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Tappimg off existing outlet

sharcitect | Posted in Construction Techniques on January 14, 2009 09:07am

Hello all-
I’m a new member but a long time FH reader.
I was wondering if you could help me. I’m not sure I want to take on this work myself and will base the decision on how involved / difficult it is.

I have an existing outlet near the floor level and would like to mount a sconce on the wall 5 or 6 feet above it. I would use a sconce that has an integral switch so I wouldn’t have to install a separate wall switch. Could someone walk me through the process of tapping off the existing outlet for the light? I believe the wiring has to be BX here.

Thanks

Reply

Replies

  1. DanH | Jan 14, 2009 10:01pm | #1

    The worst thing is that you have to fish the wire down the wall and somehow get it attached to the box. Doable if there are no other wires coming into the box (and you're in the same stud bay, with no fire stops), but a little like building a ship in a bottle.

    (You might want to consider the issue of fire stops. If you're using BX this may be the Chicago area where they're still worried about cows and lanterns, and so there may be fire stops halfway down.)

    Basically, you first turn off the breaker, then open the box and examine the incoming wires. If only one cable is coming in that's great! If two are coming in you'll have to work harder. If three (or more) are coming in it's going to be just about impossible. Also, you need an unused "knockout" on the top of the box.

    Next you cut an opening at sconce height for an appropriate "old work" box. But you don't install the box yet. You pry out the "knockout" in the box below and then fish a length of cord (about like curtain draw cord) down the hole, long enough to pile up some on top of the box. (But don't let go of the top end!) Then with a coathanger hook, reach through the knockout, hook the cord, and pull it into the box.

    (There are other ways to do this fishing, but the above is what's worked out best for me.)

    That accomplished, you prepare your piece of BX (make it 6-8 inches too long), add fittings to both ends, and attach it to the old work box. Tie the other end to the top end of your cord (tie it to the wires, not around the BX armor) and pull the wires into the box below. Fiddle with the BX until the fitting goes through the knockout (you did pre-check to see that it was the right size, right?) and then fiddle the lock nut onto the fitting.

    Now you need only put the old work box into the opening and wire everything up. You should "pigtail" the wires in the box below, vs using just the outlet screws for all your connections.

    God is REAL, unless explicitly declared INTEGER
    1. Scott | Jan 14, 2009 11:13pm | #3

      >>>If you're using BX this may be the Chicago area where they're still worried about cows and lanternsHuh? There's got to be a story behind that statement.Scott.

      1. calvin | Jan 14, 2009 11:15pm | #4

        There's a heck of a story.

        Google Mrs O'Leary's Cow.A Great Place for Information, Comraderie, and a Sucker Punch.

        Remodeling Contractor just outside the Glass City.

        http://www.quittintime.com/

         

        1. Scott | Jan 14, 2009 11:18pm | #5

          Oh, THAT story......Hot time in the ol' town tonight.....Scott.

  2. User avater
    CapnMac | Jan 14, 2009 10:18pm | #2

    Well, it seems like I found this sort of DIY work all of the time.

    Mostly, the work is fishing the new cable down to the outlet, then pigtailing the black, white, & green together and making up the connection.

    Now, before all the electrical types load brickbats into their pitching machines, in hte above, I'm referring to what I have found in DIY work, not what good practice should or ought to be.

    In good practice we'd start with a good "map" of the existing circuits, and what is connected to them.  That would let a person examine the loading on the circuits, and see if there is "room" to add a fixture.  A good circuit map would also represent a good survey of the existing electrical, noting things like known conductor sizes, existnce of grounds, etc, too.  It would also include a switching diagram, too.  (Which can help either discover or prevent finding a switch in a loop of outlets <arrgh>.)

    Putting this sconce on a circuit with 15-20 fully-used outlets is much different than if there are only 4-5 mostly unsued outlets.

    A really great circuit map also has notes for box size and fill, too.  Box fill being a highly-overlooked DIY situation.  Stopping to get a remodel box in is not difficult, but it does take a bit more "open" time.  Which is usually what one does not have when you have the Design Committee tapping a foot behind you for not being finished 15 minutes ago . . .

    Occupational hazard of my occupation not being around (sorry Bubba)
  3. Richie921 | Jan 14, 2009 11:56pm | #6

    First open the outlet box and see where the existing wires enter the box. If u have a knockout on top of the box that would be the easiest.  Just locate where u want the light, an cut out for a cut in gem box. Next, assuming u are in the same stud bay, open a knockout on top of the box and try to send a snake up the wall to the hole u cut. If u make it, strip the new bx and put a connector on it. Just make sure to remove the nut on the connector. Now attach the wire to the snake and pull it down into the box.  Remove the snake and put the nut on the connector.  Put the cut in gem on the other end and insert it into the hole in the wall and secure. Mount the light and make your splices in the outlet box. No damage to repair and a new light to boot :)

    1. sharcitect | Jan 15, 2009 12:20am | #7

      Thanks everyone for all the great info.Now just to find the time to get to the store and do the work...

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