Arc Flash Labels

[nmadhusudhan8@gmail.com]

Hi Everyone,

Do we need arc flash labels for capacitors installed at Motor. we have a 10KVAR capacitor at 40HP motor in the field and we are thinking to place a arc flash label at the capacitors. the reason for this is capacitors wont discharge immediately after the motor stopped working, in this case is it good to keep arc flash label on capacitors.

Thank you,
Madhu.

 

[charlie b]

Arc flash labels are only required for equipment such as panelboards, switchgear, and MCCs. The idea is that if a short circuit occurs within one of these, and if that creates an arc through the air that would itself be a short circuit path and would result in the release of lots of energy, the upstream energy source (e.g., the main service switchboard) would continue to feed energy into the arc until some overcurrent device opens and thereby terminates the event. The capacitors to which you refer can discharge their energy only once, that that briefly. They are not capable of establishing an arc of short circuit current through the air. So no, you don't need arc flash labels in that application.

 

[mayanees]

The only way you'd need labels at a capacitor is if the cap terminals could be accessed while energized, for inspection or troubleshooting.
John M

 

[charlie b]

You would not need labels even then. Take a look at 110.16. Motors are not on the list, nor are they anything close to being similar (i.e., they don't fit into the phrase "equipment, such as . . . .").

 

[jim dungar]

You would not need labels even then. Take a look at 110.16. . . .").

NEC 110.16 may not be the governing standard. In reality this situation may be better addressed under the NFPA70E standard and the company's Electrical Safe Work Practices program.

OSHA requires you to protect your workers from known hazards. How is an employee supposed to select the correct PPE, if there is no advisory information on the equipment?

 

[petersonra]

I saw one one a welding outlet today. Arc flash hazard radius of 5 inches.

 

[kwired]

As Charlie said the arc flash hazard is not there unless you are doing something while the line is energized.

If anything you may want a label warning that voltage may be present even after source voltage has been disconnected, even though a qualified person should already know this. I don't believe the NEC addresses any warning sign, but 460.6 does require discharge to less than 50 volts within 1 minute after capacitor is disconnected from supply.

If capacitor is connected to motor even when disconnected from power it probably discharges through the motor nearly instantaneously.