An Arc Flash calculation for a 480V switchboard has been done according to IEEE 1584 standards. The Hazard Risk Category has been determined to be Class 3. When going up to the switchboard to read the volt meter and ammeter, using the associated swithces, is Class 3 clothing required or can a lower classification clothing be worn?
Arc Flash Classification & Meter Reading
- Thread starter Lewis F
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zog
Senior Member
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- Charlotte, NC
IEEE 1584 does not use HRC's, those are from the tables in NFPA 70E so I am a little confused what the person who did the study is thinking. The calulated Ei should be on the enclosure door. That calulated Ei is the hazard that has been determined for that enclosure and the proper PPE needs to be used anytime you are "interacting" with the equipment in such a way an arc flash may occur. After the study is done it is all or nothing, you cannot use reduced PPE from the 70E task tables.
So your real question should be, does operating a switchboard mounted voltmeter fall under the definition in the 70E of "Arc flash hazard". You won't find a clear cut answer in the standard (Yet) so your facility will need to make a judgement call on that one.
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