MCCBs

Very good explanation from mapj1 - the only thing I would point out is that with the 'death or glory' fuse, don't put it on circuits that you can't afford to lose. Probably not an issue in most domestic installations but may cause problems in some circumstances.

Cascading protective devices while maintaining discrimination is a fine art. If you want more information about it I found a very good explanation on the Schneider website at:

 https://www.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/289000/FA289962/en_US/Discrimination,cascading%20and%20enhanced-discrimination-by-cascading.pdf

though I imagine other major circuit breaker manufacturers will have similar documentation and would recommend looking at what some others say as well to make sure you are not being forced down a particular manufacturers route. Generally if you can get both time and current discrimination you will be fine, though as said above, at higher currents the time discrimination is a bit of a problem on miniature circuit breakers (MCCBs and ACBs are generally less of a problem but used at higher fault levels than we are talking about here - I have seen them used on fault levels down to about 10-15kA but not below).

Alasdair

Very good explanation from mapj1 - the only thing I would point out is that with the 'death or glory' fuse, don't put it on circuits that you can't afford to lose. Probably not an issue in most domestic installations but may cause problems in some circumstances.

Cascading protective devices while maintaining discrimination is a fine art. If you want more information about it I found a very good explanation on the Schneider website at:

 https://www.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/289000/FA289962/en_US/Discrimination,cascading%20and%20enhanced-discrimination-by-cascading.pdf

though I imagine other major circuit breaker manufacturers will have similar documentation and would recommend looking at what some others say as well to make sure you are not being forced down a particular manufacturers route. Generally if you can get both time and current discrimination you will be fine, though as said above, at higher currents the time discrimination is a bit of a problem on miniature circuit breakers (MCCBs and ACBs are generally less of a problem but used at higher fault levels than we are talking about here - I have seen them used on fault levels down to about 10-15kA but not below).

Alasdair