Two simple words, a total of six letters, help define which electrical equipment is required to have an arc flash label. Although these two words are used with good intentions, they can often leave a person second-guessing themselves.
The words “such as” can be found in the 2012 edition of NFPA 70E, Standard for Electrical Safety in the Workplace: “130.5(C) Equipment Labeling. Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers ...” (emphasis added).
What if I have equipment that is not on the list? Since only five types of equipment are included, this is a common question. The list was never intended to be all-inclusive but rather to provide examples of the possible types of equipment that may require an arc flash label.
Further guidance is provided by the additional language of Section 130.5(C), which states: “... and are likely to require examination, adjustment, servicing or maintenance while energized” (emphasis added).
The “likely” language is designed to help determine whether equipment not found on the list should have a label.
Survey—what would you label?
Since there is some judgment involved with the “likely” language, people will have different views on which equipment does and does not require a label.
To gauge how the “likely” language is interpreted, I asked a series of questions at www.ArcFlashForum.com regarding omitted equipment. Each week, a new question focused on a specific type of equipment with various multiple choice answers about labeling. Each question is listed here along with the results.
As in past survey questions (see “It’s a Gray Area,” www.ECmag.com/jp0712), this is far from a scientific survey and is not meant to provide any formal interpretation about Section 130.5(C). Rather, it is to offer a bit of insight into opinions about equipment labeling.
For the first two week’s questions, the total does not add up to 100 percent because more than one answer could be selected. The values shown are the percentages of total respondents. The results of the other five questions all add up to 100 percent.
Week one: Disconnect switches—by voltage and fused vs. unfused
Which disconnect switches should have an arc flash warning label?
• Fusible disconnects 50 to 300 volts (V) 67%
• Fusible disconnects 301 to 600V 76%
• Unfused disconnects 50 to 300V 44%
• Unfused disconnects 301 to 600V 65%
• No labels necessary 2%
Week two: Disconnect switches—size and fused vs. unfused
Which disconnect switches should have an arc flash label?
• Fusible disconnects 100 amperes (A) or less 55%
• Fusible disconnects greater than 100A 70%
• Unfused disconnects 100A or less 32%
• Unfused disconnects greater than 100A 40%
• It depends 35%
Week three: DC equipment
Do you believe arc flash warning labels should be on direct current (DC) equipment/systems greater than 50V DC?
• Yes, using NFPA 70E HRC tables 38%
• Yes, using calculations 55%
• No 5%
• Other (please explain) 2%
Week four: automatic transfer switches
Do you believe arc flash warning labels should be on automatic transfer switches?
• Yes 95%
• No 0%
• It depends (please explain) 5%
Week five: 480V receptacles
Do you think 480V receptacles should have an arc flash warning label?
• Yes 27%
• No 44%
• It depends (please explain) 29%
Week six: variable frequency drives
Do you believe arc flash warning labels should be on variable frequency drives?
• Yes 75%
• No 5%
• It depends on the situation 20%
Week seven: wire ways/junction boxes
Should arc flash warning labels be placed on enclosures such as wire ways and larger junction boxes?
• Yes 13%
• No 52%
• It depends on the situation 35%
When in doubt
Many people also provided feedback. A recurring comment referred back to the “likely” language. When judging whether equipment not on the list should have an arc flash label, answer the following question: Will the equipment likely require examination, adjustment, servicing or maintenance and will this be done while energized? Although it is impossible to provide a list of every type of equipment that requires an arc flash label, using the “likely” language can provide the necessary guidance to help make the labeling decision.
About The Author
PHILLIPS, P.E., is founder of brainfiller.com and provides training globally. He is Vice-Chair of IEEE 1584 Arc Flash Working Group, International Chair of IEC TC78 Live Working Standards and Technical Committee Member of NFPA 70E. He can be reached at [email protected].