tripping breaker

Discussion in 'Electrical Forum discussion & Blog' started by bcdudley, Jan 25, 2012.

  1. bcdudley

    bcdudley New Member

    Messages:
    15
    Location:
    Texas
    I have a 20 amp breaker that keeps tripping. I have replaced the breaker and that did not resolve the problem. The circuit was added after the house was built and the only thing on it is the sprinkler system timer and one of the large outdoor floodlights. I think it is a high pressure sodium light. The light has a photo cell, but it does not work. The breaker only trips when the light is left on for more than 48 hours and if the sprinkler system is turned on. I can leave one or the other on for an indefinite amount of time with no problems.

    The sprinkler system uses a dc brick and pulls a very small load. I think it is something like 24 watts and 800 milliamps. I do not know what the light pulls.

    Should I just split them up to different circuits, or do I have a different problem?

    Thanks.
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,560
    Location:
    North Carolina
    Without some testing it would be impossible to say if there was some other problem.

    Why would you leave that big light on in the daytime for? Do you like giving your money to the utility?

    It could possibly be the light if it is left on all the time.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,274
    Location:
    New England
    The gradual heat buildup from being on for a long time may cause something to expand and short, or the high voltage supply momentarily crap out and short the line. If that's the case, splitting the feeds wouldn't likely help.
  4. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,456
    Location:
    Houston, TX
    You may want to replace the photo Cell, but the ballasts may be toasted. That type of a fixture needs Much cooling and running 24/7 in the Texas heat and ON may have toasted the Transformer Windings and a arc-over may be blowing the breaker.

    A low voltage transformer can do that also, but it normally will melt its internal fuse, and just be dead.


    You should quit using that light until the problem is solved. I would have quit using it when the photocell quit working.
  5. bcdudley

    bcdudley New Member

    Messages:
    15
    Location:
    Texas
    The light was in the house before I moved in. It was hard wired to the breaker with no switch. I installed one a while back and keep it off 99% of the time now. I usually don't even turn it on at night unless I need it. The light is on a pole about 20' up in the air and the photocell is on top of the housing. I do not have an A-frame ladder that tall and have not had a chance to go rent one yet. I can see from the ground that the plastic cap that goes over the photocell is busted.

    Also, that doesn't explain why it only does it when the sprinkler system is on.

    I was going to replace the photocell this weekend, but I wanted to see if there was anything else I needed to do while I had the ladder and I was up there.
  6. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,456
    Location:
    Houston, TX
    You should be able to tell the rating by the bulb that it uses.

    Maybe you are at the breaker limit.
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