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  1. Default Lightning arrester

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    K, we were changing out a goab switch the switch was a normal open between two Circuits there were arrestors on the arm above the switch which we were removing. I wanted to cut the ground below the switch to isolate the ground potential before we removed the high side of the arrestors and got in there and started removing jumpers and everything else. Can anyone tell me what was wrong with cutting ground first before removing high side of arrestors with a shotgun?

  2. #2

    Cool Don't trust arresters!

    I have been retired since 2010, after 45 years in the trade and a little rusty on things. I would prefer to lift the high side first just in case the arrester was not internally in good shape.. Just my opinion ,never trusted arresters. Be safe Jerry Gronbach, Retired JL A.E,P, Co.
    Grumpy

  3. #3

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    I can't think of a good reason why you would cut the ground wire of a lightning arrestor prior to lifting the top side with a shotgun stick. Just my 2 cents worth.

  4. #4
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    What were you isolating ground potential from? Retired after 43 years in the trade, I have never seen the ground disconnected from an arrestor before cutting the hi side. Like Charlie said, I see no reason to cut the ground first.
    "It is not the critic who counts:The credit belongs to the man who is actually in the arena" Teddy Roosevelt

  5. #5
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    Why cut the arrest or ground clear first? Its no different than making or breaking connections . Neutral connections are made first, then hots. Neutrals are disconnected last when isolating. The lightning arrestor will not do its job if you cut the ground clear. I agree with isolating the lightning arrestors while working in proximity, but do it right . In my 30 years I have never seen an arrestor ground cut clear first. What if the arrestor had some minor tracking across it?

  6. #6

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    I'm guessing Headhunters thoughts about cutting the ground on the arrestor might be to prevent the explosive disconnect on the bottom of the arrestor detonating if the internal MOV stack had degraded over time and was likely to be sensitive to voltage anomalies caused by switching in its vicinity.

    The failure mode of most arrestors is progressive degradation of the MOV (Metal Oxide Varistor) stack caused by shunting transients over time until they are passing enough current continuously to trigger their safety disconnect with a bang. (A slug of carbon heating a .22 shell in some.) That's why you occasionally get an arrestor failure when switching in their vicinity.
    Portable defibrillators were first invented to save the lives of linemen. Where's yours?

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