PDA

View Full Version : Electric shock



lexxi
10-26-2018, 08:47 PM
Suppose an electrician character J wants to make it appear that another character P has tried to electrocute protagonist T.

J has rewired a light that T will need to touch in order to deliver an electric shock.

Can J calibrate the amount of electricity such that it will be more than a mild shock but not actually cause severe damage or death?

What would T experience when she gets shocked?

What might J do immediately to mitigate any damage and make it appear that he is being helpful (as opposed to responsible for causing it in the first place)?

MaeZe
10-27-2018, 02:58 AM
Why not just describe the actions and effects and not worry about actual numeric values?

frimble3
10-27-2018, 03:58 AM
A lot would depend on the intended victim - some people, in any accident, do better than others. Some people fall down stairs and get right up, some can break an ankle stepping off a curb.
Some people get zapped, say ouch and step back. Some people's hearts fail from the same zap.
So I wouldn't get hung up on exact numerical values, as MaeZe says, focus on the actions and effects.
Faulty wiring is so common that it would be hard (IMHO) to prove that it was deliberately done by anyone.

Also, to mitigate, pull victim away from the source of the shock (being careful not to get electrocuted himself), turn off power - at the electrical box if necessary. Then call 911 and help will come.

Al X.
10-27-2018, 04:54 AM
Here's the thing - a lot depends on your grounding conditions. Let's say you are wearing rubber tennis shoes and you accidentally grab a lead from a 110v electrical outlet. You will get a nasty shock, but the electricity has traveled through your hand. Stand in water? You're dead. It traveled through your heart.

I personally knew a guy, a Navy Seabee that was standing in a pool of water tending to an electrical box in a rain storm. He short circuited himself and literally his heart was ripped from his body. It was pretty nasty.

There is no way to 'modulate' AC power to receptacles and switches. You could rig up some sort of DC high voltage low power setup, but generally, shocks from the power distribution grid are either harmless or they will kill you.

WeaselFire
10-29-2018, 04:22 AM
It's not voltage, it's amperage. But electric shock can freeze a heartbeat and kill that way. Normal household current won't usually kill and normal bodily reactions break the connection pretty quickly. Touch something that seriously shocks and muscles contract, pulling away from the connection.

Things with capacitors are your secret here. Old CRTs for example, which can contain a lethal charge even when unplugged. Microwaves can be a source of serious danger in shocks. Older style camera flash systems.

It's really had to set up an "accidental" electrocution.

Jeff

starsknight
10-29-2018, 05:50 AM
Hi lexxi,

I saw some potential difficulties in the setup you described, but I'm not an electrical engineer. Fortunately, I know one, so I ran this scenario by him. Here's his response:


There are dozens of variables that make the proposed scenario difficult. One of the biggest is that depending on the individual's health and physiology, what would kill one person would not harm another; and you cannot possibly know enough about these things to guess correctly. And the obvious ones: skin resistance--can you control whether and how much the person is sweating? And with the starting point being 120 VAC household power, things like skin resistance would have a major impact. You mention how conductive shoes are, but most shoes would be sufficient to avoid any significant shock, let alone the surface upon which the person is standing (unless it is metal, or saturated with salt water), so you probably need to have them touch the two sides of the circuit with their two hands, doubling the effect of skin resistance variations. It is also not possible to predict the results of the muscular spasms that result from the initial shock--in your example the hand might clamp around the lamp but the arm might push the lamp over before that could happen, and so on.

My conclusion is that there are far too many variables to feel confident about the outcome. One could build a high voltage circuit with precise current limiting, but even then you have the health and physiological considerations mentioned previously.

I wouldn't touch it with a 10-foot Fiberglas® pole.

It's possible to set up a shock which will generally be incapacitating but nonlethal (think Tasers), and the way that's done is by using high voltage with low current. But something like that would always be nonlethal (barring unusual preexisting health conditions), so it's not going to look like an attempt to kill the character.

One possible way I can see for you to write around this would be to have J create an actual potential deadly trap in T's house, making sure to leave some very subtle type of evidence that he'll be able to "spot" and point out to her before she touches the light. This only works if he's present with her at the time, but based on what you asked about him taking immediate action, I'm assuming he's there with her.

For that matter, that could be J's dastardly plan, but perhaps for some reason T ignores what he says and touches the light anyway, gets lucky, and lives, giving J a pretty big scare in the process.

Of course, the above would require J either being overconfident he can stop T in time or willing to risk her life if his plan goes bad--and I don't know if either of those possibilities is in keeping with your character. Lots of stuff to think about/potential variations to play with.

I hope that's helpful!

(Sidenote: I recently read a novel that mentioned a weapon which discharged "thousands of volts of current." I don't think laughter was the result the author was going for. ;) If you discuss electricity in your book, make sure you know the difference between voltage and current.)

lexxi
10-30-2018, 08:17 AM
Thanks, all!

BTW, this wouldn't be happening in a home, but backstage at a theatre. So there could be some higher voltage(?) instruments or power sources, or more typical domestic ones, whichever works better.

Maybe it just needs to look like P was trying to scare T, since that's all J is really trying to do -- as well as framing P.

starsknight
10-30-2018, 09:31 AM
Hi lexxi,

Having worked in a number of theatres, I can tell you that everything I worked with was standard power/outlet arrangements (120 VAC, assuming US). Also, backstage could get really tricky in that there'll be a lot of people potentially back there: definitely the stage manager, cast, and crew, quite possibly the director at various points, in many productions an assistant stage manager, assistant director, dressers; wig, costume, and make-up people, etc. That's a lot of people to potentially get electrocuted, so I assume J has a way to make sure T is targeted rather than anyone else? Something to think about . . .

WeaselFire
10-30-2018, 04:59 PM
Never encountered anything higher than 220v at 200 amps in a US theater, very similar to household current. And, as mentioned, way too big a target pool to have it happen at random.

You can solve the latter problem by rigging the dressing room where no one else might be. The former would depend on a preexisting condition for your victim, maybe a heart issue only the killer knows about. Or give him a pacemaker and rig the microwave.

Jeff