Lightning strike on a swimming pool

[ekmdgrf]

I love a good Friday teaser and as it's Friday, here's one:

Once upon a time I used to go swimming in an open-air pool. One afternoon there was a flash of lightning and a frantic evacuation of the water by pool staff. As I stood by the side of the pool, a good 6' closer to the source of the aftermentioned HV spark, I did start to wonder if I'd be better off staying in the pool, on that rational that liquids tent to congregate in the lowest part of a given area and this may be a wiser place to be than standing up mimicing a lightning rod. What then, I reasoned would happen if the lightning did strike the pool? I've found it hard to answer that question although the thoughts involved Chlorine ions and a fairly low ressistance pool content against a fairly highly resistive human body. Where does the current go? A well-know Internet search engine suggestions a radial dispursment across the surface of the water, from the centre of the strike.

The only reports that I could find of this happening were a couple of people who were killed by a lightning strike while sitting next to a pool and also a strike to the surface of a pool in Canada with no reported casualties.

So, in summary:

1) When lightning strikes a pool, where does the current go?
2) What happens if you happen to be in the pool?
3) Are you better off in the pool or standing by the side of it?

 

[Spark123]

1 to earth via any means possible
2 you may get a shock or you may get scalded
3 I'd take my chances out of the water

 

[ban-all-sheds]

1 to earth via any means possible

Mostly from earth up to the cloud, usually.

But it makes no difference to anybody it flows through which direction it's heading...

 

[Spark123]

Conventional lightning

 

[ban-all-sheds]

That's what I was talking about, and conventional current flow.

Which is positive to negative.

With normal lightning the base of the cloud is negative, and a positive shadow is created on the earths surface.

So in a lightning strike the current flows from the earth to the cloud.

 

[viewer]

A great teaser. I think that your thoughts about being a 6 and wet lightning rod out of the water are probably right, but there are lots of stories which suggest that logical-to-the-human-eye-ionisation paths may be very different to the reality. Numerous metal masted boats have been hit on water and many animals are hit around the world, but perhaps a more likely event at an open air swimming pool would be to "downstream" (don't know the proper word) of a strike. I was once touching a metal fence during an electrical storm in Zambia when I was thrown to the ground. I think that the strike had induced a voltage in the fence rather than hit something physically connected (or I wouldn't be here). In another incident, after a potholing trip in Yorkshire I was following a guy carrying the rolled up electron ladder (wire rope sides with aluminium rungs). There was a flash and the next moment he was the other side of the stone wall; fortunately unhurt. Again, the strike could not have hit him, but maybe the induction effect on the ladder - and thus current to earth - was enough to cause his muscles to contract suddenly.

 

[17thman]

i would suggest the water, is the best place to be as long as you did not have your hands on a ladder bolted to earth hence bypassing the insulating ceramic tiling liner. Or indeed dircecly over any metal ducting, or metal filter pipework. Any strike would go through the path of least resistance through such metal accessories. standing on wet ground that is not ceramic around the edge of the pool,whilst wet could prove painful.

I am wondering whether a storm above would cause an electron path from more earthed surrounding land or buildings that a ceramic lined pool of water?

 

[mikeyd]

1) When lightning strikes a pool, where does the current go?
Through the water to ground.

2) What happens if you happen to be in the pool?
Water isn't that good a conductor of electricity as might be thought. If you are standing up in the pool, lie down quickly and float

3) Are you better off in the pool or standing by the side of it?
If I was standing beside it I'd be running away, but to answer the question: floating in the pool.

 

[crystal ball]

If the pool was lined with reinforced concrete would the steelwork make a faraday cage

 

[bernardgreen]

If the pool was lined with reinforced concrete would the steelwork make a faraday cage

No There would have to be a roof as well.

Closest electrical equivalent would be a Leyden Jar

From a previous discussion elsewhere the concensus was there was no fit all answer as to whether being in the water would be safer without knowing exactly how the strike occurred. With a strike nearby being in the water was considered as safer than being out of the water ( blast effect avoided ), but if the strike grounded on the water then being in that water was possibly the worst place to be.

 

[Taylortwocities]

Best place to be is:

sitting on a stool, at the poolside bar with a rum punch in hand.
And watching the fireworks.

 

[Scoby_Beasley]

Best place to be is:

sitting on a stool, at the poolside bar with a rum punch in hand.
And watching the fireworks.

Would that be ekmdgrf in the middle??

Now if the pool was full of pure water I'd jump in. But chlorine, as a compound, loves electrickery.

I'd also rather be sat at the poolside bar, but with a woman in hand, unless rum punch is a euphemism or "yoofernism" I've not heard!!

 

[ericmark]

There are two things that spring to mind.
1 - A lecture about radio aerials and lighting where he pointed out facts like wind direction, sharp corners, and voltage gradient, and that one should never earth the aerial during the storm, as it would then attract the lighting. However providing a leakage path, and spark gap similar to that found in a telephone master socket, was a good idea so you could touch the aerial after the storm, without getting a shock.
2 - Report on earthing of boats, where it would seem you can swim quite close to a boat with an earth fault in sea water without a problem, but in fresh water ones body has less resistance then the water, so going even near a boat with an earth fault can give a lethal shock.

So the chlorine would likely make it better not worse but because your body is so well earthed in the pool, more likely the strike would hit you. So out of the pool and put on insulated footwear as quick as you can, and remove any water off surface of the body I would think best option.

 

[bernardgreen]

My uncle told me of an incident during WWII where a barrage balloon trailer was not connected to it's earth rod. A person climbing onto the trailer when the balloon was aloft was killed by the static built up on the trailer.

I also recall London buses had white rubber insulation on the hand rails on the platform so people getting on the bus didn't get a static shock.

http://hansard.millbanksystems.com/commons/1952/jun/23/buses-london-static-electricity

 

[ericmark]

I seem to remember having to paint tyres with a graphite laden black paint to stop static build-up. But when we went to radial tyres the problem seemed in the main to go away.

I did note that Wellingtons have graphite in the mix to try and reduce static build up so the idea that wearing wellies stops you getting a shock is flawed.