I know you need to wear an Arc Rated face shield if you are exposed to 9 cal/cm2 or higher single phase-to-ground exposure on the utility side per the new OSHA standard. I have also found where it states that a need for an Arc-rated shield [is necessary] if the cal/cm² rating is greater than 5 cal/cm² on three-phase exposure. I understand that the three-phase calculation is different than the single-phase-to-ground [calculation]. Can you clarify for me how I should correlate this into our work practice? Right now there are only a few circuits we might work on that are high calorie circuits, and we are informed of that prior to our arrival so we can have the proper PPE required.
The OSHA 1910.269 standard is trying to make it practical that most single phase arc situations (overhead power lines) will not require a face shield. Most other arc hazards (enclosures and any 3Ph arc) will require face shields.
The goal of OSHA, as I have understood it, was trying to be practical for overhead work and to take into consideration several things about overhead work.
The hazard assessment is the responsibility of the company, so you CAN wear shields at a lower level but are not required to by OSHA.