RCD vs MCB...

[junksamiad]

Does an MCB protect against fault current in the same way as an RCD does? As in, both devices trip by way of detecting imbalance in the Line conductors and thus using magnetism to sprag the switch?

I ask, because if so, I can’t get my head round why an RCD is better than an MCB. I know that it is, and that an RCD detects low level leakage, but if so, what makes the MCB different in that it doesn’t detect low level leakage like an RCD does? Is there a difference in the device mechanics that restricts the amount of leakage an MCB will detect?

Help as always most appreciated.

 

[DPG]

No, an MCB protects against excessive current/short circuits, but an RCD protects against current flowing to earth.

 

[snowhead]

As in, both devices trip by way of detecting imbalance in the Line conductors and thus using magnetism to sprag the switch?

No only and RCD or RCBO do that.

MCB detects overcurrent
And an RCBO detects overcurrent and imbalance.

 

[cliffed]

No only and RCD or RCBO do that.

MCB detects overcurrent
And an RCBO detects overcurrent and imbalance.

& Earth fault protection

 

[Baddegg]

Think of it as....line and neutral touch mcb will trip...only line or only neutral broken rcd/rcbo will trip.....but invariably the rcd will also trip at the same time as the mcb on short circuit but once the damaged circuit is isolated the rcd (not rcbo) should reset....

 

[DPG]

& Earth fault protection

That's the imbalance bit that snowhead refers to.