query, electrocution in bath

[mick]

im puzzled and would like theory, dont want to do practical :)

if im in a metal bath ,which is earthed, full of water, and i drop an electrical appliance into the water (not onto me), would i be electrocuted, or would the electricitcy immeditely go to earth leaving me unscathed, as i would assume there would be no potential difference between me and the water . unless the electricity had to go through me to get to the water.

i know that if touched a live wire and it eathed through me i would be electrocuted due to potential diff,

alternatively if i stand on a 10,000 volt live wire which lies in a muddly puddle , would i be ok as surely the electricity would again flow to the earth mass and not through me,

promise im not planning on trying any on SWMBO.

honest

[ben]

Theory is ok, but there's nothing better than the practice. ;-)

[Andrew Gabriel]

The electricity goes through the water and you to get to the grounded bath. You probably conduct better than the water (being full of electrolites), so it will tend to concentrate slightly more through you.

'Stand' implies 2 feet on the ground. If there's a potential difference between them, current will pass through you. Cows are particularly prone to this because their feet are further apart (so there's like to be a higher potential difference between their feet than yours), the current goes through the chest area which is more likely to be fatal, they can't stand on one leg or otherwise stop the current flow, and they seem to be susceptable to much lower currents than we are. There are cases where an electricity pylon in a field has started leaking current to ground and killed all the cows in the field, but this is undetectable by humans and the cause of death is unlikely to be immediately obvious.

[Derek ^]

An appliance connected to 230v mains? Without any doubt at all.

An electric field would be set up in the bathwater between the live parts of the appliance and whatever is earthed in the bath (an earthed metal bath might still have an insulating vitreous enamel coating, the waste connection might be plastic). On the whole I think there would always be a good enough earth under all circumstances to permit a fatal current to flow.

Nope it doesn't take a simple straight line route to earth. It flows through all the bathwater, true the current density is in inverse proportion to the resistance (~ physical length) of the path but there'll always be enough to supply the 10 ma it takes to induce ventricular fibrillation.

No, same applies, and not just in the puddle, in the surrounding soil also.

In uni we did the calcs to show that you don't have to be struck by lightening to get electrocuted by it. Within say 10 metres of lightening striking the ground the electrical field strength during the strike could be as much as 1,500,000 volts per metre. Stand with your feet 1 metre apart and that's what you'll get.

Just remember, stand on *one foot* in thunderstorms.

On tiptoe.

DG

[Rusty]

I happened in one of the Bond films in the 60's so it must be true. Can't remember which one, but the guy who hurled the electric fire into the bath and dispatched the baddie was one S. Connery.

[Harry Bloomfield]

The current flow/voltage gradient would be dispersed throughout the the bath water dependant upon the resistance paths, with the lowest flow across the longest paths to ground. As the human body will likely have a lower resistance than the surrounding water, flow would be concentrated through it.

Most of the resistance when the body is dry, will be concentrated in the skin - which is why the used to wet the skin when placing a 'customer' in the electric chair. So when wet, much less voltage potential would be needed to kill.

[Colin Wilson]

I know of a horse that died in similar circumstances. Can't go into any more detail as there may be legal action still pending.

Oh, and the vet got a good jolt too when he put his hand in the horses' mouth :-}

Now you know why electric companies are not supposed to provide earths to farms with livestock - its the consumers' problem to make sure their earthing is up to scratch.

[Matt]

Oh how I wish you were a IMM clone!

[Derek ^]

To the people investigating who were all wearing green wellies?

But seriously, couldn't it be more likely the case that there was a single isolated flashover caused by a large bird colliding with an insulator?

DG

[Matt]

A flashover could case the same thing but you can quite easily get a resistive continuous fault (an insulator failing and the overhead line dropping and touching a stone wall or a tree) rather than directly touching the ground - that means the current can continuously flow through the ground as it closely resembles true load and not a fault. The voltage effectively drops from the voltage at the fault location to zero at the earth point. Small steps taken by a human can mean no shock, large steps (or space between points of contact) by a farm animal can mean a big shock and death.

