Types of rcbos

[Farmelectrics]

Just a quick question anyone no why some rcbos ie dorman smith have two trailing leads a neutral and also an earth when other rcbo just have one the neutral lead

 

[ElectroChem]

To my recollection, the earth is a functional earth that provides a current path to operate the electronic disconnector inside the RCBO even if there is a break in the neutral. This also results in sub 1MOhm IR results if the trailing earth is not disconnected prior to meggering the circuit.

 

[Farmelectrics]

Ok I understand that but why do some have them trailing earth leads and others dont

 

[ipf]

The functional earth is to increase sensitivity and hence, speed of operation.

 

[Farmelectrics]

Ok I understand that ipf but why do some manufactures have them and others don't you would of thought they'd make them standard ie all have them

 

[Richard Burns]

one assume that the flying earth lead is not required in the product standard but some manufacturers have assessed the level of risk of a lost neutral as being critical to the operation and addressed this. Other manufacturers have realised that if there is a lost neutral then there are far bigger problems than disconnecting an RCBO, which will have little effect, and have assessed the inconvenience of an additional cable outweighs the fractional advance that may provide a stability that is not required.

 

[davesparks]

There are two different standards to which RCBO's can be manufactured, one require the earth and one does not.
Neither is more sensitive or in any way better than the other