Grounding

Discussion in 'Pro Audio' started by geoley, Nov 2, 2005.

  1. geoley

    geoley Guest

    I read the story about the church pastor electrocuted when he grabbed a mic
    while standing in water. I can see where this can happen. A guitarist friend
    of mine had an old guitar amp, I forget what make, and during a gig when his
    lips made contact with the mic he was singing into he got a helluva shock
    that darn near knocked him down. Later investigation of the amp revealed
    that the hot side of the line had gone to chassis ground via a defective
    bypass cap. The mic he was singing into was connected to the venues PA
    system which was at ground potential. Just shows what can happen

    George
     
    geoley, Nov 2, 2005
    #1
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  2. Should propper grounding and a safety switch (switching off mains when a
    leakage current of 30mA or so to earth is detected) be standard? In The
    Netherlands every instalation build or modified since 1975 should have
    this safety switch.
     
    Chel van Gennip, Nov 2, 2005
    #2
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  3. geoley

    Scott Dorsey Guest

    In the US, this safety switch is called a GFI (Ground Fault Interruptor)
    and it's been required for about 20 years in any wet environments. You
    will see them in bathrooms, and of course they are required on swimming
    pool (and baptismal font) heaters and pumps.

    But you won't see them in most stage environments, aside from outdoor
    stages. In part this is because they can trip too easily.

    Still, the problem mentioned above can be prevented by retrofitting a
    three-prong power cord onto the amp, which is something that EVERY
    amp should be equipped with today.
    --scott
     
    Scott Dorsey, Nov 2, 2005
    #3
  4. geoley

    mainmachine Guest

    this cap is referred to as the "death cap" for a reason!
    -daver
     
    mainmachine, Nov 3, 2005
    #4
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