Six questions about Arc Flash Compliance and Analysis

Here are six questions about Arc Flash Compliance and Analysis. Please comment.

1. Is PPE required to pull a simple disconnect switch to de-energize an enclosure with the cover closed?

2. After an enclosure is de-energized by pulling the disconnect, is PPE required to test and verify the absence of voltage?

3. Pulling the disconnect switch on an enclosure de-energizes all the downstream circuits inside the enclosure. The incoming power to the switch contacts are still live. Therefore, Is the enclosure considered to be still energized or is it de-energized? How do other companies handle this problem?

4. Are gloves required for Hazard Categories 0 and 1? NFPA 70E Table 130.7(C)(10) is not clear regarding use of gloves for Hazard Categories 0 and 1. Are gloves required for shock hazard, even if they are not required for Arc Flash Hazard? If so, what type of gloves are acceptable for shock hazards?

5. Installing or replacing Bus Plugs on an energized Busway. I assume this is an example of live work requiring a work permit. Some people may disagree. Please provide clarification.

6. Do you know how other companies handle 480 Volt arc welders for their Arc Flash Study? We have a significant number which may affect our results.

I'll take a stab at some of them.


1. Is PPE required to pull a simple disconnect switch to de-energize an enclosure with the cover closed?

NO, Arc Flash is about working on or near exposed live parts. Behind closed metal covers nothing if required. However, some areas of the PPE risk table have PPE requirements for working with covers in place. But I think the general consensus is that behind a metal cover, Arc Flash does not apply.

2. After an enclosure is de-energized by pulling the disconnect, is PPE required to test and verify the absence of voltage?

I would say YES. Disconnects sometimes fail and the blades do not fully open and disconnect. You should never assume power is off until its verified with a voltmeter. The assumption has to be that power is present until proved otherwise, so you need PPE for the verification.

3. Pulling the disconnect switch on an enclosure de-energizes all the downstream circuits inside the enclosure. The incoming power to the switch contacts are still live. Therefore, Is the enclosure considered to be still energized or is it de-energized? How do other companies handle this problem?

This depends on the distances but under most conditions I would say it is live. If you could install a isolation barrier and guard around the incoming lugs then you could make an arguement for no PPE. The concern here is that you could inadvertantly touch the live lugs. If you are working outside of the Restricted Approach, if I remember 12"@480V then you could do the work without PPE. But voltage checking to verify disconnect worked would be in PPE.

4. Are gloves required for Hazard Categories 0 and 1? NFPA 70E Table 130.7(C)(10) is not clear regarding use of gloves for Hazard Categories 0 and 1. Are gloves required for shock hazard, even if they are not required for Arc Flash Hazard? If so, what type of gloves are acceptable for shock hazards?
NFPA only goes down to Class 0 (1000V) gloves but I think ANSI and OSHA recognize Class 00 (500V) gloves. I think 500V is as low as it goes. There is also an allowance to work with gloves one class higher than required without the leathers, but then the gloves have to be tested before being used again. I also remember gloves being required within the Restricted Approach barrier, you can check the table for the distances.


5. Installing or replacing Bus Plugs on an energized Busway. I assume this is an example of live work requiring a work permit. Some people may disagree. Please provide clarification.

NFPA doesn't give you tasks for needing the Live Work. It provides allowance for long term standing permits (NFPA uses the example of 3 months) for routine live work. This would be part of your training policy. You decide what is routine versus what isn't. For example, I require permits for 1) hands or tools touching live bus 250V or greater, 2) inserting or removing MCC buckets or switchgear breakers, 4) all work above 601V. But we can do without permits (or use our standing permit) change fuses, voltage checks, install remove snap in breakers, land wires to "off' breakers and MCCs. You need a policy and to define when the permit is needed. I use 12 months for my standing permit duration, and then we require a refresher course for the electricians.

6. Do you know how other companies handle 480 Volt arc welders for their Arc Flash Study? We have a significant number which may affect our results.

Are you talking about the actual arc created when welding. If yes, then Arc Flash doesn't apply. Arc Flash is about preventing accidental injury caused by arc flashes from electric shorts, not from welding. Follow your normal wleding safety guidelines.

Message me if you want to go over anything specific or if I can help you with you getting your program started.

OK, here are some other answers