How much spandex is allowed in arc rated clothing? I noticed that some arc rated clothing will have 2% or even 7% spandex. How much is too much? Is there a limit on the amount of meltable material that can be in arc rated clothing?

130.7(C)(14) was added to NFPA70E in 2018.

This is wording from the Forward to the 2018 edition
"Section 130.7(C)(14)(b) was added to provide guidance on conformity assessment of PPE. These changes
do not alter the employer’s responsibility for determining the validity of the PPE manufacturer’s claims."

Melting fibers are in most AR garments. Flame testing and arc ratings make the call. In 1994 there were NO melting fibers in most fabrics but performance standards keep out the bad things but allow fabrics to have better performance without specifying too tightly. This is happening in more PPE but fabrics have benefited the most. I have seen as many fabrics with much more spandex pass. It's pretty easy to use up to 15% nylon, polyester or spandex/lycra with no measurable effect. After that companies have to do something unique. The arc rating with full ASTM F1506 testing is the key to compliance.

Happy to help if companies have concerns. We provide a "garment audit" at ArcWear to check for products with problems.

Hugh Hoagland