Help! Shore Power Problem

[Petronella]

Hi

Shore power to Mehalah in Panama was working fine. Shore power now we are in Australia is no longer working. We can't work out what is wrong

Here is the setup:

- Shorepower lead from pedestal to boat.
- Cable from boat to three way switch (Off/Generator/Shorepower).
- Cable from threeway switch to consumer box with GFI and two circuit breakers, one to water heater (A), the second to every other 240 appliance (B).

This is what happens:

As soon as the GFI breaker is set to On the pedestal breaker trips. This happens even if the two circuit breakers (A and B) are switched off! And even if one or both are physically disconnected. The only time the pedestal breaker does not trip is if the entire consumer unit is physically disconnected!

What we have tried:

- Replacement Shorepower lead
- Bypassing the threeway switch
- Bypassing the GFI
- Every combination of breaker/GFI settings we can think of.

The result is always the same. GFI On, pedestal breaker trips.

What is going on? Thanks for your help. This is my last chance before forking out for a proper marine electrician.

 

[Halo]

Have you tried a different pedestal?

 

[PaulRainbow]

Hi

Shore power to Mehalah in Panama was working fine. Shore power now we are in Australia is no longer working. We can't work out what is wrong

Here is the setup:

- Shorepower lead from pedestal to boat.
- Cable from boat to three way switch (Off/Generator/Shorepower).
- Cable from threeway switch to consumer box with GFI and two circuit breakers, one to water heater (A), the second to every other 240 appliance (B).

This is what happens:

As soon as the GFI breaker is set to On the pedestal breaker trips. This happens even if the two circuit breakers (A and B) are switched off! And even if one or both are physically disconnected. The only time the pedestal breaker does not trip is if the entire consumer unit is physically disconnected!

What we have tried:

- Replacement Shorepower lead
- Bypassing the threeway switch
- Bypassing the GFI
- Every combination of breaker/GFI settings we can think of.

The result is always the same. GFI On, pedestal breaker trips.

What is going on? Thanks for your help. This is my last chance before forking out for a proper marine electrician.

If the breakers in the consumer unit are single pole, open the consumer unit and disconnect the neutral to the water heater.

 

[Boater Sam]

You could inadvertently have a neutral to earth connection,,,,,,,,like the bonding on an inverter? Is your 3 way switch double pole?

Is the supply center tap to earth?

 

[VicS]

You could inadvertently have a neutral to earth connection,,,,,,,,like the bonding on an inverter? Is your 3 way switch double pole?

Is the supply center tap to earth?

Agreed........... A neutral to earth fault .............Water heater element a likely culprit, hence PR 's suggestion, together with the on board GFI being less sensitive, or slower to trip , than the pedestal GFI, or even faulty !

Cannot explain why there was no problem in Panama though.

 

[PaulRainbow]

You could inadvertently have a neutral to earth connection,,,,,,,,like the bonding on an inverter?

Not likely to be a connection, as such, but very likely to be a neutral to Earth leak. Inverter bonding is done at source, prior to the RCD

Is your 3 way switch double pole?

It has to be double pole.

Is the supply center tap to earth?

Shore power, centre tapped ?

 

[PaulRainbow]

Agreed........... A neutral to earth fault .............Water heater element a likely culprit, hence PR 's suggestion, together with the on board GFI being less sensitive, or slower to trip , than the pedestal GFI, or even faulty !

Not sure why, but almost every time an RCD trip, or a short onboard causes an RCBO to trip, it trips on the pontoon.

Cannot explain why there was no problem in Panama though.

Sods law, just to confound one.

 

[Graham376]

You could inadvertently have a neutral to earth connection,,,,,,,,like the bonding on an inverter? Is your 3 way switch double pole?

Is the supply center tap to earth?

Yes, that happened to us after having installed a new inverter which appeared to have earth and neutral bonded. Unplugged from the inverter and shore power worked OK.

 

[Graham376]

Not sure why, but almost every time an RCD trip, or a short onboard causes an RCBO to trip, it trips on the pontoon.

Sods law, just to confound one.

Was the same with our garage. Garage consumer unit has RCD but was tripping the one in the house consumer unit which fed it, not the garage one.

 

[PaulRainbow]

Yes, that happened to us after having installed a new inverter which appeared to have earth and neutral bonded. Unplugged from the inverter and shore power worked OK.

Something wrong with that installation Graham, or the inverter. Fixed installation inverters should have Earth and neutral bonded at source, but that shouldn't trip shore power, as when on shore power the inverter should be isolated by a double pole changeover switch. Perhaps your switch was only single pole ?

 

[Graham376]

Something wrong with that installation Graham, or the inverter. Fixed installation inverters should have Earth and neutral bonded at source, but that shouldn't trip shore power, as when on shore power the inverter should be isolated by a double pole changeover switch. Perhaps your switch was only single pole ?

No changeover switch fitted at the time, it was a very recent part installation. Double pole switch fitted afterwards.

 

[jdc]

...

Shore power, centre tapped ?

This is not an attempt to answer the OP's query, but just a by-the-way. But I have seen something equivalent to centre tapped mains. In Brazil they have 127V three-phase, which is served up on marinas as single phase to yachts expecting 110V and between two phases (so 220) for those wanting 230V.

Rather different to UK practice, and it puzzled me greatly as my boat's earth polarity fault neon always lit (even when I'd swapped L & N in the 16A plug - which I'd had to do several times in the Canaries and Cape Verde).

 

[jamie N]

Water ingress into pedestal during voyage?

 

[starfire]

Shore power, centre tapped ?

It was like that on some pedestals, in Manoel Island, Malta around 2001. Caused no end of fun.

 

[PaulRainbow]

This is not an attempt to answer the OP's query, but just a by-the-way. But I have seen something equivalent to centre tapped mains. In Brazil they have 127V three-phase, which is served up on marinas as single phase to yachts expecting 110V and between two phases (so 220) for those wanting 230V.

Rather different to UK practice, and it puzzled me greatly as my boat's earth polarity fault neon always lit (even when I'd swapped L & N in the 16A plug - which I'd had to do several times in the Canaries and Cape Verde).

It was like that on some pedestals, in Manoel Island, Malta around 2001. Caused no end of fun.

Interesting, never come across it, thanks for sharing

 

[Refueler]

Thoughts spring to mind of ENR ......

 

[VicS]

Thoughts spring to mind of ENR ......

Dont see it if the GFI is tripping with both circuit breakers open. Would need some load wouldn't it unless there was also a neutral to earth fault.

Perhaps you could explain.

 

[William_H]

As far as I know 240v power systems in Oz and earthing /neutral are similar to UK system. Probably vastly different to US and like countries.
I woulds suggest try with water heater disconnected. Typical failure mode for imersion element is corrosion through outer coating causing short circuit of element to ground. of course if it is a 120v element that would cause over current. ol'will

 

[Petronella]

If the breakers in the consumer unit are single pole, open the consumer unit and disconnect the neutral to the water heater.

Success Paul

Thank you!

Not the water heater but poor installation of a new socket on my part to drive our Starlink.

Now all up and running!!

Thanks to all for your assistance.

 

[Refueler]

Dont see it if the GFI is tripping with both circuit breakers open. Would need some load wouldn't it unless there was also a neutral to earth fault.

Perhaps you could explain.

Wasn't meant as a possible for this guys problem ... it was all the talk about earth etc - just reminded me of discussions over here about how to ground my house - as it needed rewiring from the old Soviet system ...