Shock, Arc Flash, and Arc Blast

Shock happens when you become part of the circuit and current flows through you — usually hand to hand or hand to foot, straight across the chest and heart. The results range from a jolt to cardiac arrest depending on how much current flows and how long it lasts.

The defenses against shock are the ones you already know: de-energize and lock out before you work, keep grounding intact, use GFCI protection on temporary power, and keep insulation — gloves, mats, tools — between you and any live part you can't kill.

An arc flash is a fault where current jumps through the air between conductors. It releases a burst of heat and light that can reach roughly 35,000°F at the arc — several times hotter than the surface of the sun. It happens in a fraction of a second.

Arc flash burns skin, ignites clothing, and damages eyes, and it can reach you without any direct contact. Common triggers are dropping a tool across bus bars, loose or corroded connections, and racking breakers in and out. This is why work near energized gear calls for arc-rated (AR) clothing and a face shield — regular cotton or synthetics can catch fire and make the burn worse.

The same fault that makes the flash also vaporizes copper and superheats the air, and that expansion creates a pressure wave — the arc blast. It can throw a worker across a room, rupture eardrums, and turn tools and molten metal into shrapnel.

You can't 'PPE' your way fully out of an arc blast — the real control is not being in front of the equipment when it's energized. That's the point of approach boundaries and of de-energizing whenever you can: distance and dead equipment beat any amount of gear. When energized work truly can't be avoided, it takes trained, qualified workers with the right rated PPE and a plan, not someone reaching in to 'just check something.'