Looking at adding an RCBO to the shore power inlet of our old yacht to get in line with reg.s. It needs to be active on both phase & neutral, and I've come across a couple of pole definitions that I'm not 100% certain of. Can anyone help with actual knowledge (rather than guesses)?
Here is what I think the definitions mean:
 1 Pole: inputs/outputs for both phase & neutral, RCD functions on the difference between currents in phase & neutral, but trips only the phase circuit, overload protection only trips phase circuit
 1+N Pole: inputs/outputs for phase & neutral, RCD functions on difference between currents in phase & neutral, and trips both phase & neutral lines, overload protection only trips phase circuit
 2 Pole: inputs/outputs for phase & neutral, RCD functions on difference between currents in phase & neutral, and trips both phase & neutral lines, overload protection trips both phase & neutral
It's the "1+N" poles which has thrown me.
Anyone with real knowledge care to correct or validate those definitions?