wonkywinch
Well-Known Member
Think we're just at cross purposes here. I understand that but was speaking figuratively about a 63A device in isolation, not the specific set up the OP has.
Shore power circuit breaker size
- Thread starter Parmesan
- Start date
Alex_Blackwood
Well-Known Member
With you on that one
It's an RCD not a MCB. As per#8 I would fit a 16amp RCBO in it's place.
Boathook
Well-Known Member
Replace the whole lot with a double pole master switch and double pole RCBO's suitably rated for the circuits. Possibly 16 and 6 amp.
VicS
Well-Known Member
With you on that one
Why?
Why change anything if all that is required is power for a kettle or fan heater and a battery charger?
I am sure that by now the OP has realised his misunderstanding of the 63 amp rating of the RCD, which was his initial concern.
st599
Well-Known Member
Is the suggestion about moving to double pole not more to do with visiting foreign ports. In countries which use double pole protective devices, there's less care taken with phase and neutral.
PaulRainbow
Well-Known Member
If he turns a kettle and fan heater on at the same time it will trip the shore power marina side. Swapping the 32A MCB for a 16A one should cause the onboard MCB to trip. Bit more convenient and safer than relying on the marina trips.
VicS
Well-Known Member
I had not noticed that he said it was 32ampIf he turns a kettle and fan heater on at the same time it will trip the shore power marina side. Swapping the 32A MCB for a 16A one should cause the onboard MCB to trip. Bit more convenient and safer than relying on the marina trips.
! Agreed that should be swapped out for a 16 amp one. ( unless cabled and fitted with connectors for a 32 amp supply)
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Dockhead
Well-Known Member
Nothing wrong with 32A shore power circuit protection, if the whole circuit, including cabling from shore power inlet to main panel, and the connections, and the shore power cable, is rated for that. In fact that's the correct way to do it.
My shore power circuit is protected with a 32A RCD and breaker. All the cabling is rated for that and the boat-end connector is rated for that. The shore power cable is rated for that.
If the pedestal is less, it has its own breaker with appropriate rating. It's rare to find more than 16A rated supply in this hemisphere, but it exists. I use commercial harbours occasionally and have adapters for larger supplies, and so occasionally get a 32A supply.
Branches in your boat's electrical system are each protected by its own breaker sized to protect THAT BRANCH.
N.B. that those breakers don't protect the devices you connect -- just the wiring and connections.
That's how overcurrent protection works.
My shore power circuit is protected with a 32A RCD and breaker. All the cabling is rated for that and the boat-end connector is rated for that. The shore power cable is rated for that.
If the pedestal is less, it has its own breaker with appropriate rating. It's rare to find more than 16A rated supply in this hemisphere, but it exists. I use commercial harbours occasionally and have adapters for larger supplies, and so occasionally get a 32A supply.
Branches in your boat's electrical system are each protected by its own breaker sized to protect THAT BRANCH.
N.B. that those breakers don't protect the devices you connect -- just the wiring and connections.
That's how overcurrent protection works.
Dockhead
Well-Known Member
If he's got kettle and fan heater on the same ring main branch circuit, then the branch circuit breaker will deal with that, no?If he turns a kettle and fan heater on at the same time it will trip the shore power marina side. Swapping the 32A MCB for a 16A one should cause the onboard MCB to trip. Bit more convenient and safer than relying on the marina trips.
On my boat, the ring main circuit is protected with a 16A breaker.
If he's got 32A rated wiring from shore power inlet to main panel, why would he worry about the pedestal? The pedestal can take care of itself, no?
In any case, I feel it's a good idea to monitor volts and amps in the AC system to keep an eye on all this. I have two cheap Chinese V/A meters on my instrument panel which display values for shore power/generator and then for the main panel, which may be different from one another as there is a charger/inverter between them. I find this very useful -- might be a good tip for someone. I actually wish I had a third one for the ring main circuit.
PaulRainbow
Well-Known Member
Only if the boat is plugged into a 32A supply.
It doesn't matter how your boat is wired, what matters for the OP is how his boat is wired.
His RCD is rated at a max current of 63A, so offers no over current protection, that is provided by the MCBs. He has two socket outlets protected by a 32A MCB, connected to a 16A supply, so again, no over current protection, relying on shoreside equipment for that. This is incorrect.
The pedestal breakers should only be considered as last ditch protection, to protect against faults between the pedestal and the onboard protection, or in the case of faulty protection onboard. They are not there for routine over current protection for the boat.
So fitting a 32A MCB for the socket outlets is incorrect then.
FYI the pedestal beside my boat has 2x32A outlets, as does every hammerhead in my marina.
So a 32A MCB for two outlets, connected to a 16AS supply is wrong.
Thanks for the lesson, but the OPs MCB is incorrect.
PaulRainbow
Well-Known Member
No, it will not. See post #26
"If he turns a kettle and fan heater on at the same time it will trip the shore power marina side. Swapping the 32A MCB for a 16A one should cause the onboard MCB to trip. Bit more convenient and safer than relying on the marina trips."
Again, no. See above.