Arc Flash Category 4 and 4+ ?
Arc Flash Category 4 and 4+ ?
(OP)
I was hoping to get everyones help on this. I see that several manufacturers offer arc suits up to 100 cal/cm^2 but my understanding of the NFPA70-2004, Table 130.70(c)(11) is that anything above 40 cal/cm^2 can not be worked on energized.
My understanding is at above 40 cal/cm^2 the blast itself will kill you - not necessarily the arc.
So how do I handle a location that is 85.2 cal/cm^2 until the engineering solution is implemented?
Am I confused? Any comments will be appreciated. Thanks.
My understanding is at above 40 cal/cm^2 the blast itself will kill you - not necessarily the arc.
So how do I handle a location that is 85.2 cal/cm^2 until the engineering solution is implemented?
Am I confused? Any comments will be appreciated. Thanks.






RE: Arc Flash Category 4 and 4+ ?
If you can describe the equipment maybe I can help you with your problem.
RE: Arc Flash Category 4 and 4+ ?
As I said, this was my understanding and I wanted to get a sanity check with what everyone else is being told or is telling clients about levels >40 cal/cm^2.
Our consultant has told me that no one can go near the switchgear until we reduce the levels to below 40 cal/cm^2.
RE: Arc Flash Category 4 and 4+ ?
Ther are several solutions depending on your equipment type and configuration that you could have implemented over this weekend. We would nevr leave our clients in a situation like that. What happens if you have a breaker trip tonight? I am sure the production boss would love to hear "Sorry we cant turn anything back on, the consultant said to stay away"
Scott Peterson
Training Manager
Power Plus Engineering
www.epowerplus.com
RE: Arc Flash Category 4 and 4+ ?
RE: Arc Flash Category 4 and 4+ ?
De-energize it.
RE: Arc Flash Category 4 and 4+ ?
RE: Arc Flash Category 4 and 4+ ?
RE: Arc Flash Category 4 and 4+ ?
RE: Arc Flash Category 4 and 4+ ?
It is very simple, if you are so worried and caring about someone's life do not work live. Arrange and design redundant systems. OR some risk in life are necessary, but I would not ask someone to risk his/her life for saving anyone's any amout of money or equipment.
There are many much less risky ways to determine if the equipment are deenergized.
RE: Arc Flash Category 4 and 4+ ?
My point exactly. If the assumed working distance was 18", you can re-run the numbers to find the Ei at the actual working distance. For example if you want to use a remote racking system, a remote breaker operator (Like the chicken switch), or a hot stick for verifing a system de-energized you may find the Ei is less than 40 cal/cm2.
RE: Arc Flash Category 4 and 4+ ?
RE: Arc Flash Category 4 and 4+ ?
However, some companies do require PPE to be worn when entering some electrical rooms - that is a company safety policy, but not required by NFPA 70E - at least not yet.