RCBO intermitent trip overnight

Hi - have had a Mira shower running back to an MCB for 2 yrs and working fine. Recently replaced the MCB with RCBO (30mA) for extra safety/security. Runs shower fine for ages; no faults/stipping. However, at other times during day/night when shower has not been in use, the RCBO trips (for no aparent reason). Any thoughts?

Also, I understand an RCD is not requied legally, tho obviously desirable for safety. Is this still true? Many thanks.

yes its true though i wouldn't personally wan't to fit a shower without one.

possiblly an intermittent N-E fault somewhere in the shower cuircuit. i'd say start by checking all cables and connections that you can get at.

another posisbility is that someone has borrwed a neutral from the shower cuircuit.(many rcbos don't isolate the neutral so you won't notice until you go to try and use the shower that something has tripped it).

DC Sence RCBO's can trip when you have an earth fault on the installation.

A lost neutral supply to the RCBO will also trip most makes.

Plus what was said above.

going back to what plug said about a borrowed neutral, you could disconnect the neutral to the ahower circuit at the cu (put it in a terminal block out the way, and leave the rcbo switched off, turn off main isolator while working in cu btw) turn on isolator, make sure all breakers except the shower rcbo are on, and go round your house and see what else apart from the shower doesn't work