[Ian Stirling]

If your house has a RCD, and the appliance is earthed, or the bath is earthed and has metalwork exposed to water, then the answer is that you can throw electrical appliances into it without worry. (more or less).

However, if you are relying on the fuse in the appliance, then it usually will not go immediately - bathwater isn't a very good conductor. A metal bath may actually make things worse. In most appliances, live and neutral are fairly close together. Considering a non-earthed bath, it may actually be not immediately lethal. Basically, you need a certain amount of voltage, as well as current to do damage. From some googling, I guesstimate that 30V AC across the chest is needed in order to get fibrilation. In order to get voltage across the chest, there has to be a voltage gradient in the water. This means that unless you're talking about a large heater (convector type, not fan) dropped in the water, the path from the live wires through the water to one side of the chest has to be significantly easier than to the other - and the same for neutral - otherwise there is no net voltage across the chest.

I'd go so far as to say that for a small device dropped in next to your feet, in a non-earthed bath, the risk of death due to immediate cardiac failure is near zero.

An earthed bath makes it much, much more dangerous.

[Derek ^]

I thought a fault was detected soon enough that a dropped cable was dead before it hit the ground.

Well a fallen conductor should be obvious to the green wellied ones.

Could also be that Bovine quadrupeds don't know, and get few clues as to "which way to turn" to minimise their electric shocks.

DG

[Andy Dingley]

Yes. Water doesn't conduct (worth a damn), but you do. For almost all reasonable configurations of you / bathtub / electric thing, then most of the current is going through you.

Bath salts however will change the conductivity of the water and may be enough to save you !

[The Natural Philosopher]

You all salty, conduct better than bathwater, especially if touching a tap ...

[Michael Mcneil]

I trust we shall all be enlightened when the legalities are concluded and/or you get out of gaol?

(Bookmarked this thread in case I miss it.)

Presumably when there is a change in the weather and almost every species of bird one commonly encounters in your region are sitting on bare wires carrying several volts more than is required to BBQ them, the preferred course of the electricity is a straight line?

I walked through the flood at Abergele several years ago. The tranformer

-right on the junction down which the sea poured every high tide; was still giving off quite a belt (Kinmel Bay -it's still there) where I was walking, until they were able to disconnect it several hours after the first high water.

I was wearing leather boots (and soaking wet clothing) and was getting tingling sensations, as was a fireman I was accompanying.

This was in knee to thigh deep water, dirty sea water. The tingling felt like I was walking through cress or some such succulent pond weed. Not at all unpleasant.

Perhaps the birds are having a foot-bath/massage?

[Michael Mcneil]

Isn't there some correlation with the place a coroner finds electrocution marks on the neck or shoulders of someone struck whilst standing under a tree and the height at which the trunk is dry for most of it's circumfrence?

[Colin Wilson]

I don't think i'm likely to hear the outcome of any legalities, but believe the problem was due to the consumers' installation - the owner of the horse felt differently of course, as they see anything to do with electricity being the electricity companies' fault.

[Andrew Gabriel]

Lightening does strange things. Victims usually have burn marks around all metallic objects, such as umbrellas, brief case handles, metal jewelry, metal buttons/studs in cloths. Oh, and you might want to check what your fly zip/buttons are made of before going out in a thunderstorm...

[Derek ^]

Haven't heard that. I have heard that if lightening strikes a sappy tree the tree explodes. Just to add another level of piquancy to the experience.

DG

[dennis]

You would be safe(ish) in a plastic bath as long as you don't stick anything in the appliance.

A metal bath is probably more dangerous as it gives an earth path that you are in contact with so some current will flow through your body. Your body is probably a better conductor than the water unless you have a lot of bath salts in the water.

(Who said earths are safe?)