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#44380 - 11/02/04 06:59 PM Living with NFPA 70E
hypress Offline
Member
Registered: 07/20/04
Posts: 129
Loc: Charleston WV
Has anyone had any experience with NFPA70E the electrical safe work procedures and arc blast protection requirements.From what I have heard some of it is OK but some of it is way out in left field. Our plant has been useing flash suits for switching for years now 70E says you have to use flash suits any time you work on anything 100 volts or more.What is your alls take on 70E. THANKS.
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#44381 - 11/03/04 04:22 AM Re: Living with NFPA 70E
Big Ed Offline
Member
Registered: 04/07/04
Posts: 55
Loc: Roxboro, NC, USA
Hypress,
It is not as restrictive as that. It stipulates several levels of protection based on the work being done and the voltages present. Basically they have assumed the arc potential for many common jobs and setup the proper protection for each.

I would reccommend that you invest in some arc hazard analysis if you plan on fully implementing 70E, it will significantly lower most of the requirements.

The protection levels can be as low as all-natural fiber clothes up to the full arc suit with ballistic protection.

Good luck,
Ed
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#44382 - 11/03/04 07:03 AM Re: Living with NFPA 70E
Ron Offline
Member
Registered: 03/13/02
Posts: 582
Loc: White Plains, NY
In order to use the standardized table in NFPA 70E, you must know the calculated fault current at the equipment you will be working on, then calculate the arc flash fault current, then you can match that to the characteristic of the upstream protective deices (breakers and fuses), to see how long it will take to clear the fault. Then and only then can you attempt to use the table in NFPA 70E, if you fall within the parameters of the notes in the table.
I have found many incident energies higher than 40 or even 100 cal/cm^2, thus making any arc suit useless.
Don't forget the energized work permits required by 70E too
Good luck.
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Ron
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