Death by "toaster in the bath" - how much water before you survive?

This will seem like a really, really bizarre question, but I reckon there is a factual answer, so here goes.

This started, unsurprisingly, as a pub debate. The premise is this: if we take as fact that you can murder someone by throwing in a live toaster while they are in the bath, how big does the bath have to be before you survive? If you threw a live toaster into an Olympic-sized swimming pool, would the occupants die? How about the Dead Sea (or any large self-contained body of water)?

I suspect it’s a bit like the proverbial straw breaking the camel’s back, but one of the debaters was adamant that the size of the body of water was irrelevant. Enquiring minds need to know, and a beer may be riding on this!

To be killed by throwing a electrical device current has to flow through the body. And electrical current will take the path of less resistance.

Most of the current will pass from the point where the connection is made at the device. some current may travel from the hot lead through the water to the drain pipe if made of metal or depending on what the bath tub is made of and how the water pipes are run through the water to the tub and from the tub to the piping if connected to the tub.

If your body is in between the points where the current is flowing from to where it is flowing to some may flow through you.

Normally electricity kills by stopping the heart, I believe that is in the range of 1 ma through the heart, interrupting brain function, or in high current situations cooking part of the body.

Toaster lands in your lap you may be in trouble.
Toaster lands in water as you are touching grounded piping you may be in trouble.
Toaster lands in pool not near you, you probably will not notice.

It is all about the path the electricity takes.
The tossing the toaster in the water helps make good movies.

The first problem you have is that throwing a toaster into a bathtub in Hollywood somehow turns all of the water into this mysterious substance called “electrified Hollywood water” which is instantly fatal. That’s not how it works in the real world. So right from the start, your premise is flawed. You can’t reliably murder someone by tossing a toaster into the bathtub.

This doesn’t mean that it’s safe to throw a toaster into a bathtub, though.

Electricity flows in a circle if sorts, which is why we call it a circuit. It goes out through the hot wire, through whatever electrical load is present, and back through the return wire. In residential electric service, we use alternating current, which means that 60 times every second (50 in other parts of the world) the electricity stops and reverses direction, making a sine wave if you were to graph it. So half of the time, it goes out through the hot wire and back through the return wire, and half of the time it goes out through the return wire and back through the hot wire. So why do we have a “hot” and a “return” if they are both basically the same? That has to do with grounding, which has everything to do with your bathtub scenario.

You can run AC electrical systems that aren’t grounded. These are called isolated ground systems, or more commonly, just are called isolated systems. If you are unfortunate enough to be in the hospital, look for the red colored outlets. Those are isolated. Isolated systems are safer in that you can touch either wire and touch ground and not get shocked. So the next obvious question is, if it’s safer, why don’t we run all electrical systems that way? The answer is that if you try to run an entire residential electrical service that way, mother nature will randomly ground your system with tree branches and such. It is very difficult to maintain an isolated system, and we would much rather have a ground system that we make intentionally than a random ground system caused by mother nature.

So this is why your toaster is a shock hazard. One of the electrical wires (the return, aka the neutral) is physically connected to earth ground. Your water pipes, being metal and conductive (if you don’t have pvc) also go into the ground. So basically, all of your water and drain pipes are electrically connected to the neutral wire in your electrical service. Drop a toaster into the tub, and now there are two ground paths that the electricity can take. One is back through the toaster, the way it was intended to work, and the other is through the water, and down through your water pipes into ground.

Because of the shock hazard, all modern homes are required to have ground fault interrupters (GFI or GFCI for ground fault circuit interrupter) in any “wet” locations, like bathrooms, kitchens, etc. You toss your handy-dandy toaster into the tub, the GFCI detects that the current going out through the wire doesn’t match the current coming back in, and the outlet pops off, leaving your intended murder victim to glare at you rather angrily and forcing you to use something a bit more reliable, like holding their head under the water to drown them.

But, for the sake of argument, let’s assume that this is an older house, built before the days when GFCI outlets were required in the bathrooms. Now you toss your toaster into the water, and part of the current goes back through the toaster and through the wire, and part of it goes through the water, and through your victim, and down through the water pipes to ground. At this point the natural tendency is either to jump up out of the water or to grab the toaster and throw it out of the tub. The latter choice is very, very bad for you, as this results in part of the current going through the toaster, and part of it going down your arm, through your chest (that’s the really bad part), through the rest of your body, into the water, and down the pipes, etc.

