Electrical leak

Seven Spades

Seven Spades

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When my boat was on the hard, I could detect a tingle through the p-bracket when the charger was switched on. No problems when any other circuit was switched on just the charger. The charger is charging the batteries. I have no ode what would be causing this to happen, but now my boat is on the water I don't want to charge the batteries unless it causes problems. What should I look for?

Just for clarification, I was not getting a 240V belt, it was a tingle I could feel un the inside of mr wrist. I could not feel it with my fingers.
 
Seven Spades said:
When my boat was on the hard, I could detect a tingle through the p-bracket when the charger was switched on. No problems when any other circuit was switched on just the charger. The charger is charging the batteries. I have no ode what would be causing this to happen, but now my boat is on the water I don't want to charge the batteries unless it causes problems. What should I look for?

Just for clarification, I was not getting a 240V belt, it was a tingle I could feel un the inside of mr wrist. I could not feel it with my fingers.
Click to expand...

You should check the earthing all the way from your shore power plug , the lead, the plug and socket that form the connection to the boat, the galvanic isolator, the connection to the consumer unit and to the charger/on-board sockets. Also check the bonding between the shore power earth and the DC negative and the anodes.

You should also check that your RCD works correctly.

If you are using a portable charger it would also be sensible for it to be PAT tested.

The leakage may be due to the type of power supply in the charger but you should not feel it if the earthing is sound.
 
I have Googled galvanic isolator and I have not seen one of those on my boat. Are these sometimes built into chargers or were they not fitted to boats circa 1996?
 
I don't think I have an isolator in board, I haven't seen one but that dos not mean it is not there. If I fit one and there is already one in the circuit will that cause problems? Is it likely that citing an isolator is going to fix the problem. How can I check to see if the problem goes away? I need to put a multi meter between two points but what two points? Do I wire a plug with just an earth wire and then use a volt meter to see if there is a current between earth and the p-bracket, is that the way to do it?
 
Suggest you do as VicS says as sounds like a faulty charger (possibly), the fault (or poor design) perhaps not being detected by the RCD (assuming you have one). Galvanic isolation is primarily intended to prevent stray earth currents from causing electrolysis and eating away at metal areas in contact with the water, and typical electrolysis related voltages are likely to be very low, perhaps less than 1 volt, and unlikely to be detected by our bodies.
 
Seven Spades said:
I have Googled galvanic isolator and I have not seen one of those on my boat. Are these sometimes built into chargers or were they not fitted to boats circa 1996?
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Several responses to that already.

I included it in the list of things to check because they can go open circuit and therefore break your shore power earth connection.......... if you had one.

If you normally leave shorepower connected, even if not in use, a GI is strongly recommended to avoid excessive rate of loss of anodes.
 
The tingle is an AC voltage difference between your boat's earth and the hard standing earth. They should be at the same potential so a long a tedious job of checking with a voltmeter is in order. That should have been your first test.

We had the same problem here twice in Turkey. 25 volts between our prop shaft and the ground. This also showed up as 25 volts between the AC Earth and Neutral wires. If this is the case it is a marina issue with a bad earth somewhere. It took me two hours to persuade them it was their problem not my boat! It's worth mentioning that here it seems to be such a common problem that all boats have an earth wire from the prop to a nail in the ground to stop people getting tingles.

If you are doing the tests yourself be very careful and read Nigel Calder's book first. Messing with AC can kill you or someone else if you get it wrong. Lots of drownings now in marinas are being attributed to AC leaks caused by faulty equipment, or worse by bad installations. One boat owner killed his wife and daughter by miss wiring his shore power cable! It only takes a few mA to kill.
 
In terms of electrical safety, you must have an RCD aboard, not just rely on a shore supply one, and an "isolator" is simply that, a switch intended to turn off the supply, and does not offer any running protection. As for RCD tests, they do have a self test button, but relies on RCD being correctly installed, and only sure way of testing, is to inject a controlled fault current from a suitable tester.
 
As I said it is charger related because when I switched the charger off the tingle went away even if all the other AC circuits were switched on, so does that rule out your faulty marina earthing theory or not?
 
With respect Seven Spades, sounds like you should get an electrician to look at your installation generally (presume it's a fixed installation, not just plugged into an extension lead from shore power socket?) in terms of safety. Electrician will also have suitable test equipment.
 
What on earth do you mean by that comment? I don't know what you mean by a "fixed installation" as against an extension lead. I do use a lead to plug my boat in but so does everyone else.
 
Seven Spades said:
What on earth do you mean by that comment? I don't know what you mean by a "fixed installation" as against an extension lead. I do use a lead to plug my boat in but so does everyone else.
Click to expand...

Do you have a permanent onboard AC installation with a consumer unit with RCD and MCBs and an inlet "socket" and a lead that connects from that to the pontoon supply or do you use an extension lead just like you do in the garden at home
 
Seven Spades said:
What on earth do you mean by that comment? I don't know what you mean by a "fixed installation" as against an extension lead. I do use a lead to plug my boat in but so does everyone else.
Click to expand...

If you have a socket on the stern of your boat that you connect the shore power lead to and that leads to a switch and RCD inside the boat, that is a fixed installation. If you have one of those, I suggest you get an electrician to check it over. If you use a long extension cable to bring power on board to a battery charge plugged into the end of if you don't have a fixed installation but you should still get an electrician to check things over!
 
Do yourself and us a big favour and buy a digital voltmeter - about £10 - and measure the voltage that was giving you the tingle. If it's around 20 volts AC that's probably an earth problem somewhere, if it's 240 volts AC that means your charger is connecting the Live wire to your boat DC negative.!!!!!!
 
Seven Spades said:
As I said it is charger related because when I switched the charger off the tingle went away even if all the other AC circuits were switched on, so does that rule out your faulty marina earthing theory or not?
Click to expand...

Its charger related but it is not necessarily due to a fault in the charger. It could be a characteristic of the type of power supply in the charger. Having the chrger tested could be sensible though.

However if the earthing of the boat were perfect I'd not have expected the tingle you experienced. It may not be any serious problem if you only felt this on a very sensitive area.
However the uncertainty makes it sensible to have the system checked
 
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