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Labeling Motors and Disconnects
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Author:  jghrist [ Fri Jun 10, 2011 5:52 am ]
Post subject:  Labeling Motors and Disconnects
Should utilitization equipment like motors or motor disconnects be labeled?

NEC says in article 110.16, "Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centers that are in other than dwelling occupancies, and are likely to require examination, adjustment, servicing, or maintenance while energized, shall be field marked to warn qualified persons of potential electric arc flash hazards.

Servicing or maintaining motor terminals won't be done while energized, but you have to have proper PPE to test for voltage. You may have to operate disconnects while energized, but is labeling and wearing PPE required if the disconnect door remains closed?
Author:  cbauer [ Fri Jun 10, 2011 6:05 am ]
Post subject: 
jghrist wrote:
Should utilitization equipment like motors or motor disconnects be labeled?

Servicing or maintaining motor terminals won't be done while energized, but you have to have proper PPE to test for voltage. You may have to operate disconnects while energized, but is labeling and wearing PPE required if the disconnect door remains closed?


At our facilities we put AF labels on disconnects. How else would a qualified person know what PPE is required to verify an electrically safe condition?
Author:  JJH [ Fri Jun 10, 2011 7:14 am ]
Post subject: 
We label disconnects but not motors.
Author:  jghrist [ Sat Jun 11, 2011 8:01 pm ]
Post subject: 
Thanks for your responses. I think labeling disconnects is the best procedure, with the understanding that voltage testing at the motor needs the same PPE as labeled at the disconnect.

If the IE at the motor is higher than at the disconnect, then I'd label the disconnect with the higher IE. This would be rare, but possible if the cable from the disconnect to the motor added enough impedance to reduce the arcing current to below an instantaneous trip setting.
Author:  glen1971 [ Sun Jun 12, 2011 10:32 pm ]
Post subject: 
JJH wrote:
We label disconnects but not motors.


I don't think I've ever seen a motor label, nor would I ever label one.. The labels wouldn't stand up to the conditions the motor is in, and there should be no live testing at the motor in the field, as they are not intended for it..

Especially on motors where the leads are taped, I wouldn't want to be cutting off the tape without knowing for sure that it was properly locked out already...That would be a good recipe for an incident report...
Author:  jghrist [ Mon Jun 13, 2011 7:26 am ]
Post subject: 
glen1971 wrote:
Especially on motors where the leads are taped, I wouldn't want to be cutting off the tape without knowing for sure that it was properly locked out already...That would be a good recipe for an incident report...

Good point about the taped leads. How would you test for voltage? Would you open the disconnect door and perform the voltage test there?
Author:  cbauer [ Mon Jun 13, 2011 9:14 am ]
Post subject: 
jghrist wrote:
Good point about the taped leads. How would you test for voltage? Would you open the disconnect door and perform the voltage test there?


As long as the disconnect is in line of sight of the motor, I would do my voltage testing at the disconnect. Otherwise, I would test at the disconnect with a volt meter and then again at the motor with a "tick tracer".
Author:  glen1971 [ Mon Jun 13, 2011 8:45 pm ]
Post subject: 
cbauer wrote:
As long as the disconnect is in line of sight of the motor, I would do my voltage testing at the disconnect. Otherwise, I would test at the disconnect with a volt meter and then again at the motor with a "tick tracer".


After the meterring in the starter/breaker and before the "tick tracer" I would try to start the motor by testing the Control Station (On/Off or Hand/Off/Auto) to ensure it doesn't start in the event of mislabelling or the wrong breaker being locked out.. Too many places have poor or no labels on equipment and switches.
Author:  cbauer [ Tue Jun 14, 2011 8:28 am ]
Post subject: 
glen1971 wrote:
After the meterring in the starter/breaker and before the "tick tracer" I would try to start the motor by testing the Control Station (On/Off or Hand/Off/Auto) to ensure it doesn't start in the event of mislabelling or the wrong breaker being locked out.. Too many places have poor or no labels on equipment and switches.


You are correct glen1971. Trying to re-start afetr disconnecting is part of our LOTO program.
Author:  Hawkeye23 [ Thu May 03, 2012 1:35 am ]
Post subject: 
I was told by a af person that they don't label disconnects unless they have fuses in them. right or wrong ?
Author:  JJH [ Thu May 03, 2012 5:49 am ]
Post subject: 
Hawkeye23 wrote:
I was told by a af person that they don't label disconnects unless they have fuses in them. right or wrong ?

They are wrong. There are no exemptions for non-fused disconnects. We label fused and non-fused disconnects.
Author:  PaulEngr [ Sat May 05, 2012 3:51 am ]
Post subject: 
cbauer wrote:
As long as the disconnect is in line of sight of the motor, I would do my voltage testing at the disconnect. Otherwise, I would test at the disconnect with a volt meter and then again at the motor with a "tick tracer".


I don't understand this. You have all 3 leads in one place, and it's shielded by the grounded enclosure. If you read your "tick" manual it becomes abundantly clear that:

1. They are not accepted devices for testing for absence of voltage.
2. They will give false negatives frequently in the scenario you are talking about.
Author:  PaulEngr [ Sat May 05, 2012 3:52 am ]
Post subject: 
Hawkeye23 wrote:
I was told by a af person that they don't label disconnects unless they have fuses in them. right or wrong ?


Frequently if cable impedance is very low or ignored, they don't MODEL them because the disconnect does not affect arc flash. This has nothing to do with whether or not it needs a label.
Author:  jcampbell [ Thu May 17, 2012 7:56 am ]
Post subject: 
It sounds to me like you have two separate situations.
1) If you are servicing or maintenancing then you are 100% in LOTO by OSHA. Per OSHA, you do have to test for the abscence of voltage:
1910.147(d)(6)
[INDENT]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.[/INDENT]
I understand that there may be a troubleshooting issue that there has to be live voltage on the motor and NFPA 70E will give you guidance on tackling that. Basically, you should wear the PPE which is required at the upstream palnel/disconnect from the motor. You do not have to label the motor but it should be a "Work Practice" implemented at your site for situations like these and should be included in your electrical safety training. Both of these should be documented somewhere to help you in a legal sense and meet the requirements of the electrical safety program in 70E.

2) If the disconnect can create an arc flash defined by NFPA 70E then yes, if you are "interacting" as operating a disconnect then it must be labeled and specific PPE per the Hazard Category must be donned. An example would be to review the first section of NFPA 70E 2012 Table 130.7(C)(15)(a) where it talks about HRC 0 for fused switch operation with covers on at 240 and below.
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