There has been a great deal of discussion regarding what equipment should have an arc flash warning label. The 2012 Edition of NFPA 70E states:

[INDENT=1]Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures and motor control centers that are likely to require examination, adjustment, servicing , or maintenance while energized...[/INDENT]

This is obviously not an all inclusive list and open to interpretation.

I have been asked by several people to explore this further using the Question of the Week. I don’t think this can be done with one question, so beginning this week, there will be a series of questions regarding equipment labeling.

Hopefully this will help provide guidance to those that are unsure about how far to carry the arc flash study / labeling. There has also been some good discussion elsewhere in this forum.

If you have a specific question you would like asked as part of this next series, please let me know.

Here is this weeks’ question - the first in a series.

Which disconnect switches should have an arc flash warning label?

• Fusible disconnects 50 to 300 volts
• Fusible disconnects 301 to 600 volts
• Unfused disconnects 50 to 300 volts
• Unfused disconnects 301 to 600 volts
• It depends (please explain)
• No labels necessary

SELECT ALL THAT APPLY

Your thoughts and comments are encouraged and welcome.

It is all about risk.
If the equipment will be opened, not just operated, the employee should be advised of any known hazards.

It only makes sense to know where the disconnect is fed from, what upstream protective devices there are (if any), what the voltage to the disconnect is, and what the HRC is. It seems to be a logical extension of the list in NFPA 70E.

I`m very interested in everyone`s response to this question. I have been in the electrical trade for over 35 years and feel strongly that the potential arc flash hazards of a 30A/240V disc. would be so minimal that I feel like running a complete analysis on all of them in most facilities would be a waste of time and money. For example some of the small distribution facilities I`ve worked in it would mean doing a total analysis on 200-300 items instead of 40-50. In almost all situations the only thing you can do with a disc. live is check for the presence of voltage which would be covered under NFPA 70E table 130.7. Personally I feel that any disc. 100A or larger do have enough potential arc flash hazard to run a complete analysis on them. And I do think that all disc. should be marked as being a potential shock hazard but I`m leaning towards a somewhat generic label for all smaller disc. stating HRC 1 should be worn for voltage testing on 240V disc. and HRC 2 for 600V or less as per table 130.7.

Table 130.7(c)(9) indicates a hazard risk category for each of these instances based on that one could simply label teh device with an HRC requirment equal to that in the table without the need for an extensive detailed analysis.