Difference between Single and Double pole MCB

[thebigbadpad]

Hello guys
Just wondering what is the real difference between a single pole MCB and a double pole MCB.
i dont understand why you would need both live and neutral to trip in a double pole becasue in a single pole if live trips then neutral wont be live anyway.

Any Help Much Appreciated

Thanks Guys

BIGBADPAD

 

[ricicle]

In a system where none of the outputs from the secondary of a transformer are earthed then both poles need isolation/protection as there will be a PD between either pole and earth.
Centre tapped secondaries also need DP isolation/protection.
Using a MCB on an unearthed DC supply will require two pole protection/isolation.
In an ideal world TT supplies should have DP circuit protection as there can be a PD between N and E. Even other systems would benefit from DP protection/isolation.

 

[Taylortwocities]

Neutral is considered a live conductor.

Fully disconnecting a circuit is very necessary in TT installations, for instance where neutral usually nowhere near earth.

Have a read of the BGB 537.1 for clarification.