Chasing short on newly installed light circuit (also newly drywalled)

Discussion in 'Electrical Forum discussion & Blog' started by waderpro, Jul 11, 2011.

  1. waderpro

    waderpro New Member

    Messages:
    7
    Location:
    Washington
    I have power to the switch, but the moment I touch it to the load side of the lights (8 daisy chained cans), sparks and breaker pops.

    Before I accuse the drywaller of putting a screw through the wire somewhere, what other steps can I take to chase this down?

    Yes, all the drywall is up, taped, and painted.

    Thanks in advance.
  2. kreemoweet

    kreemoweet Member

    Messages:
    374
    Location:
    Seattle. WA
    Well, of course you'd want to make sure that the short is not located in any of the light fixtures first (the more likely case in my opinion). If not,
    you would isolate each segment of the daisy chain and test it for shorting. At least then you'd know approximately where to start pulling off drywall.
    If the drywaller put a screw or nail in the wire, then it's the electrician's fault for inadequately protecting the wires.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,054
    Location:
    Cave Creek, Arizona
    The most likely spot is the first light. Since the wire from the switch to the lights is probably a "white" one, it may be bundled into the white neutrals at that point.
  4. waderpro

    waderpro New Member

    Messages:
    7
    Location:
    Washington
    HJ, please explain further

    HJ,

    Thanks for replying...could you please explain a bit further.

    The power is coming in at the switch, and then out to the first can, and then daisy-chained. All the blacks to blacks and whites to whites.
  5. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,348
    Location:
    Cincinnati OH
    Look in the switch box,if it is single pole, then you have a feed to switch(line),then you have feed to can lights(load).You need to find which is line and load first,at the switch.Do you have a muti-meter?Pull the first can out and check how it is wired,you may have undo all the connections at the first can.Then test from that point,if that is not the cause then you will have to go down the (daisy chain) one by one.
    ? did you wire this or was it done by an electrical contracter?
    Last edited: Jul 12, 2011
  6. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Pretty hard for the drywaller to screw up if you used nail plates of the correct size or stapled the wire well up into the joist.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,054
    Location:
    Cave Creek, Arizona
    If it is done the way you indicate, then go to the first light and separate the white neutrals. Then try the switch. If it trips the breaker then the problem is in the wiring between the switch and the light, or the hot wire is shorting out in one of the lights. If it does NOT trip, then start reconnecting one neutral at a time, turning the switch off while you connect it and back on afterwards, until you find the one causing the problem.
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