But here’s the thing. Relatively low level shocks like this are not guaranteed to kill. The risk here is that the electricity will interfere with your heartbeat, and this is a bit hit-or-miss. The shock has a decent chance of throwing your heart into fibrillation. Your heart has a funny design in which this fibrillation state is stable, meaning that the heart will stay in fibrillation quite happily until something else forces it out of this state (like a portable defibrillator). While it is in fibrillation, your heart isn’t pumping blood. It’s kinda just shaking chaotically. You pass out in a matter of seconds, and if no one does anything, you die in a few minutes from the lack of blood and oxygen to the brain.

Fibrillation isn’t guaranteed, though.

And, if your victim jumps out of the water instead of grabbing the toaster, more current flows through the water than through them, and the chances of fibrillation occurring are much, much lower.

So a bathtub alone is actually quite survivable.

On the other hand, under two identical sets of circumstances, one person might go into fibrillation and the other might not (there’s a lot of luck involved and the heart is more susceptible to disruptions at certain parts of its cycle than others, so exactly where the heart happens to be when the shock is applied also matters). So this is definitely not a safe thing to do, and there’s a really good reason that we invented GFCIs and have made them mandatory in bathrooms.

I’ve never tried it myself, but I’ve heard from people who have had electrical faults in flooded basements and swimming pools. They describe feeling a tingling as they waded through the water, starting at about maybe four to six feet away from the fault. Note that if you can feel the tingling, there’s more than enough current there to cause fibrillation, so this is definitely one of those “don’t try this at home” types of things. The tingling gets more intense as you get closer to the electrical fault. Again, it’s not a safe thing to do, but in Hollywood there would be sparks everywhere and everyone who was even partially touching th water from any distance would die very dramatically.

You can wade through a basement or a pool with an electrical fault, and probably won’t be killed. A bathtub is kinda iffy. Chances are you wouldn’t be killed, but I certainly wouldn’t want to risk it myself.

Nice discussion. I think there should be some kind of general rule out there stating something like:

“Almost anything anyone does in a movie intending to kill his victim is unreliable and probably wouldn’t work in real life. Conversely, most things movie characters do to temporarily incapacitate or disable someone is likely to kill or permanently maim them.”

I don’t really think the “amount of water” is the question. It’s more that electric current is being introduced into the water, and it will take the path of least resistance to the nearest ground, at least some of it will, some will go back through the return wire on the appliance.

In older construction, the metal piping will be a path of least resistance, but in a small enclosed pool of water (like a tub) there’s certainly a chance that the current will travel through a body in the tub, and through the heart, and subsequently cause death. But that’ll depend on a lot of factors and may not happen. There’s actually a good chance in older construction, it won’t blow a fuse or trip a circuit breaker, either–which is ultimately how people used to actually die like this. There are stories (more from longer ago) of tragedies where people were electrocuted when a running hair dryer was dropped accidentally into a bath tub and etc.

Modern construction the pipes often won’t be a path of least resistance, but additionally, I think in most places it’s now been standard for 25+ years that bathroom outlets have to be GFCI outlets (the outlets with the little red and black buttons on them), these trip when they detect electricity from a device is going along an unintended path–and in so doing save lives, because they do so essentially immediately. That means from a practical standpoint this “shouldn’t happen much” in modern construction. If you want to get stupid there’s always opportunities though, there’s no reason you couldn’t run an extension cord from a non-GFCI outlet to introduce this scenario into a modern bath tub.

In a big pool of water the same principles all apply, if the path of least resistance goes through your body, and particularly goes through your heart, the electricity can kill you. This is true whether it’s the community swimming pool or the Atlantic ocean. If a you’re swimming in the ocean and a bolt of lightning strikes it so close that the current passes through you, it doesn’t matter that the ocean is huge, you’re still likely to suffer serious harm. If it strikes 100 yards away, it’s highly unlikely your body is going to be a path of least resistance for the current, same for a plugged in toaster thrown into the other side of the swimming pool. If someone throws the plugged in toasted and it hits you square in the mid-section as it submerges in water, there’s a much higher chance that your body will be along the path of least resistance. The volume of water doesn’t matter so much as the path the electricity is going to travel, which is independent of how much water there is. The reason a bath tub is more dangerous is that since it’s a much smaller space, your body fills up a large portion of it, a plugged in appliance “randomly dropped in” is much more likely to create a scenario in which your body is along the path of least resistance than a large body of water with a plugged in appliance “randomly dropped in.” If the appliance is aimed directly at you in both scenarios then you’re in trouble if it’s not plugged into a GFCI outlet.

