming on my part. Both pigtails are actually in the box. I've updated this in version 2 of the diagram as well.
I regret that I wasn't clearer in my earlier post, but no, it isn't bad diagramming. Your diagrams are a model of clarity. It's incorrect terminology.

Originally Posted by Nashkat1
There is one splice of the neutral conductors, one of the hot conductors and, presumably, one where the switch leg connects to the light.
You've diagrammed two multiwire splices but you've labeled them as pigtails. A pigtail is a piece of wire about 6" to 8" long that is used to connect a mounted device to a multiwire splice.

Run a 14-2 wire to the proposed receptacle, and attach one conductor from this cable to splice #1, and the other conductor to splice #2
That will work, since you say that this is a 15A circuit and replacing the switch-loop cable would be difficult.

Get a much bigger junction box that can safely support 5 cables and 2 pigtails.
Cables don't count, there are no pigtails, and splices don't count. What counts is the number of conductors, and the size and function of those conductors.

With 14AWG wiring, a rough guess is that you'll need a box with 22 in.[SUP]3[/SUP] of space in it. A standard 1900 box has no more than 24 in.[SUP]3[/SUP] in it. The device ring will add a bit more, and that space can be included if the added volume is marked on the ring.

To be on the safe side with this many conductors I would use either a deep 1900 box or an 11-b (4-11/16 inches square) box.
 

Last edited by Nashkat1; 01-05-14 at 07:22 PM.
  #9  
Old 02-18-14, 03:04 PM
Member
Thread Starter
Join Date: Dec 2013
Location: Canada
Posts: 11
Received 0 Votes on 0 Posts
I know it's been a while since I first posted this, but I just wanted to say thanks to everyone in this thread who helped me out! Nashkat1, pcboss, Msradell, and PJMax, I appreciate your help.

Because of your help, I was able to correctly install my receptacle into the ceiling for my projector, and it looks great!
 
  #10  
Old 02-18-14, 03:07 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
Thank you for letting us know how it worked out.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: