ELECTRICAL INSTALLATIONS NEAR WATER - ELECTRIC SHOCK DROWNING

[marconi]

Recently there was a topic onwhether or not to bond and earth a mobile aquarium. I did some more research on what happens to people when they are in electrified water. There is quite a bit on what happens on US web sites. The problem is not only electrocution but 'electric shock drowning' whereby the body's nervous system is interfered with by electric currents flowing through it resulting in paralysis in the water. The problem is exacerbated by the large effective contact area between the electrified water and the body's skin and worse in fresh water than salt water because the latter is a better conductor than the body - so more currents flow around the body than through it. In neither case is the current zero. Of course the body has to be in a significant electric field which depends on proximity to and voltage of the electrode in contact with the water.

I thought those doing electrical installation work in ships and boats, marinas and harbours might be interested to hear about it. Note the suggested warning signs illustrated in the web site.

See:

Electric Shock Drowning Prevention Association - https://www.electricshockdrowning.org/

 

[Chris1234]

We have a lot of water tanks at work.
I’ll read it later, thanks

 

[Deuce]

Recently there was a topic onwhether or not to bond and earth a mobile aquarium. I did some more research on what happens to people when they are in electrified water. There is quite a bit on what happens on US web sites. The problem is not only electrocution but 'electric shock drowning' whereby the body's nervous system is interfered with by electric currents flowing through it resulting in paralysis in the water. The problem is exacerbated by the large effective contact area between the electrified water and the body's skin and worse in fresh water than salt water because the latter is a better conductor than the body - so more currents flow around the body than through it. In neither case is the current zero. Of course the body has to be in a significant electric field which depends on proximity to and voltage of the electrode in contact with the water.

I thought those doing electrical installation work in ships and boats, marinas and harbours might be interested to hear about it. Note the suggested warning signs illustrated in the web site.

See:

Electric Shock Drowning Prevention Association - https://www.electricshockdrowning.org/

I believe that was my thread, regarding my tank..

I would say salt water is actually more dangerous in a swimming pool environment, simply because it is a far better conductor (It helps the current reach you without massive voltage drop before it does). The only time I would say otherwise is if the shock was direct (for instance, from touching a live submersible pump housing).

Most pools are effectively isolated so other than a tingle 'something is odd here...' the current has nowhere to go, through the water or through the swimmer - and in anycase, water is not a fantastic conductor at the best (worst) of times anyway. The biggest danger in that scenario is the person leaving the live pool water and making contact with something that does have a ground connection. In that crossover instance, they become the route to earth.

The key thing you have picked up on though is the secondary risk of drowning. Some people react very badly to even low current, and in water, anything affecting your nervous system is of course potentially dangerous. In the end, this is just one of a number of reasons you should never enter any water alone. People are found drowned in rivers all the time with the only evidence of anything being wrong a simple bruise to the head = they slipped, knocked their head and went under whilst unconscious. There are endless obscure reasons for a person ending up face down in water, but all are addressed by having a second person on standby to drag them out before it's too late.

I can't be bothered to google it but I think the all time reason for drowning is a knock to the head (don't run round the pool...), followed by pre-existing conditions disabling a swimmer, and then thermal shock. I imagine electrocution is a fraction of a fraction of a %.

 

[marconi]

I think the other key point is not to go in the water near boats in a marina which have mains electrical supplies.

 

[telectrix]

I think the other key point is not to go in the water near boats in a marina which have mains electrical supplies.

they also have nasty swirling things called propellers that may cut your bits off.