Is 277V actually more dangerous than 480V or is it just old school myths?

The idea that 277v is more dangerous than 480v becuase of the "let-go" threshold vs the "blast" effect is one of those half-truths that gets oversimplified in the field. Scientifically, 277v is right in that sweet spot where the voltage is high enough to penetrate skin resistance easily but often isn't high enough to cause the massive, violent muscle contraction that might physically throw you clear of the circuit. It results in a **tetanic contraction**, where your muscles lock onto the source, and you’re basially cooked from the inside out til someone kicks the ladder or the breaker trips.

I've seen guys get hung up on 277v while working on lighting circuits. One guy I worked with years ago got stuck on a ballast wire while on a lift. He couldn't scream, just made this weird grunting sound. He only got off because he fell and his weight tore him loose. His skin looked like it had been through a shredder. With 480v, you’re usally looking at a phase-to-phase fault. The energy release is so much higher that the resulting arc blast or the sheer force of the muscle spasm often physically separates you from the conductor. It's not "safer," it just fails differently.

The reason people talk about 277v being the "killer" voltage is mostly about exposure. Most electricians treat 480v gear with a lot of respect—they're wearing the suit or at least powering down. But 277v is everywhere in commercial lighting, and people get lazy. They work it live because "it’s just a light circuit." That complacency is what kills you.

In reality, the path through your body and the duration of the contact matter more than the specific voltage. If you’re sweaty and you’ve got a solid grip on a grounded conduit with one hand and touch a 277v lead with the other, your heart is right in the line of fire. Don't buy into the myth that one is better to get hit by than the other. Both will stop your heart if the conditions are right.

I’ve seen plenty of guys swap out ballasts while the power is still on, and it always sketched me out. If 277v is that 'sweet spot' for locking up, does the frequency of the power have anything to do with it, or is it purely the pressure of the voltage? Also, woud standard EH-rated boots even do anything at that level if you accidentally touched a grounded grid while working?

EH boots only work if you're not grounded elsewhere. When you're up in a T-bar ceiling, your shoulder or back is usally touching a grounded duct or the grid. In that case, those boots are useless because the current finds a shorter path thru your torso instead of going to the floor. People also forget about the breaker. A standard 20-amp lighting circuit won't trip while you're getting cooked. It doesn't see your body as a fault; it just sees a tiny load. You’ll be long dead before that OCPD reacts. That’s why the "hang up" is so lethal—there’s nothing to stop the flow til someone else hits the switch.