Do I need to wear a face shield, hearing protections, clothing that doesn't melt, and heavy duty leather gloves when replacing a AA battery on my Sony Walkman? Serious question. Based upon my reading of the NFPA, it appears the answer would be, "Yes", because that is the minimum standard for PPE.

According to the NFPA there is no CAT 0 or CAT -1. Anything with an incident energy of < 1.2 cal/cm2 is apparently lumped together without distinction. At which point does an incident energy rating become so low that wearing PPE starts to become absurd? I have been researching this topic for hours, including on this forum, and I cannot find any clear answers.

I work in a lab with 26V battery modules which according to our Arc Flash study have an incident energy of approximately 0.716 cal/cm2. They have delicate wiring harnesses with lots of tiny screws, but according to my reading of the NFPA we should be wearing heavy duty leather gloves, which makes it very difficult to perform the delicate work and lots of dropped screws. Some people in the lab don't wear gloves at all, some wear Nitrile gloves, and recently a manager said we should wear Class 0 rubber gloves, which are rated 1000VAC, which seems overkill.

Also, I read that while rubber gloves, without leather protectors, are permitted for delicate electrical work, they must be immediately discarded after use or set aside until they can be retested. Cheap Class 0 gloves on Amazon are around $45 each, which means disposing them after each use means the cost will rise quickly if we enforce this policy and we don't have a glove testing program at work, which is probably something that needs to be addressed.

I'm hoping that an expert on this forum can make sense of this craziness. What is the threshold for not wearing PPE? The answer has to be somewhere between "replacing a AA battery for a Sony Walkman" and the 26V batteries we use at work. Thanks for your help.

I can't make a legal interpretation or make recommendations but here are few things to consider:

50 Volts is where the requirements begin however there is quite a bit of language about being careful of hazards that still may exist.

The NFPA 70E Handbook explains 130.4(C) Equipment Operating at Less than 50V as: "under normal conditions, electrical conductors energized at a voltage less than 50 volts do not present an electrical shock hazard." "A thermal hazard can exist in circuits that have a significant capacity to deliver energy, even when the voltage level is less than 50 volts."

This could be from a large battery string for example.

Table 130.4(E)(a) Shock Protection Approach Boundaries "Not Specified" is listed for less than 50 volts.

Here is a letter of interpretation from OSHA regarding the subject:
OSHA Letter of Interpretation

Caution! Personal opinion ahead! From a career that has involved a lot with standards committee work, they have a difficult time excluding items directly unless it is 100% never a problem. i.e. 50V? don't worry about itIf someone is injured at less than 50 Volts (which has happened with large battery strings - small burn on finger) it could blow back. So the next best thing is imply it may not be a problem but surround it with enough language that it could be a hazard under the right circumstances.

Standards contain the best guidance that many experts and workers in a field have developed over many years of experience, but they can never perfectly describe and cover every possible situation you might face. With that in mind, here are some things that I write in every job plan and have signed off before doing any work like what you describe. Disclaimer: This is just me describing my process, it is neither complete nor advice nor a recommendation of any kind.

Hazard analysis part of plan:
List hazards that are or could be present when replacing the battery in the situation as described and the ways that will actually be used to eliminate each hazard. For each hazard that cannot be eliminated, develop a plan to reduce the risk to an acceptable level, the potential severity of injury to a minor level and the likelihood of an accident to extremely rare.

Specifically regarding any arc flash hazard:
Question: Can the NFPA 70E standard be used to determine if the standard applies to this situation and can it help with the hazard analysis, elimination or mitigation (Analyses, Labelling, Equipment, Procedure, PPE required, etc)?
Question: Even if NFPA 70E does not apply (unlikely if there is an arc flash hazard), can an arc flash still occur and if it does occur is there a possibility of causing injury?
Question: What qualifications and experience are required to perform these analyses and answer these questions?

Questions: Have all hazards been identified and mitigated in the written job plan? Following this job plan, Can this work be done safely? For example: I tend to be clumsy with tools and have poor balance. These are hazards I have to take extra precautions against causing injury to myself or people around me in every job plan. Sometimes that plan is to let other people do the work.

It seems to me that "delicate electrical work" would warrant creating an electrically safe work condition prior to being performed.

If you plotted out the incident energy you describe, presumably at 18" working distance, you'll see that it increases exponentially as you get closer to the point of exposure.