Building Service Disconnect question

Discussion in 'Electrical Forum discussion & Blog' started by gtmoy, Jan 21, 2012.

  1. gtmoy

    gtmoy New Member

    Messages:
    2
    Location:
    San Antonio, TX
    I have kind of a strange question. Today I was working on a lighting timer and shorted it. The 20A breaker flipped and I figured end of story; however half the building lost power, so I called in the power company. When they showed up, the guy opened the service disconnect (Fusible, 240V, 1000A) and the bus bars that connect the utility to our side were almost all the way out. Me shorting the power was the straw that broke the camels back. 2 phases were completely disconnected and one barely hanging on. The handle was in the fully on position. He asked me if anyone had messed with it and I said no. He ended up taking a dead blow and hammering the bars back in. Anyways, my dad and I were kind of curious if maybe after 26 years, the bars just vibrated out, or if it was kids who were messing with the switch (they broke our timer box, so they could turn off the lights to the building). I wouldn't think it was vibration, because it took some effort to put the bars back in fully, so there is plenty of tension. Anyone ever seen some thing like this?

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    Last edited: Jan 21, 2012
  2. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Hammers can fix most anything, but I never used one in an electrical panel. Maybe time for a new fuse box. Or a breaker.
  3. ActionDave

    ActionDave Electrician

    Messages:
    345
    Location:
    Colorado
    Two possibilities that I can think of
    A. Someone was messing around at one time.
    2. The switch was opened and when it was closed the blades were not fully engaged at that time.

    Either could have happened days or years ago and not been noticed.
  4. DonL

    DonL Jack of all trades

    Messages:
    3,810
    Location:
    Houston, TX
    Dead shorting a circuit can cause strange things to happen.

    That is why it is best to kill power first.

    You are lucky that you did not get hurt.

    You Blew it. lol.
  5. gtmoy

    gtmoy New Member

    Messages:
    2
    Location:
    San Antonio, TX
    Don't worry, I had the power off and when I flipped the 20A, it instantly tripped. All guards and insulators in place, and i use a multimeter on every wire before starting work. As far as I know, the power was turned on 26 years ago (1986) and nothing's been touched since. When the utility guy opened the panel, it looked brand new. I mean zero dust on anything, everything was still "shiny" i.e. all insulators were crack free and flexible looking (again no worries, I stayed 2 ft away from the panel at all times). There was no burn marks or wear marks on the disconnect at all. Like it has never been cycled before. We have tenants flip breakers all the time, I wouldn't expect a "little" 20amp breaker kicking out a 1000A service disconnect. Anyways, just thought it was odd, I've never seen something like this before. Thanks for all the replies
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