Hello,

You can read information in internet like here. But I think if heater power is 3000 Wats and you have incoming 3 phases (415 Volts) it take about 7.5 Amps. So I will put 10Amps circuit breaker

Dear Pauly

as it mentioned in later posts, it is better you specify the connection method and number on heater elements you are using, so it would be easier to recommend CBs.

I suppose you are using 3 elements in start connection, so I calculated the max current (when we talk about heater elements , it mean that our load is resistive and we can simply calculate the current from P=V*I formula) for two case which I have draw in the attached file and also I have mentioned suitable circuit breaker for each case.

You should consider that usually for protecting heater elements simple circuit breakers (miniature circuit-breaker) are enough and there is no need to use motor protection CBs.

Hello ALI_N23, 

Please refer your attached snap (shown in star connection) from your description, the heaters are connected across two phase, since you mentioned voltage as 415 volt, in such case two heaters will be in-series so total load across two phase will be either 2000 Watt (if 1000 watt per heater) or 6000 watt (if 3000 per heater)

If heaters are connected across phase & neutral then load will be 1000 Kw & in such case current = kw/ 1/sq. root 3 * voltage i.e. 1000/(1.732*240) = 2.4 A

Please check.