my question is why every morning where i switch on geyser after some time main single phase 32 amp two pole breaker is tripping.if i use afternoon or evening its working properly and some time breaker was not tripping.i install new geyser then also i got same problem. sometime breaker trip and sometime working properly. electrician check lose connection but there no any lose connection at all.this issues of that 32amp MCB ?how can i find out this problem and solve?
Normal breakers (not GFCI/RCBO or AFCI) trip because you are drawing too much power.
If it sometimes trips when you turn it on, and sometimes doesn't, that means either you were using more power elsewhere on that circuit during the times it tripped, or it is right at the edge of what that circuit can handle and it drew more power than usual or was on for a longer time. Or the breaker is defective.
A clamp on ammeter can tell you how much power is being draw on a particular circuit. If you had an electrician out to fix this, why did they check for lose connections and then stop looking?