Yes but this would trip the breakers every time they switch on if it were the case.It could be the switch-on surge of the heat lamps is tripping the breakers.
This will be many times the running current but will last only momentarily.
If the MCB's are type B, then fitting type C should help if this is the case.
Frank
Not always, if it's right on the limit of the magnetic park of the breaker then sometimes they will trip and other times they wont. However, as RF suggested, a clamp meter is the correct way to proceed before changing the MCBs.
