In article ,
Bovvered? writes:

Join us, come to the dark side. How hot is your consumer unit? You'll
have to buy one to find out...

MCBs are all at ambient temperature.
RCBO's are all about 5C warmer, but they do that even with no load.
(Didn't take the front off -- I think the backs of the RCBOs are
even warmer.)

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]