Why does an electric shock feel like that?

No tricks, just working with your basic household electric stuff–maybe swapping out an outlet or a lightswitch. Or messing with those monster-sized christmas lights back in the day. So yeah, you’re doing stuff with household electricity and you get ‘bit.’ It’s kind of an unpleasant pulsating sensation.

Why is that? Is the electricity pulsing slowly enough to feel it, or is it more of a muscular response to the juice?
Bonus question: When we were kids wandering the wilds of horse country, we’d sometimes come upon a live electric fence. It was great fun to grab your buddy’s arm with one hand and then grab the electric fence with the other because you wouldn’t get shocked–either not at all or not terribly, I can’t recall now but the shock was certainly no deterrent–but the downstream guy got the worst of it. Why was the shock worse for the downstream guy, and why didn’t the prankster’s heart ever stop?

To answer the first question: In an AC circuit such as those in your wall, the electricity actually sloshes back & forth at 60 cycles per second (or possibly 50 cycles per second depending on where you live.) When you complete the circuit with your finger, this causes a flow of electricity through your muscles, rapidly switching from one direction to the opposite direction every 1/60 of a second. This is what causes the characteristic buzzing sensation of AC. By contrast, batteries only drive current in one direction (rather than alternating the direction), and so a DC shock doesn’t give you the same buzzing sensation.

Your muscles contract when nerve channels in your body supply an electric shock. Getting current from any other source causes them to contract. Getting shocked with AC current causes them to contract and relax rapidly which heightens the unpleasantness.

I talked to electricians who have been shocked by AC and DC under various conditions and they say that DC is somewhat difficult to release from if you get your hand in it because the current causes a prolonged contraction of your muscles and makes your hand grip the contact point. AC current at least causes your muscles to shake and is a little easier to break away from.

As for your bonus question. The pranksters heart doesn’t sop because his skin, muscles and nerves form a better path through his body than does his heart. I’m not sure what upstream/downstream has to do with discomfort.

Sometime back - I did a safety training and electrical safety was covered as part of the training. The data does not bear out what you said - if looked at statistically.

There are 2 parameters that was talked about - 1> Threshold of perception for current (i.e. the minimum current that gives you the tingling sensation) and 2> Let-go current (current that lets you voluntarily withdraw)

I pulled out my notes and here are the numbers (there were lot of statistics involved since the data was i think normally distributed and depended on the person and the wires etc) :

1> Threshold of perception : For men, the mean value was 1.1 mA; for women, the mean was around 0.7 mA. Thresholds were lower when applied with gel electrodes like ECG.

2> Let-go current : For men, the mean let-go currents was 16 mA and 10.5 mA for women. The data had a wide variance though.

Here’s the most interesting part : The let-go current when plotted against frequency (log) produces a trough shaped curve. The let go current for DC starts out as high then drops as frequency increases but again rises with increasing frequency. There was statistical variability in this too - but the trend was consistent. Cite

Frequency for DC current?

DC = Dangerous Current?

0 hz

DC can be pulsed and so can not be constant.

Electric fence designs vary. Most of them use high voltage pulses (either AC or DC, depending on the system). The pulsing is intentional so that your muscles won’t clamp and you’ll easily let go. They also have current limiting which keeps the current flow below the level where it could potentially stop your heart.

There have been people who have just taken the hot wire from a 120 volt circuit and have run that around as their electric fence (which is an incredibly stupid and dangerous thing to do). As you’d expect, touching one of these fences can be lethal, for both humans and animals.

The shock isn’t always worse for the downstream guy. A lot depends on how conductive the path is from your feet down to the ground. On wet soil with fairly conductive shoes the shock will be worst for the guy touching the fence and will diminish as it goes down the line, since the current flow will be split at each person between the ground through their feet and the next person down the line.

Direct Current.
House voltage is AC, Alternating Current. There was a big argument over which to use for distribution between Thomas Edison and Westinghouse.

Speak for yourself :stuck_out_tongue:

I strongly suspect that humans have not evolved any instinctive defense to HV, (High Voltage whether AC or DC).

Many forces, high acceleration, changes in atmospheric pressure, ambient light levels/flicker/colour temperature, radiation, noise are recent phenomena.

Sadly,the description of external forces alone, doesn’t give the ‘wise ape’ the ability to cope without preparation.


I was zapped by 230v when I was 14 years old. I remember a sudden vibration feeling through my whole body. It wasn’t very painful, just frightening and confusing. I couldn’t stop shaking for 30 minutes or so.

BOTH. 50 or 60 Hz is not so fast that the neurons won’t confuse it for pain.

As for the electric fence, the prankster knew it was going to happen, so didn’t feel it so bad… all other things being equal. Also the prankster may be conducting the current through to the target’s sensitive area, the rib cage or face or something.

The electric fence is designed on the principle “volts jolt, amps kill”… with very limitted current the heart chemistry is not upset.

The guys I know that have been hit by high voltage DC say it’s a lot like being hit with a sledge hammer. I solid hit that will knock you on your ass and hurt for weeks.

I’ve been cautious enough to never get hit with any heavy current. I’ve repaired plenty of damage caused by it and never want to get hit by anything that blows holes through solid metal.