Electrocution risk in marinas

[Beneteau381]

Been thinking a bit and was aware of people saying stray voltage can kill, but how? Surely if you are immersed then how can voltage flow through you?

 

[VicS]

Been thinking a bit and was aware of people saying stray voltage can kill, but how? Surely if you are immersed then how can voltage flow through you?

The danger is greatest in freshwater, possibly only a serious issue in freshwater. It's because the body is a better conductor than freshwater and the current will take the path of least resistance namely through the body.

Sea water is a better conductor so the current there flows through the water rather than the body.

There is a good, more detailed, explanation in Calder's book

 

[Beneteau381]

The danger is greatest in freshwater, possibly only a serious issue in freshwater. It's because the body is a better conductor than freshwater and the current will take the path of least resistance namely through the body.

Sea water is a better conductor so the current there flows through the water rather than the body.

There is a good, more detailed, explanation in Calder's book

Will have a read when I get back to the boat, thanks.

 

[Porthandbuoy]

Always wise to unplug shoreside first and coil the cable back towards the boat.

 

[VicS]

Always wise to unplug shoreside first and coil the cable back towards the boat.

True but ITYWF the question was about stray currents, swimmers and electric shock drowning.

 

[mjcoon]

Been thinking a bit and was aware of people saying stray voltage can kill, but how? Surely if you are immersed then how can voltage flow through you?

Strictly, of course, it is current that flows, just like water... But you are right, it is that moment with one foot on shore and one foot on the boat that you are vulnerable. But jumping is not advised either!

 

[Momac]

I have kept my boat in a freshwater marina since 2008.

The only electric shock issue I have witnessed was not related to the water. The person involved made a cable extension which left the exposed pins of a plug live , which should of course never happen. He unplugged with the other end in the shore power supply and received a shock. He is still alive.

Swimmers in a marina are more likely to be poisoned or cut to sheds by a propeller rather than electrocuted.

 

[pmagowan]

I suppose it is one of the considerations of the American style (and modern European Style) of bonding all external fittings such that earth faults can go into the water. I think the risk is small and with RCD and equivalent protection smaller. The risk from pollution in the marina or being run over etc is likely an order of magnitude higher so not swimming in a marina seems like a good idea

 

[V1701]

Well I think swimming is not permitted in most marinas, it isn't in mine. Been here 13 years, sadly a couple of people have fallen in drunk & drowned & one dog died in a boat fire in that time. I do get in to scrub the prop & rudder a couple of times a year though & I fell in once (not drunk but being a bit stupid). Nobody electrocuted at all as far as I'm aware...

 

[Graham376]

Been thinking a bit and was aware of people saying stray voltage can kill, but how? Surely if you are immersed then how can voltage flow through you?

Don't know the answer but when canals are being drained for maintenance, they use electric wands to stun the fish so they can be netted. Wonder how many volts it would take to stun orcas?

 

[Gsailor]

I would hope ( and thought ) that mcbs reacted so quickly that a shock was not lethal.

Have I been deluded ? (is that the right word? - losing my faculties I fear)

 

[mjcoon]

I would hope ( and thought ) that mcbs reacted so quickly that a shock was not lethal.

Have I been deluded ? (is that the right word? - losing my faculties I fear)

I thought that was the intent. And I think the time cited on my portable RCD is ~1 cycle of 50Hz, which is about as fast as one could expect...

 

[VicS]

I would hope ( and thought ) that mcbs reacted so quickly that a shock was not lethal.

Have I been deluded ? (is that the right word? - losing my faculties I fear)

Not the mcb ( that's an overcurrent protection device ) An rcd ( or rcbo) should trip if leakage into the water occurs even before any swimmer is involved.
There is more information in Calder's book under the "Ground Fault Circuit Breakers and Residual Current Devices" heading

 

[johnalison]

Always wise to unplug shoreside first and coil the cable back towards the boat.

Not only wise but it should be universally applied.

 

[Beneteau381]

Don't know the answer but when canals are being drained for maintenance, they use electric wands to stun the fish so they can be netted. Wonder how many volts it would take to stun orcas?

 

[rogerthebodger]

Not only wise but it should be universally applied.

Not that I am disagreeing with you ut why do you say it should be universally applied.

 

[johnalison]

Not that I am disagreeing with you ut why do you say it should be universally applied.

If the reverse is unsafe, as I understand it is, then unsafe practices should be discouraged.

 

[Trident]

I remember that someone was killed at a marina in North Cyprus, Karpaz Gate, when it first went in to operation because of faulty wiring that put the current through the metal cover strip down the side of the pontoon!

Also some US states ban external (to water) earthing of the boat due to the risk to swimmers even though it is very minimal.

 

[oldmanofthehills]

I thought that was the intent. And I think the time cited on my portable RCD is ~1 cycle of 50Hz, which is about as fast as one could expect...

If they are fitted. Certainly i would not trust greek or turkish wiring and I have seen plenty of rubbish french and english wiring in buildings (builder with electrically qualified son)

 

[Stemar]

If they are fitted. Certainly i would not trust greek or turkish wiring and I have seen plenty of rubbish french and english wiring in buildings (builder with electrically qualified son)

Which is why I have my own RCD on board.