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Thread: 138KV switching

  1. #11
    Join Date
    Feb 2007
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    Rob the only time I wear my class 4s is when I am actually rubber gloving 27, all other times class 2 at the most.

  2. #12
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    Yeah , Lewy, I am a firm believer in only wearing my rubber gloves when needed, especially my class 4's. It does make good sense to me to use them when operating an air brake or LIS though , but I only wear them when actually operating the handle, and I don't hang around the area when I am done, just in case it goes boom!

  3. #13
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    Feb 2009
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    Quote Originally Posted by rob8210 View Post
    Yeah , Lewy, I am a firm believer in only wearing my rubber gloves when needed, especially my class 4's. It does make good sense to me to use them when operating an air brake or LIS though , but I only wear them when actually operating the handle, and I don't hang around the area when I am done, just in case it goes boom!
    Rob, cant count the times getting ready to throw the switch and took a good look around and devised an escape route away. Nothing ever happened,(as if I was faster that lightening ) but in some cases the station gates were on the other side of the station behind the Transformer I was reenergizing. We didn't always have the option of a remote closing point especially on customer stations.

  4. Default

    You have had a lot of response to your question, but I will validate what "Thrasher" was trying to say. The reason you wear gloves, even those rated below the switched voltage, has to due with resistance.
    Ideally, the mat is at the same potential as the switch-handle (equal-potential). If you are within your equal-potential zone then no current will flow through your body (if your feet are at the exact same potential as your hands). However, if there is a compromised connection in the grounding, then the gloves would increase the resistance of current flow through you. Electricity takes the path of least resistance. Those 20kV gloves have a high-resistance value.
    You are correct, that 20kV gloves won't protect against 138kV, but you are not in series with the circuit. If something catastrophic happens during the switching sequence, then more than likely, it will find an alternate path to ground. Nothing in this world is certain, but at least you are putting forth an effort.
    Oh, and the statement about a few hundred volts on the handle is accurate too. Check your voltmeter; you might be surprised!

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    Thanks for additional inputs. Currently, we do not use a portable ground mat. Most of our 138KV switches are in transmission subs and are bonded to a ground grid. We have been assured that the grid provides sufficient grounding. However, I hesitate to trust the findings of the same group that inspected the ground grid at the failed 34.5 air break and deemed them "intact and in perfect working order". I'm still concerned with catastrophic failure of overhead hardware, porcelain, etc... Again, I saw all of this with the 34.5 failure and don't want me, or my co-workers in that "line of fire".

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