Will 2 out of 3 Phases Trip a 3 Phase Breaker?

[Kelvin]

Be careful how you word this, you may know what you mean here but OP isn't an electrician. Loss of a phase through a three phase mcb alone will not cause it to trip whether from the supply side or broken wire load side, having said that and as you noted in previous post it may cause excessive current rise in other phases and this will depend on the load and its characteristics i.e. if a 3ph motor connected then it will 2phase on start-up giving high current spike on the stalled motor until it is detected by the motor overload or mcb or if poorly designed install/control circuit then until the motor catches fire and shorts

Oga does your breaker have overload function or capacity. If yes then single phasing automatically gives more load to the remaining 2 phase which depending on the breaker's rating as against the load can either trip or withstand the load. Hence, on installation every breaker rating should be a little more than the load that is given to it.

 

[Darkwood]

Oga does your breaker have overload function or capacity. If yes then single phasing automatically gives more load to the remaining 2 phase which depending on the breaker's rating as against the load can either trip or withstand the load. Hence, on installation every breaker rating should be a little more than the load that is given to it.

This thread is 8 yrs old, I can confidently say it has been resolved imho, please cheque the time stamps on thread/posts before responding.

 

[ruston]

This thread is 8 yrs old, I can confidently say it has been resolved imho, please cheque the time stamps on thread/posts before responding.

It was nice to see some old names though, especially Engineer54.

 

[Rockingit]

It was nice to see some old names though, especially Engineer54.

Another RIP, sadly.