Arc Flash over 40 cal/cm2

[cvirgil467]

I have some equipment that is listed as "dangerous" and over 40 cal/cm2. My unsderstanding is that NFPA 70E-2012 does not explicitly prohibit work at locations with energy levels above 40 cal/cm2. Is that true that although dangerous per code it's not a problem so long as i have the proper PPE? Is there PPE that can be purchased to work on equipment over 40 cal/cm2? Is

Thanks.
b

 

[Fulthrotl]

I have some equipment that is listed as "dangerous" and over 40 cal/cm2. My unsderstanding is that NFPA 70E-2012 does not explicitly prohibit work at locations with energy levels above 40 cal/cm2. Is that true that although dangerous per code it's not a problem so long as i have the proper PPE? Is there PPE that can be purchased to work on equipment over 40 cal/cm2? Is

Thanks.
b

there is PPE up to 100 calorie arc flash level.

when i received my arc flash training from the public utility i worked for,
the trainer said that arc flash protection above 40 calories was not something
that they felt was necessary, as above 40 calories the pressure wave was
normally lethal. his exact words.

it's not the flash at that point, it's the kaboom.

if i need a level above 40 calories, i don't need a suit, i need a outage and
a lockout, or you need another sparky.

either one.

 

[fmtjfw]

there is PPE up to 100 calorie arc flash level.

when i received my arc flash training from the public utility i worked for,
the trainer said that arc flash protection above 40 calories was not something
that they felt was necessary, as above 40 calories the pressure wave was
normally lethal. his exact words.

it's not the flash at that point, it's the kaboom.

if i need a level above 40 calories, i don't need a suit, i need a outage and
a lockout, or you need another sparky.

either one.

The advantage of a 100 calorie arc-flash suit is that they may be able to find all the body parts in one place instead of scattered.

 

[jim dungar]

The advantage of a 100 calorie arc-flash suit is that they may be able to find all the body parts in one place instead of scattered.

Arc blast force is not related to incident energy. Our industry calculations are more about the 'area under the curve' and not 'peak energy'
There is probably almost as much chance of blast injury for a <8cal/cm^2 fault as there is from a >40 cal/cm^2 event.

Consider: what is the incident energy output for a 480V circuit with an available arcing fault current of 5000A and a clearing time of 20 seconds versus that of a 30,000A event and a .033 clearing time?