Short Circuit

Discussion in 'Homework Help' started by waynebashan, Mar 27, 2006.

  1. waynebashan

    Thread Starter New Member

    Mar 26, 2006
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    If water gets in the main electrical panel, should the short or spark cause a fuse or breaker to blow?
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    I don't think that pure distilled water is a very good conductor. What causes a problem is all the rest of the stuff disolved in the water.

    Let's say the fuse/breaker is placed in the hot lead. I see three possible conditions.

    1. Input side of the fuse is shorted to neutral. The fuse and the load survive.
    2. Output side of the fuse is shorted to neutral. The fuse blows, but the load survives.
    3. Both sides of the fuse are shorted to neutral at more or less the same time. The fuse and the load survive.

    Once the water gets in and does its mischief, there is another problem as the water and its impurities are removed.
     
  3. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Easy answer is maybe. It would depend on the impurities in the water and how dirty or dusty the electrical panel is. If it is dusty then it will turn to "mud" and current wil flow. Depending on where the short is will determine if the fuse or breaker will blow. If the short is on the load side then yes it will blow. If it is on the supply side it may just fizzle until the mud dries out and the short may go away. It may also pop a street fuse if the short is big enough.
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
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    Where in the electrical panel? And how much water? A wee bit running over the ground bus and touching nothing else will make no difference. An ample stream across a phase will cause much consternation.

    As noted previously, distilled water insulates. Seawater conducts pretty well.
     
  5. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Have to be a little carefull with that comment. Distilled water will only insulate if it doesn't come into contact with contaminants which most electrical power boards over a day old will be full of. Dust, dirt and oxides will all cause the distilled water to become un pure and will increase its conductivity.

    There was a show on TV here a few weeks ago that showed a TV being lowered into various liquids. Distilled water was one, plain tap water was another and vegetable oil was the last. The TV expolded in the 2 waters but worked perfectly well submerged in oil.
     
  6. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    There have been oil filled capacitors and oil filed transformers in use for years ... well, until they decided that PCBs were bad.

    Distilled water has been used to cool high power transmitter tubes since the 60s. Each waterjacket surrounding the tube had a leakage current meter to keep an eye on when to change the water filters.

    Personally, I think if your main electrical panel were submerged, it would blow the main breaker and the utility company's fuse on the pole outside.

    Of course I've seen wind cause line slap, killing power to my facility a time or two [thankfully we had backup generators for that facility]. I also had a lightning strike blow up the 600 kW transformer outside that facility too.
     
  7. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    I used to work on 10KW HF transmitters. We used to use chicken sticks to ensure capacitors were discharged after removing power. This was done by running the chicken stick down the 3 50A fuses in the power supply. Generally it is very uneventful. One fellow worker one day forgot to switch the power off so when he ran the chicken stick down the fuses (415V 50A) the stick vapourised and popped all the fuses. One of the fuses exploded and the end shot out of the power supply and embedded itself in his thigh.

    OUCH

    He didn't do that again.
     
  8. waynebashan

    Thread Starter New Member

    Mar 26, 2006
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    This occured at work. Water entered the Main switch board and caused a short in one of the sub-panels, it popped and sparked a dozen or more times over several minutes. Finally the Electric company showed up and removed the power at the transformer. It never tripped the main breaker. After investigating the situation it was discovered that two of the three fuses at the transformer went out, two of the three fuses in the sub-panel blew and that same sub-panel was so hot that it melted the metal incloser. The whole time prior to the Electric company showing up we had one leg with power.
     
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