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Thread: Disconnect Can Be Opened Live

  1. #1
    Join Date
    Jun 2005
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    Disconnect Can Be Opened Live

    I see lots of motor disconnect enclosures that can be opened with the switch ON and I see lots where the enclosure can't be opened with the switch ON.

    Are there any code requirements that prevent a switch enclosure from being opened while the switch is ON.

    If there are, when did this requirement take effect?

    I have a customer that had a residential elevator fail its annual inspection in Mass because the switch could be opened with the switch contacts in the closed position.

    There is a code requirement (NEC 620-51(A)) that the switch be lockable in the open position but that is not what was cited

  2. #2
    Join Date
    Mar 2010
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    Quote Originally Posted by mkgrady View Post
    because the switch could be opened with the switch contacts in the closed position.
    620.4?

    Could be that the disconnect is accessible by anyone or clearances were not maintained and none of 620.5 were met?

    620.5 may be in the weeds a bit.

    #PrudentPrePlannigPreventsPissPoorPerformance

  3. #3
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    Its more of a UL listing issue than the NEC.
    Moderator-Washington State
    Ancora Imparo

  4. #4
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    Oct 2013
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    newburgh,ny
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    been many years

    It has been many years since I saw one the you could open when on, is it just dirty and needs cleaning or is it that old?
    A cowboy may get thrown , but they always get up and walk forward.

  5. #5
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    Quote Originally Posted by just the cowboy View Post
    It has been many years since I saw one the you could open when on, is it just dirty and needs cleaning or is it that old?
    I have not seen it. I just looked at a couple of manufactures catalogs (Siemens and Square D) that are several years old and it appears you could still buy a disconnect without the door interlock in the smaller sizes. My customer just does not want to change the switch unless he is violating the NEC or some other code. He might even change the switch to one with the interlock down the road but he feels like he is being forced to do something that is not enforceable by any code. The cost is not the issue. I told him to get a chapter and verse of the requirement from the inspector.

  6. #6
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    Nov 2016
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    Dublin, GA
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    Don't know if they are still manufactured that way, but there are literally millions of MCC starter doors that can be released with a screwdriver or similar tool while energized. You can also close the switch/breaker with the door open. Such capability is viewed as almost a troubleshooting necessity in heavy industry. In those cases, however, it is an intentional act that someone has to know how to perform.

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