This test method is intended for determining the heat attenuation factor (HAF) of a shield material and the effective heat attenuation factor (EHAF) at the location of the worker in a specific test set up.
These shields are used by some utilities for switching padmount gear when it may have an arc flash potential. They fit on a racking screw to shunt energy away from workers racking breakers.
We saw one accident in southern California where the padmount arc flashed and caught the truck tires on fire. The zone the worker was standing in received almost NO energy. The shields are poly-carbonate and allow full vision but block 50% of the energy in a butted electrode arc and shunt away much more in an ejected arc.
This is an excellent engineering control listed in NFPA 70E and OSHA 1910.269 as preferable to ONLY using PPE. We never recommend using AR garments when using the shields, but they can be part of a risk control in many settings.