Some Advice, a curious series of events?

[flameport]

Now, suddenly one of the three storage heaters seems to be on the blink. It seems to be tripping one of the RCBOs.

That is unusual, storage heater elements are not normally connected to earth, so any leakage current from the element casing has to go through the bricks, which are very low conductivity as all the moisture is driven out when they are heated, and the bricks are not normally in contact with any metal parts of the heater frame either.
Damaged wiring is certainly a possibility. Could be tripping on overload, depending on the RCBO rating and the size of heater.
Further investigation is required.

 

[dishman]

I will certainly get someone out to check.

I think it is rated 16a as per the previous MCB which never had trip issues.

It was only swapped to RCBOS a few weeks ago.

These RCBOs are niglon branded. Which I am told is a pretty bargain basement make.

I came across another supposition on another forum (not my post). The chance that the MCB is tripping if they are not great quality or old, overheating potentially when positioned next to each other.

https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=64684

I will still get someone out to check it though after I take a glance at the fuse spur connections.

 

[JohnW2]

It was only swapped to RCBOS a few weeks ago. .... These RCBOs are niglon branded. Which I am told is a pretty bargain basement make.

Yes, I forgot to mention a third possibility - as well as a fault in the heater or in the circuit's wiring, it could simply be an iffy RCBO (tripping when it shouldn't) - and what you've just written perhaps makes that more likely!

Kind Regards, John