Consider (for me, if you will :))the 3-D envelope of possible least-resistance paths and the space in which, over a certain time, it travels – say from a current source loosed at the center of a copper-lined “aquasphere” filled with water.

(Visions of a Tesla sparky thingy…)

How’s the math for that problem set up?

So what are the odds for a given dimension within that sphere to be both “in” one of those paths? And then add to that the electrical features (which I don’t know what they may be) that an object of that dimension, relative to the copper boundaries, has as an alternative ground.

I presume it’s a statistical answer, but I’m equally interested in the parameters.

Who the heck keeps a toaster in the bathroom?
What are they doing – eating toast & marmalade while scrubbing their back?

I’ve always heard this about a table radio in the bathroom, which seems slightly more likely.

Didn’t this modus mortuandi make the big time in an early Bond movie?

Back in the days of tube radios, it probably made a lot more sense. There were no GFCIs and the voltage inside the radio was a lot higher.

And even if you did have a toaster in the bathroom, what are the chances you could drop it into the bath tub without unplugging it?

Water does not behave like a plasma, so unless the voltage and current are very, very high, you won’t usually get those breakdown paths as you describe.

Water will act as a dielectric and the volume in the sphere will have a potential field ranging from V at the source to 0 at the copper surface. From here, you need Gauss’s law and the volume of integration of a sphere to do the math, and I don’t want to do that cause it’s Sunday ;).

However, the upshot is that a current will flow through a path with a lower dielectric (say, a human body) depending on the potential difference between the inner and outer radius. So if you are in your proposed sphere, and swimming towards the central source, at the outside of the sphere, the potential difference between your hand and your feet is low, and minimal current will flow through you (oh yes, humans conduct electricity better than water). As you get closer to the source, the inner potential (your hand) rises faster than the outer potential (feet) (due to the inverse square law) and the current passing through you increases, until the critical threshold is reached and your heart gets disrupted. It gets worse if your feet are tethered to the outer shell by a conducting cable so they are always at 0 potential - the radius at which which you get a lethal shock could be quite a bit higher than if you were not earthed.

This is why you should crouch down and keep your feet together if you are caught out in a lightning storm - you need to reduce the potential differences between the various parts of your body - head to feet, foot to foot. When lightning strikes, the potential wave in the air and ground can induce currents between different points, and the closer they are together, the smaller the current.

So wading through a flood and feeling a tingle means that parts of your body are in different potential fields. If one of those parts then accidentally gets earthed (touches a metal pipe, say) a lethal current may easily flow, even if I was 6 or so feet from the source of the fault - I’d be getting out at that point and leaving the issue to an expert.

I hope this is clear and makes sense.

Your comprehensive explanation brooks no argument from me apart from the above.

In the hospital where I worked the significance of the red outlets was that they were the ones that were connected to the emergency generator. Anything connected with life support was plugged into one of those. Ordinary equipment like sterilisers or floor cleaners were not.

Can I just:

  1. High five everyone who has replied
  2. State that I fucking love this message board

You have simultaneously answered the question, and provided enough material to keep the pub conversation going for months. Superb.

oddjob was killed reaching for his steel brimmed hat embedded in a hot wire IIRc

I’ve never had to do electrical work in a hospital, so am that familiar with the codes there. It is my understanding is every outlet in a hospital is on an isolated ground.

I think Mythbusters confirmed that you can kill someone this way, which I know because a good friend of my fathers killed his wife this way.

Paul Bartel proved a bug zapper could do the job

IIRC, most building codes in the US specify that all electrical outlets within six feet of a bathtub or within three feet of a sink must be GFCI. Doesn’t that greatly reduce the risk of electrocution? Otherwise, why bother putting it in the code?

A hair dryer might be most plausible today.

In the UK, you are not allowed to put anything other than a shaver socket in this area. Of course, that doesn’t stop people from running an extension lead in there.