Discrimantion

[Cj24]

Hi all, if u have one of those little 40amp garage boards obv in your garge with a 40amp main switch in it then u have 6amp for lights n 16amp for socket what size mcb would u say it should be on back at main board, it's an in 2.5 armoured

 

[malcolmsanford]

So..dig up the 2.5swa..replace with....6.00mm swa!..stick a 40a mcb on it....to avoid discimination..yes?....or do we live in the real world ..put a 20a mcb on it and know fine well that a 16a mcb will go first in the case of a problem!!..or put it another way, the 2.5mm cable is in the ground..what size breaker do u use ?

Or as Chr!s highlighted way back on post # 9 mix the protection devices Fuse-MCB to give you the discrimination on overload and fault protection.

 

[acvc]

Let's not forget the installation method of the 2.5mm feeding the garage, the possible need to derate :thinking:.

 

[KINKY]

So..dig up the 2.5swa..replace with....6.00mm swa!..stick a 40a mcb on it....to avoid discimination..yes?....or do we live in the real world ..put a 20a mcb on it and know fine well that a 16a mcb will go first in the case of a problem!!..or put it another way, the 2.5mm cable is in the ground..what size breaker do u use ?

I would not say its guaranteed or most likely to happen.

Real possibility of the 20A tripping.