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 Post subject: Incident Energy level as EEWP trigger
PostPosted: Tue Feb 28, 2012 1:40 pm 

Joined: Tue Jan 24, 2012 4:11 pm
Posts: 3
Hi
[INDENT=1]I think that is very clear that when you have energized exposed components (shock hazard) and you need to work on or near to, an EEWP is required, but, what if you guard those exposed components (shock hazard eliminated, but Arc Flash hazard still present), and you need to work NEAR TO (energized cables for example), as near as inside of the AFB (ie, working inside the cabinet doing some load side cable termination on a de-energized breaker surrounding by others energized breakers). Do you still need an EEWP or not?[/INDENT]
[INDENT=1] [/INDENT]


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PostPosted: Tue Feb 28, 2012 8:32 pm 
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Location: North Carolina
Read the definition of arc flash hazard and especially the notes attached. The key is whether or not you are interacting with the live (not energized) equipment. There are numerous examples in the tables where the 70E Technical Committee recognizes that the hazard is minimal (H/RC=0) such as working on 120 VAC wiring in an MCC bucket in 600 V class gear.

There are also numerous ROP's where this is discussed. For instance I recall someone on the 70E general committee making the statement more than once that "merely walking by" a panel (basically the same case you are describing) is not a significant arc flash hazard. Many different proposals have been submitted trying to say what you are saying and all are rejected with "agree in principal" status, indicating that we all agree but no one has come up with an acceptable way of wording it yet.

At this point, I've got to diverge a bit to describe two different cases. If the equipment being worked on is in fact de-energized so that you have achieved a safe working condition, it does not eliminate the need to do a hazard analysis for the task. Even though the equipment to be worked on is de-energized, there is still a requirement to wear appropriate PPE while testing for absence of voltage for instance. There is still potentially a requirement to apply cover up to the energized conductors, and perhaps to wear arc flash PPE if you may inadvertently cause an arc flash. However, no EEWP would be required. The point of the EEWP is an administrative control to limit the amount of energized work being done. This is as opposed to the job briefing which is to try to ensure that both a hazard analysis is being done, and the results are being utilized to do the job safely.

In the case however of doing energized work, then this would seem to suggest an EEWP is required. However in some cases such as working on a 120 VAC control circuit in a panel it may be possible to do so where the likelihood of an arc flash is remote, and the likelihood of a shock is also remote due to proper tool usage (insulated tools). In which case the act of actually de-energizing and re-energizing the other equipment in the working space is actually much more likely to cause an arc flash (because you are interacting with it) than leaving it alone. It may be justifiable on that basis. And you may want to consider whether an annual EEWP is acceptable for standard procedures such as working on 120 VAC control circuits, which many operations have taken to doing.


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