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# minimum less than.

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## 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.

That's a very poorly worded sentence.

### RE: minimum less than.

replace "minimum" with "no less than". in your case arc rating should be at least 29994, yes?

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

### RE: minimum less than.

(OP)
Did you mean 29996 perhaps?

#### Quote (rb1957 revision)

The arc rating must be no less than 4 cal/cm2 less than the estimated incident energy.

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

### RE: minimum less than.

yes, and yes, but maybe "ESL" ?

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

### RE: minimum less than.

(OP)
I have no second language, EOL. Or are you referring to the OSHA author?

"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.

Why would the arc rating of a face shield be required to be less than the estimated arc intensity? It should be greater than.

### RE: minimum less than.

(OP)

#### Quote (Compositepro)

Why would the arc rating of a face shield be required to be less than the estimated arc intensity? It should be greater 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 must be a minimum of 4 cal/cm2 less than the estimated incident energy.
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.

Essentially, x - 4 and 4 < x both translate to 4 less than x.
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).

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