Motor Disconnects

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dvcraven0522!

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St. Louis
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Electrical Design
I am working on a gran elevator project. Class 2 Division 1 environment.

n essence we are bring all motor controls and starters up to code. We are planning to provide a new MCC in "Dog House" on the roof of Bin floor and feed motors below with local start/stop. All starters and disconnect will be located in the MCC no local disconnects.

If I understand the code no local disconnects are required if supervised and disc/starter is able to be lockable in the open position. Is that correct?

Thanks
Dan Craven
 
I believe that is correct. However, there might be an advantage for future maintenance personnel if each motor does have a local disconnect. Otherwise, they would have to trudge up and down to the MCC, perhaps even several times for a single job, in order to lock out the motor. Just worth a quick thought.
 
There are several Exceptions permitting LOTO throughout Sections 430.102(A)&(B). They have two key principals:

  • A disconnect must actually interrupt or isolate the motor’s current [Section 430.101]; i.e., a disconnect is not a pushbutton or similar control device in the motor’s control circuit. Locking out a control device does’t cut it. Section 430.109 lists recognized disconnecting means.
  • A local disconnect cannot introduce an increased hazard. In Classified locations this is because someone may attempt to stop a running motor by opening the local disconnect rather than with the controller. Section 430.102(B)(2)(1) IN No.1 lists a few other non-exclusive examples.
 
charlie b said:
I believe that is correct. However, there might be an advantage for future maintenance personnel if each motor does have a local disconnect. Otherwise, they would have to trudge up and down to the MCC, perhaps even several times for a single job, in order to lock out the motor. Just worth a quick thought.
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Yep, and sometimes they may NOT trudge up and down to the MCC. Make safe activities easy for the employees to do.
 
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