## minimum less than.

## minimum less than.

(OP)

## Quote (OSHA 1910.269 Appendix E referring to face shields)

The arc rating must be a minimum of 4 cal/cm2 less than the estimated incident energy.

So my estimated incident energy is 30000 cal/cm^2 for example. I must subtract a minimum of 4, so to be extra super conservative I'll just subtract the whole 30000; resulting in a face shield with no arc rating at all. Right?

## RE: minimum less than.

## RE: minimum less than.

another day in paradise, or is paradise one day closer ?

## RE: minimum less than.

Still ambiguous, since no order of operations is either expressed or implied.

## RE: minimum less than.

another day in paradise, or is paradise one day closer ?

## RE: minimum less than.

"The arc rating must be no less than the result after 4 cal/cm2 is subtracted from the estimated incident energy" I think expresses the intent.

## RE: minimum less than.

## RE: minimum less than.

A question I've asked in another forum. This deviates from NFPA 70E. My initial guess is that putting line workers in arc hoods in the weather was seen as too restrictive.

## RE: minimum less than.

The arc rating is x.

The estimated incident energy is y.

The arc rating must not be less than the estimated incident energy minus 4 cal/cm2.

x >= y-4

Another way to say it,

The arch rating must be greater than or equal to the estimated incident energy minus 4 cal/cm2.

## RE: minimum less than.

However the 4 < x interpretation can mean that you could end up with an impossible value (if the estimated incident energy was 0 or 1 or 2 or 3, the interpretation would yield a negative value, rendering this logic less robust than the first interpretation. You can also use human logic (such as, the first version is a safer interpretation).