They are mentioned quite frequently. They are required anytime you have exposure to the head >1.2 cal/cm² or in all the PPE Categories. Arc flash hazards aren't technically voltage based. Any voltage greater than 300V or almost any typical three phase system has real potential of causing skin burn so the standard would usually require a balaclava. The early versions of NFPA 70E did not require a balaclava in the HRC level 0 and 1. But that has changed several years back. Most companies haven't updated to the newest versions.
I have performed several arc flash engineering studies in factories and facilities that are exclusively below 480V. Sometimes, no incident arc flash energies exceed 1.2cal/cm2 and in others, multiple instances exist.
There is a much stronger relationship between short circuit current and fault clearing time than there would using the system voltage only. Voltage tells us very little about whether we are definitely below or marginally above 1.2cal/cm2 (the onset of a second degree burn). An arc flash hazard analysis is required to make this call. More information is available at https://www.e-hazard.com/arc-flash-studies/
If after the study, all energies are less than 1.2cal/cm2, then you will NOT need a balaclava and would have documented evidence to present to OSHA. If, however, that is not the case, NFPA 70E - 2018 Table 130.5(G) clearly requires a balaclava. There are several other references that you can find by searching "balaclava" on our blog: https://www.e-hazard.com/blog/
To answer your question, look at Article 130.7(C)(10)(b)(1) in 70E-2018. It states "....an arc rated balaclava with an arc rated face shield shall be used when the back of the head is within the arc flash boundary." When using Table 130.5(G) for the selection of arc rated PPE read footnote b. It also states when the back of the head is within the AFB wear a balaclava.
Now for my opinion. For work at 480 volts and below I would say wear a balaclava when the AFB is 24 inches or greater. How I got to that number is as follows. The working distance to the torso at low voltage is 18 inches. After measuring my head and a couple of others I thought adding 6 inches to the 18 would define when a balaclava would be needed. Nothing prevents you from wearing one at a shorter distance.
Hope this helps.
Senior Partner e-Hazard Management
What I can't wrap my head around is on Table 130.(C)(15)(c), Arc-Flash PPE Category 1, you're not required to wear the balaclava. The incident energy is greater than 1.2 cal/cm² and it's inside the arc flash boundary.
Table 130.5(G), FN - Where the back of the head is inside the arc flash boundary, a balaclava or an arc flash hood shall be required for full head and neck protection.
130.7(C)(10)(b)(1) - An arc-rated hood or an arc-rated balaclava with an arc-rated face shield shall be used when the back of the head is within the arc flash boundary.
130.7(C)(2), ...All parts of the body inside the arc flash boundary shall be protected.
I find this to be a contradiction and I have not heard a clear understanding as to why this was done. Was it a mistake?
All the categories are stand alone. When you use the tables and meet the requirements for the fault current and clearing time, they are allowable. Otherwise you follow the other guidance you read. The items in CAT 1 are typical and a compromise for when a study is not available. CAT 1 AFB is 19 inches to the chest so the back of the head is NOT in the AFB. That is the assumption. Again, tables are a compromise and are typically OVER protective but not always.