Shock - 120V vs 480V Electrocution

Timeismoney08 · Apr 23, 2019

Hello,

I've always heard that 120V is more dangerous because it is more likely to hold you in place and also will have more current run through you than 480V. Of course most people will not contact both legs, so it's really 277 vs 120.

I like to think Power is what kills you, not just Amps. Is this correct?

I've always wondered about the statistics of electrocution. Is it just that more people are exposed to 120 or is it really the more dangerous of the two?

scott.lawrence · Apr 23, 2019

120VAC is more dangerous b/c it's more common, especially for DIYers

amps are what kills

mylespetro · Apr 23, 2019

My understanding (which may be very wrong) was that voltage and current are harmful in different ways. I think that voltage can send your heart out of rhythm, while current literally burns its way through your body. I believe voltage also causes tetanus (muscle contraction, not the infection), which is why it causes people to be unable to let go of the conductor.

I'm sure my understanding is flawed in some way, so please don't take this as professional advice in how to approach live conductors.

EDIT: Just a note, electrocution is defined as death by electric shock, literally a portmanteau of electric and execution.

Maxkling · Apr 23, 2019

scott.lawrence said:
120VAC is more dangerous b/c it's more common, especially for DIYers

amps are what kills

A static discharge can have up to 10-15 amps at 25k volts. It’s the amount of energy over time that is the killing factor.

I’ve always heard 120V is more common which is why it’s dangerous.

geniusintraining · Apr 23, 2019

Speaking from experience

The worst one I had was 120, I was working on a jogging table and the table controls were activated by two aluminium handles that would engage the jog or tilt of the table, I was told it was not working so.... kneeling down on both knees and holding on to the table controls I started moving them back and forth one of the micro switches was shorted and proceeded to give me 120 through one arm and out the other, but the bad part I could not let go, lucky one of the other guys were walking by and unplugged it, it was only about 30 sec but it was the longest 30 sec of my life, at the time I was into building my body and working out, I had 19 inch arms so I was not a wimp but it was impossible to let go

I have been hit with 277 lighting and 480 but being shocked and popped by voltage/current are different beast

Either way its something that we all should avoid

Bit_Bucket_07 · Apr 23, 2019

Timeismoney08 said:
Hello,

I've always heard that 120V is more dangerous because it is more likely to hold you in place and also will have more current run through you than 480V. Of course most people will not contact both legs, so it's really 277 vs 120.

I like to think Power is what kills you, not just Amps. Is this correct?

I've always wondered about the statistics of electrocution. Is it just that more people are exposed to 120 or is it really the more dangerous of the two?

More people are injured by 120 VAC circuits merely because there is more exposure to them. It is irrational to attempt to separate voltage from current when discussing electricity, since amperage is a function of applied voltage and impedance. You can't apply voltage to a conductor (including a human body) without inducing current flow, and you can't have current flowing in a conductor without an applied voltage.

Therefore, your assertion that "power is what kills you" is accurate, while the concept of a lower voltage creating greater current flow is inaccurate. Getting "stuck" to an energized circuit is a function of loss of muscle control after having grasped an energized object. It's not as if the electricity somehow magnetizes your body.

Aabeck · Apr 23, 2019

I used to work at a machinery builder the boss had his own way to check for blown fuses.

He said that since the electricity will pull a finger down that if you touched the live terminal with the back of a finger, and it was live from a good fuse, the finger would actually pull away from the fuse.

I saw him do this many times on 240 & 480 - I think he was too cheap to buy a meter.

Myself, I always have at least one meter that works.

LadderLogic · Apr 23, 2019

Aabeck said:
He said that since the electricity will pull a finger down that if you touched the live terminal with the back of a finger, and it was live from a good fuse, the finger would actually pull away from the fuse.

Actually, this is the proper final step in making sure the power is off after checking it with a meter - to touch the conductor with the OUTSIDE of your palm. if it somehow is still hot, the muscular spasm will cause your hand to move away rather than to grab it.

Toine · Apr 23, 2019

That is one I am not going to try if there is no need, but thanks for bringing it up and explaining. I took a mental note since this can be a life saver.

Aabeck · Apr 23, 2019

LadderLogic said:
...after checking it with a meter...

That sounds reasonable - but this guy did it in live panels.

I was in a header shop where an operator got stuck to a coil steel feeder by holding the grounded steel and the (live) jog pushbutton. All he could do was scream until another operator ran at him and tackled him off the machine.

It didn't look like fun. And, in 35 years now, I have never been shocked except for being tingled when rewiring household things with the power on.

Ken Roach · Apr 23, 2019

My electrical inspector has three intact fingers, and a sleeve full of skin grafts, from an arc explosion that was not his fault. We take his advice very, very seriously.

I just have a numb fingertip and a tiny scar to remind me what 277 volts to ground across your heart feels like.

I carry a Klein NCVT all the time, even when out walking the dogs (there was a spate of energized utility vault covers in the city).

alive15 · Apr 23, 2019

If anyone is having second doubts about there work, please contact me for new job opportunities. Haha jk

T Gibbs · Apr 23, 2019

It's just basic ohms law. Your body has X ohms of resistance. 120v will push Y amps through X ohms. 480v will push 4Y amps through X ohms.
The worst I ever got was 600+ VDC from a VFD brake resistor. It felt like somebody hit me with a sledgehammer.

lfe · Apr 23, 2019

It depends on many factors, the sensitivity of each one, which way the current flows through your body etc.,

Many years ago I rescued a worked who was immobilized with an old AC welding transformer that theoretically only gave 60-70V , he stayed with one hand gripping a metal structure and the other holding the clamp that had lost parts of its isolation.

mendonsy · Apr 23, 2019

An electric fence charger will get your attention also. Not much current output, but typically at 8 - 10 Kv.

Shock - 120V vs 480V Electrocution

Timeismoney08

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scott.lawrence

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mylespetro

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Maxkling

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geniusintraining

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Bit_Bucket_07

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Aabeck

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LadderLogic

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Toine

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Aabeck

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Ken Roach

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