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 Post subject: disconnects
PostPosted: Sat Mar 16, 2013 1:29 pm 
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Can a operator in a (3phase 480 system) be allowed to turn a non-fusible water tight disconnect off to motor?


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PostPosted: Sun Mar 17, 2013 12:00 pm 
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Location: Rutland, VT
What is the arc flash hazard for that disconnect? Does the operator have the correct PPE for the arc flash hazard? Has he been trained to read and understand what is on the arc flash hazard label?

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PostPosted: Mon Mar 18, 2013 3:42 am 
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Motor will not engerize without going thur a squence to start. No training for the operator or ppe. When replacing nozzles on seperators, they pull the machine apart. Lock out 5 or 6 disconnects on differnt motors to have system locked out. No flash arc tags on disconnects. If they can do this on 480, why can t they do a disconnect on a homginzer with a tag. Same 480 system(same amp draw-200,250, at start up) all frq drives in another panel-100ft away upstairs.


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PostPosted: Mon Mar 18, 2013 4:54 am 
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Is the line side of the disconnect still energized when it is in the off position? Is this disconnect between a variable drive and the motor? Makes a difference is operation but do you still have to test for de-energization prior to working on motor or just try to start it?

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PostPosted: Mon Mar 18, 2013 7:24 am 
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wes hardin wrote:
Motor will not engerize without going thur a squence to start. No training for the operator or ppe. When replacing nozzles on seperators, they pull the machine apart. Lock out 5 or 6 disconnects on differnt motors to have system locked out. No flash arc tags on disconnects.

Many companies have 'mechanical' LOTO procedures that cover this situation which do not require PPE. Their reasoning is based on the frequency of operation of the disconnects means they are 'properly maintained' and that this specific operation is 'not likely to cause an arc flash'.
If the operator is trained in this operation, per OSHA they are qualified. Your Safe Work Practices program is between your company, OSHA, and the US legal system. NFPA70E does not specifically prohibit this procedure.


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PostPosted: Mon Mar 18, 2013 2:08 pm 
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wbd wrote:
Is the line side of the disconnect still energized when it is in the off position? Is this disconnect between a variable drive and the motor? Makes a difference is operation but do you still have to test for de-energization prior to working on motor or just try to start it?

yes, the disconnect is between the freq drive and motor. No pre -test to see if motors start. If have to select what product u are running and what tank you are coming from and going to. A squence (program ) is pulled down to start system. Disconnects have feed -back on them and will not let program start. wes


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PostPosted: Mon Mar 18, 2013 2:14 pm 
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JBD wrote:
Many companies have 'mechanical' LOTO procedures that cover this situation which do not require PPE. Their reasoning is based on the frequency of operation of the disconnects means they are 'properly maintained' and that this specific operation is 'not likely to cause an arc flash'.
If the operator is trained in this operation, per OSHA they are qualified. Your Safe Work Practices program is between your company, OSHA, and the US legal system. NFPA70E does not specifically prohibit this procedure.

I see now , where u are coming from. Since the power is off to the disconnect, unless the drive is on, should be no hazard,unless turned off while drive is on and motor running.


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