THIS JOB IS DANGEROUS. We place ourselves in situations with uncertain outcomes. In the heat of the moment, with an imminent rescue on the line, our personal safety often takes a back seat to the perils of the environment.
We are conditioned to trust our gear under some of the most severe thermal hazards imaginable and we move forward. The research and development inherent in today’s modern structural firefighting ensemble are tremendous, representing more than 50 years of incremental adjustments intended to keep our crews from being burned, contaminated, or otherwise injured at an emergency scene. This hand-wringing evolutionary process is reflected in our emergency personal protective equipment (PPE) standards. And from a thermal protective viewpoint, these improvements are working. They have worked so well that most of the time we assume that we will be fine—certainly from a thermal perspective.
However, thermal hazards are not the only perils that our fire crews encounter on a regular basis. Shock energy hazards are real and always present. You should consider them high frequency and high hazard, as they are almost always a part of an emergency scene. And they represent a potentially lethal encounter. All responders must anticipate and prepare for these hazards. We are grateful that our predecessors recognized the need for shock protection for our profession.
Now, let’s be clear on this: There are no electrical shock protective expectations for your structural firefighting coat and pants. The only validated and tested portions of gear reside with your National Fire Protection Association (NFPA) 1970, Standard on Protective Ensembles for Structural and Proximity Firefighting, Work Apparel, Open-Circuit Self- Contained Breathing Apparatus (SCBA) for Emergency Services, and Personal Alert Safety Systems (PASS), compliant helmet and boots.
When you first put on that new set of bunker gear, it often feels a little stiff, albeit fresh and forgiving. Breaking it in can take a few shifts. From a protection standpoint, you likely presume it to offer peak performance. Over time, you’ll expect it to fray, stain, and tarnish a bit. But the thermal protection is still largely intact, despite the natural fatigue of the gear.
When it comes to reductions of the shock protections in our boots and helmets, the results can be calamitous. In an instant, you can go from protected to injured. And this begs the questions, How do the conductivity protective features perform as the gear ages? Are there clear visual indicators that those boots and helmet have lost their ability to protect us from electrical shock environments, common to every emergency scene? These questions linger, with no clear answers.
I (Chris Greene) have personally performed hundreds of bunker gear inspections, but I had never considered how to evaluate gear for shock protection. I simply assumed it was in place and functioning as designed. This was a mistake, and one that many make.
This oversight represents yet another gap in energy hazard training for the fire service. As you read through this article, it is important to have some perspective about its applicability. Despite the performance standards that exist to provide protection from high-energy conductors, deviating from your department’s policies, NFPA 70e, and good judgment when you’re operating near live electrical lines is a really bad idea.
This article does not intend to encourage complacency or comfort in and around energy hazards. These electrical-resistance portions of the standards represent a very passive safety net. Don’t push your luck with electrical energy.
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- Changes Challenging PPE Choices and Care
- Frequently Asked Questions on Restricted Substances in Protective Clothing
- How Do I Comply with NFPA 1851? Five Options
Data Interpretation
I’ll be honest, when we began discussing the implementation of this research project, I had some biases about what I believed would happen. I believed boots that had been in service for longer than six months would fail the conductivity test. And I mean fail badly. As for the helmets, I figured they would maintain all their shock-protective features if for no reason beyond the fact that the threshold is only 2,200 V as compared to the boots, which are 14 kV.
I sure figured wrong. Although we had a small data pool, what we found was that the boots were more likely to retain their shock protective features, per the testing standards, over time. This research indicated only 9% of the boots failed. However, the helmet failure rate was much more drastic: 40% of the helmets failed the standard test for electrical resistance. I did not see this coming.
Potential Standard Gap
The electrical hazard testing standards in place for firefighter boots do not reflect the actual working conditions for the profession.
The professional firefighter operates in an environment that is considered “at risk” for electrical shock injuries. Employees who are at risk for electrical shock because of their work environment are expected to wear foot protection that meets ASTM F2412 and ASTM F2413 standards to ensure the footwear’s protective features meet or exceed the hazards of the workplace.
Boot Wet Test Results
Only two boots were tested due to financial constraints.
- Test 1: Fail caused by breakdown at 8 kV with 8 mA of current.
- Test 2: Fail caused by breakdown at below 8 kV with 3 mA of current.
Conductivity Fatigue Research Project
In November 2024, the international Association of Fire Fighters (IAFF) and UL Solutions conducted a research project intended to better understand how the shock protective features of firefighter boots and helmets may diminish over time and use. The standards referenced for defining and validating these protective features are American Society for Testing and Materials (ASTM) F2412, ASTM F2413, and NFPA 1970. This research was conducted at UL Solutions, at Research Triangle Park, in North Carolina.
| BOOTS (photos 1 to 5) | HELMETS (photos 6 to 8) | |
|---|---|---|
| Scope of work for electrical conductivity testing (Figure 1) | Testing was consistent with ASTM F2412, ASTM F2413, and NFPA 1970. | Testing was consistent with NFPA 1970 9.6.1 Electrical Insulation Test 1, Procedures A and B. (Helmets are required to pass a two-part test.) |
| Number of testing subjects | 22 (from multiple manufacturers) | 15 |
| Materials | Leather and rubber | Composite material from multiple manufacturers. (Leather helmets were not available for testing.) |
| Voltage tolerance | 14 kV for 60 seconds | Procedure A: 2,200 V for 60 seconds Procedure B: 2,200 V for 15 seconds at all metal parts on the helmet’s exterior and above the brim edge |
| Conditioning (Boots and helmets must be placed in a room or space for a predetermined amount of time with specific temperatures and humidity levels.) Shall be conditioned at a temperature of 21°C +/- 3°C and relative humidity of 25% to 50% for at least four hours. Specimens shall be tested within 5 minutes of removal from the conditioning room/space. | Shall be conditioned at a temperature of 21°C +/- 3°C and relative humidity of 25% to 50% for at least four hours. Specimens shall be tested with 5 minutes of removal from the conditioning room/space. | Shall be conditioned at a temperature of 21°C +/- 3°C and a relative humidity of 65% +/- 5% for 24 hours and shall be tested within five minutes of removal from the conditioning room/space. See ASTM D1776/D1776M, Standard Practice for Conditioning and Testing Textiles. |
| Results | Passed: 20 boots Failed: 2 boots | Passed: 9 helmets Failed: 6 helmets |
| Reasons for failures | Each appeared to be the result of a metal intrusion, likely a nail, in the sole of the boot. Neither of the boot failures was the result of current leakage at the prescribed test voltage of 14 kV. Both failures were due to breakdown/arcing (photos 1 to 5). Breakdown occurred when voltage reading was between 9 kV and 10 kV. | Procedure A: Partial submersion water test with 2,200 V application2 failures caused by breakdown Locations: Near the most forward “Eagle Mounting” area. Procedure B: Metal head form test with 2,200 V applied to any metal located above the helmet brim line. 4 failures due to current leakage at multiple locations. |
