Arc-Flash Testing Debunks Pressure-Wave Myth, Points to Thermal Burns as Real Risk
Arc-rated PPE isn’t optional just because “the blast will kill you anyway,” Safety+Health Magazine reports, citing new arc flash testing from Tyndale Co. that challenges a widespread myth among electrical crews. In tests conducted at incident energies from 3.7 to 29.2 cal/cm² at an independent lab, clothed manikins weighing around 42 pounds were never knocked over or thrown back by the pressure wave, even at the highest energy levels. Tyndale also reviewed security camera footage of real arc incidents and found no significant blast injuries in any case. Master electrician and arc flash survivor Jason Brozen confirmed the pattern from his own experience: his life-threatening injuries came from thermal energy that burned exposed skin and ignited his non-flame-resistant clothing, not from being thrown by a blast. Separate testing showed that flammable clothing can ignite even at 120/208V and low incident energies, causing catastrophic burns within seconds, while workers wearing properly matched arc-rated PPE avoided ignition and burn injury entirely.
What It Means for Subcontractors
- Electrical and E&I crews working live panels should treat “de-rating” incident-energy exposure as a documentation risk, not a shortcut: Tyndale’s data shows thermal burns and clothing ignition, not blast force, drive nearly all serious injuries, so PPE selection must match the calculated incident energy, not an assumption about survivability.
- Safety managers should confirm workers are not substituting non-FR base layers or work clothes under arc-rated gear, since testing found ignition occurred at low incident energies and even at common 120/208V circuits.
- Crews should prioritize full de-energization procedures before relying on PPE as the primary control, and document arc-flash hazard assessments and PPE category assignments per job to support compliance if incident energy is later questioned.
