rogerthebodger
Well-known member
Yes but why is it considered that reverse is unsafe.
Is it unsafe to disconnect the boat end of the shore power cable before the supply side.
Electrocution risk in marinas
- Thread starter Beneteau381
- Start date
Yes but why is it considered that reverse is unsafe.
Is it unsafe to disconnect the boat end of the shore power cable before the supply side.
rogerthebodger
Well-known member
I have RCD on my boat but that is only half the story. as th RCD works on a difference in current in the line and neutral lines through the RCD.
This difference in current has to go somewhere which should be down the connected earth cable which should be connected correctly.
An alternate patch is through the ground via the water / ground back to the earth spike connected to the neutral supply at the substation transformer.
If the r is a proper wired protective earth back to the sub station and there is a fault that connects the liv to the earth wire the RCD should instantly trip shutting off.
If thi wired protective earth is not connected correctly and the case to live fault accrues and a person touched the metal case the leakage current will pass to the earh spike at the substation eart spike via the person / water / earth causing the RCD to trip
The problen is if ether/both protection earth path is not connected this is where a danger to a person toudhing the metal case of a faulty case or a swimmer in the water could get electrized
I have also fitted a red and green neon indicators in my mains supply line.
RED between neutral and incoming earth line this on indicates a reverse line and neutral connection.
GREEB between live and incoming earth line. If this is not on there is a protective earth fault such that the RCD would not trip straight away with a line to metal case fault
Tha same can apply with internal mains power suppliers like inverter and generators.
pmagowan
Well-known member
Because you are surrounded by electrolyte and carrying a plugged in lead that could easily find itself in some water. The point is not to have a live cable which is achieved by unplugging the shore end first. You should not rely on the shore protections
rogerthebodger
Well-known member
Yes I can see that.
The shore protection should be in order because it it is not the marina would be liable for any injury or loss of lfe.
This is why I have indicators to tell ne if the shore power is dangerous
A workman I had on my boat before I had shore power was using my little Honda suitcase generator and dropped the power lead and running drill in the marina. The over load on thr generator did not trip and there was no CD or neutral earth connection but there was a case to water connection.
From then on I added an RCD into the engine power lead and a neutral earth connection at the generator outlet before (engine side the RCD
Last edited:
Momac
Well-known member
Deleted
pmagowan
Well-known member
The thing is the pins are not exposed to a finger etc but the socket is at much higher risk than the ones in your house or even garden. It can easily end up in the drink or a puddle of sea water on deck and then you are relying on the shoreside protections to prevent electrocution. I suppose it is also a potential that you drop it into some sea water and only the neutral and live are exposed thus creating an electrocution risk that only overvoltage protection will stop rather than the rcb. Bit of a 'Final Destination' risk that though
Momac
Well-known member
I deleted but you beat me to it.
Will bear this in mind but would suggest potentially less safe rather than unsafe should be applied.
Will bear this in mind but would suggest potentially less safe rather than unsafe should be applied.
pmagowan
Well-known member
I think you are splitting hairs a bit there. Walking around on an unstable object with multiple trip hazards, slippy surfaces and surrounded by electrolyte while carrying a live wire is a bit unsafe, IMO, but is definitely less safe than just unplugging said wire.
Daedelus
Well-known member
I added a couple of neons to my consumer unit on the boat with green alight when power was on and the amber came on if the polarity was reversed. I found this in a French marina and used a polarity reverser cable and plugs - very clearly and obviously labelled so no-one used it unintentionally.
mjcoon
Well-known member
Quite. People who do not understand risk analysis, however intuitive, or effort trade-offs, are heading for the Darwin Awards...
rogerthebodger
Well-known member
If you drop a live power cable or power tool into the sea nect yo your boat what does the forum think what should happen
My view is the RCD on the marina supply post should trip straight away
If it does not the marina electrical installation is unsafe IMHO
The question is what about onboard inverter or generator and what should happen if a power tool or extension is dropped into the sea
My view is the RCD on the marina supply post should trip straight away
If it does not the marina electrical installation is unsafe IMHO
The question is what about onboard inverter or generator and what should happen if a power tool or extension is dropped into the sea
pmagowan
Well-known member
It may be unsafe. When do you suspect it was last tested? What happens if live and neutral are the only 2 terminals that come in contact with the water, or are the first. What happens if there is an earth fault in the cable? I will use an RCD but I wont trust my life to one and I certainly wouldn't trust my life to an electrical connection on a marina and/or/boat. The safety feature is the fallback, not the thing you rely on.
rogerthebodger
Well-known member
Ok how are you going to protect yourself and anyone else in your local if you accidently drop a live and neutral only extension lead in the sea
What will trip to remove the power supply and how will that happen
pmagowan
Well-known member
I think the whole point is I will not be carrying a live power lead because the marina end will be unplugged before I unplug the boat end! I ill also plug in the boat end before plugging in the marina end and thus my cable will always be completely unexcited by jiggling electrons when it is at risk of being dropped.
mjcoon
Well-known member
It really should not make a difference whether the earth lead in the cable gets connected to sea water! (Earth and water does not equal fire, or something ;-)
rogerthebodger
Well-known member
The point of the earth either wired or via the sea is that any leakage currency into the sea wll bypass the neutral line back to the sun station causing an imbalance in the current in the live and neutral lines in the RCD which wi cause the RCD to trip the cutting the mains supply to the cable that is in the sea making the mains supply safe.
This face is also the case with inverters and generators which need an RCD and a current path back to the neutral supply of the power device
Momac
Well-known member
Consideting all the hazards it's bit surprising some people go boating.
At my home berth a new shore power system was installed a few years ago. The electrical power is cut off when the cable is unplugged. The power supply can only be reinstated with the cable connected.
Of course that's not the case at most marinas.
At my home berth a new shore power system was installed a few years ago. The electrical power is cut off when the cable is unplugged. The power supply can only be reinstated with the cable connected.
Of course that's not the case at most marinas.
rogerthebodger
Well-known member
Unplugged from the marina supply or unplugged from the boat ?
Frank Holden
Well-known member
If live and neutral are wired 'A about face' it can get pretty ugly. My boat was on shore power and out of the water just after I bought her and the propellor gave me a hell of a bite.
It was Thailand... a fellow sailor walking past sez ' I know how to fix that' and while standing in wet grass and wearing sandals proceeds to rewire the live shore socket!!!
In Unzud the plugs and sockets - the blue ones - are required to have a 'see-through' section that lets you see on the instant if they are wired correctly.
I would never dream of going in the water in a marina - its not just the stray currents - blind mullet are also a consideration.
It was Thailand... a fellow sailor walking past sez ' I know how to fix that' and while standing in wet grass and wearing sandals proceeds to rewire the live shore socket!!!
In Unzud the plugs and sockets - the blue ones - are required to have a 'see-through' section that lets you see on the instant if they are wired correctly.
I would never dream of going in the water in a marina - its not just the stray currents - blind mullet are also a consideration.
Halo
Well-known member
I saw a yacht set off while still plugged in. After pulling the bollard over the wire broke and went into the oggin. It fizzed for a few minutes before the electricity cut out. This was a newish system in Scotland. I would not rely on any sort of cut off rather do the right thing and unplug at the pontoon end. I suspect there was a substantial potential difference in the water so not good news for swimmers
