Q: Now that the 2015 NFPA 70E has eliminated Category 0, I am confused on exactly what 70E requires workers to wear when the incident energy is below 1.2 calories.
Long sleeve natural fiber shirt and pants (cotton) seems like a good solution except cotton does not have an Arc Rating, so 70E says it’s not PPE .
Also, some literature suggests that we need a face shield in addition to safety glasses. (???) Any help you can give would be appreciated .
A: NFPA 70E now requires no PPE under 1.2 cal/cm² BUT the idea of natural fiber clothing is still in the standard and e-Hazard considers it a best practice for all three phase equipment.
When wearing AR PPE performing electrical tasks, melting garments are still prohibited even in under layers 130.7(C)(9) but may not be used if the breakopen level of the garment is exceeded 130.7(C)(9)(a). The prohibition of melting fibers “unless arc rated in a blend” is still in effect:
130.7 (C)(9)(c) “Underlayers. Meltable fibers such as acetate, nylon, polyester, polypropylene, and spandex shall not be permitted in fabric underlayers (underwear) next to the skin.”
When you have completed an arc flash study Table H.3(b) recommends in the informative annex to use non-melting (in accordance with ASTM F1506) or untreated natural fiber [though ASTM F1506 doesn’t really have any way to measure this we recommend confirming the materials are 100% natural fiber or expose to a 500F oven test]. We still recommend AR daily wear is best for electricians, and always wear safety glasses and a leather glove or an arc rated glove and turn the head away when operating any three phase electrical equipment if the incident energy is predicted to be less than 1.2 cal/cm2 and it is properly installed, maintained with no evidence of impending or historical failure.
Do a hazard assessment and a risk assessment. If equipment is poorly maintained or has any sign of impending failure or has a high incident energy which could ignite clothing, use good judgment by using AR PPE.
Remember, the company can require more than the minimum, and if you have calculations, the tables and the HRC/CAT/ARC levels do not apply. If there are exposed energized parts in the work workers are doing, AR gear is always required. So the idea of HRC 0 is alive and well in the standard but there is a little more freedom in not requiring it for operators of low voltage equipment <300V which poses and extremely low risk of arc flash. We recommend this use ONLY in single phase lighting systems like light switches and control switches <300V. Other exceptions may be built on the basis of your arc flash study, equipment design and maintenance level and risk assessment.
There are limited instances when <300V (208V 3P is an example) could pose an arc flash hazard when the fault current and clearing time are high, these should be assessed by a qualified engineer. IEEE 1584 should have better guidance by 2017.