RCD on non-earthed supply

[JohnW2]

My error. I was thinking it was a a normal domestic tpye RCD and not an Active RCD.

To be fair, we don't actually know what sort of RCD it was/is ....

... For added safety I put an inline RCD in the cable between the socket and the bayonet plug ...

.. it is not impossible that he put a "normal domestic type (passive) RCD" in the the lead. However, the behaviour he is describing strongly suggests that it was an active one.

Kind Regards, John

 

[magicmushroom666]

Aye looking at that link it is indeed an active RCD

 

[JohnW2]

Aye looking at that link it is indeed an active RCD

Ah, thanks, I missed that link - that proves it, then!

Kind Regards, John

 

[Seb101]

Ah, thanks, I missed that link - that proves it, then!

Kind Regards, John

So is the logic that 'active' RCDs use/need the earth connection?

 

[bernardgreen]

So is the logic that 'active' RCDs use/need the earth connection?

Yes. if any one of the three conductors fail then the Active RCD will trip to ensure there is no hazardous voltage in the protected circuit and/or equipment.

 

[ban-all-sheds]

Yes. if any one of the three conductors fail then the Active RCD will trip to ensure there is no hazardous voltage in the protected circuit and/or equipment.

You can absolutely see the point of an inline RCD tripping if it detects loss of earth.

 

[JohnW2]

Yes. if any one of the three conductors fail then the Active RCD will trip to ensure there is no hazardous voltage in the protected circuit and/or equipment.

As I recently said, when I examined a number of sockets with active RCDs that was true of most, but not all, of them.

As I'm sure you know, being an 'active' RCD means, per se, only that it requires a live supply in order to remain 'set' (i.e. contacts closed). In the event of a power loss, the contacts 'open', and it cannot be reset unless/until power is restored. It seems that most manufacturers of them have added the requirement for an 'adequate' connection to earth, presumably for the reasons you suggest, but that is not a requirement, per se, of being and active RCD.

Kind Regards, John