This week’s question is a continuation about the use of alternate methods and exceptions for incident energy calculations and PPE selection.

During the past few weeks there were questions revisiting the IEEE 1584 “2 second rule� and the “125 kVA transformer exception�

This week is about another IEEE standard. IEEE Standard C2 – National Electrical Safety Code – 2017. This standard contains Table 410-1 Clothing and clothing systems for voltages 50 V to 1000 V (ac). Without going into detail about this table (that will be coming a bit later) this week’s question is simple.

Do you consider NESC Table 410-1 as a viable method for selecting PPE?
Yes
No
Not sure
Never heard of it.

I voted yes with the caveat of paying close attention to the notes at the bottom.

Absolutely! I am in London this week with IEC meetings and was able to talk at length with one of our committee members (in IEC language "a nominated expert") that was the main architect of the tests for this table. It was stated that there is a high confidence in the data provided the notes are addressed and some notes can be quite specific regarding exact type of equipment.

Only thing that makes me nervous is that for instance (and this is the one that has been a popular subject on this forum) the conclusions claiming 4 cal/cm2 for 250 VAC or lower are based on a vague reference. There are two entries in the table but for all practical purposes the result is the same and they can be combined to the same result: 4 cal/cm2 or less. It would be nice if the source for the information in tables 410-1 and 410-2 was a little better documented.

My concern is that it is unfortunate that I've seen a lot of completely unsupportable claims that somehow end up in a lot of standards. A lot of research on the utility side seems to understate the hazard while that on the industrial side seems to overstate it without any evidence whatsoever.

I voted yes, since calculating IE for every service is impracticable for a utility. Unfortunately, OSHA doesn't care too much for the values footnoted with 7 and 8.
Even though the interpretation is from 2015, I haven't yet seen anything yet from IEEE addressing their concern.

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=29693