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Thread: LOTO molded case breaker

  1. #1
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    LOTO molded case breaker

    Looking for opinion on using a molded case breaker for a lockout? My question concerns an operator throwing a disconnect with a molded case breaker to shut off the machine to clear a jam. Typically if we are doing any electrical work we check to make sure the power has been removed, but since we are not doing any electrical work do we still need to check to make sure the breaker opened or can the operator try to start the machine and if it does not start they are safe to clear the jam? I'm old school and I would want the power checked before I stuck my hands in? How do other folks accomplish this? Looking forward the replies!

  2. #2
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    Quote Originally Posted by cornbread View Post
    Looking for opinion on using a molded case breaker for a lockout? My question concerns an operator throwing a disconnect with a molded case breaker to shut off the machine to clear a jam. Typically if we are doing any electrical work we check to make sure the power has been removed, but since we are not doing any electrical work do we still need to check to make sure the breaker opened or can the operator try to start the machine and if it does not start they are safe to clear the jam? I'm old school and I would want the power checked before I stuck my hands in? How do other folks accomplish this? Looking forward the replies!
    Regardless of code/regulations, I'd want it locked off with the key in my pocket before I stuck my hands in there.
    Si hoc legere scis nimium eruditionis habes.

  3. #3
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    Ask yourself what the danger might be, if someone were to reclose the disconnect while a person is trying to clear the jam. In a purely electrical environment, if you have your hands inside an electrical component and someone recloses the power supply breaker, the danger is that you might get a shock (or worse). An LOTO is certainly necessary for that situation.

    But it sounds like you are describing a different situation. I might want to know whether any motor would automatically restart and possible trap the worker's hands or clothing on a rotating piece of machinery, if someone were to reclose the disconnect. I might also want to know what it would take to "clear the jam." I have cleared paper jams from large office copiers without turning them off or unplugging them. In that situation I don't believe there is any danger that the copier would start operating until the jam is cleared and the reset button is pushed. But if clearing the jam requires tools and time and disassembly of machine components, it becomes a different situation.

    The bottom line is still that safety outranks production. I don't know what OSHA rules would have to say, but I think at a minimum the person reaching in to clear the jam should put their own lock on the disconnect and hang on to its only key. I agree with Besoeker on this point. A tag-out might or might not be a necessary additional step, depending on the nature of the task.
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.

  4. #4
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    Operations would use a personal lock to assure the disconnect can not be closed. My concern is how do you verify the breaker opened, the disconnect mechanical did not fail.... unless you verify with a meter the circuit is de-energized.

  5. #5
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    Found this searching this forum

    http://forums.mikeholt.com/showthread.php?t=105691


    NFPA 70E Lockout Requirements

    Our plant currently uses none-electrical personnel for many lockouts that do not require electrical work. Example would be a pump change. Here is a very basic procedure for a single point lockout:

    -Shutdown equipment
    -Open Disconnect at MCC and apply lock to disconnect
    -Attempt to start equipment
    -Perform work.

    Does NFPA 70E require a qualified person to verify absence or voltage for this type of lockout?

    Thanks


    Seem from this the thread the answer is yes... verification of absence of voltage.

  6. #6
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    We did it that way

    When I work for a large plant, when clearing a jam we did the following.

    Stop machine.
    Pull disconnect and listen for the clunk noise of it opening. ( yes it can still make noise and fail. )
    If jam was in arms reach AND line of sight of disconnect, a lock was not needed, if out of reach OR sight you HAD to lock it out.
    Check to see if machine will start with disconnect off, to check if blades opened ( Yes one leg may stay in).
    Clear jam, turn on disconnect, restart machine.

    That was for jam clearing ONLY, if maintenance had to work on it, it had to be locked out and verified power is off.
    A cowboy may get thrown , but they always get up and walk forward.

  7. #7
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    OSHA says for lockout/tagout the minimum requirements are to lock out the energy isolating device (MCCB in this case) and then verify isolation by attempting to operate via the controls.

    As always with anything safety related, you should do a hazard analysis.

    In our analysis, having personnel open a panel and expose themselves to arc-flash and electrical hazards was MORE of risk than the MCCB failing in such a manner that the machine would not operate when tested but could be operated by some other means or circumstances.

    Zero voltage verification is only done when doing work that would expose personnel to electrical hazards.

  8. #8
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    Looks like OSHA 1910.147(d)(6)
    Verification of isolation. Prior to starting work on machines or equipment that have been locked out or tagged out, the authorized employee shall verify that isolation and deenergization of the machine or equipment have been accomplished.

    I guess trying to start the machine would be one way of verification. That's going to be a big shift in our thinking as we typically assume the machine needs to be placed in a electrically safe condition as defined by NFPA70E. It will be interesting to see how our safety folks handle this.

  9. #9
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    Quote Originally Posted by cornbread View Post
    Looks like OSHA 1910.147(d)(6)
    Verification of isolation. Prior to starting work on machines or equipment that have been locked out or tagged out, the authorized employee shall verify that isolation and deenergization of the machine or equipment have been accomplished.

    I guess trying to start the machine would be one way of verification. That's going to be a big shift in our thinking as we typically assume the machine needs to be placed in a electrically safe condition as defined by NFPA70E. It will be interesting to see how our safety folks handle this.
    As has been mentioned, verifying absence of voltage is important to electrical maintenance tasks, but "unplugging" a jammed machine isn't an electrical task. Is possible to clear this machine workers may need to turn off/lock out other energy sources such as steam, air, gas, etc.

  10. #10
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    I think sometimes the need to verify absence of voltage is not well understood.

    It is generally only needed when an employee would be exposed to energized parts.

    If it is just about motion, it would not matter any if one blade of a switch failed. There still would be no motion. However, there could be live electricity there just waiting to get someone that exposed themselves to it.
    Bob

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