RCBO v. mini-RCBO

I think the first generation RCBOs were taller, then they managed to shrink them to MCB size in second generation, so I don't think there's any 'point' as such to the tall ones.

The small ones often do not have the functional earth fly lead.

Looking at the manufacturer's site for Wylex and Crabtree, neither do the big ones. The full-size ones mention disconnection before testing the circuit; the miniature ones don't.

No RCD/RCBO has a 'functional earth fly lead'.

The white lead here ...

...is not part of the trip function. No idea what its for, perhaps to earth something in the switch...

It allows the RCBO to continue working and detect a LE fault in the unlikely event of a missing/lost neutral.

RCD's do not have these fly leads.

And wankers oversleeve the flyleads with green/yellow. But then some RCBO manufactures have a flylead with a green/yellow cable.

Zoom in ... it's shown as part of the circuitry measuring current differences

It is - but it adds a capability that normal RCDs don't have.

It will allow it to trip in the unlikely event that you get a neutral disconnection. (which on a PME supply could leave all earthed metalwork in the house at mains voltage)

Can that fly lead have a DIY equivalent wired into a mini-RCBO? I can't see from the image that Andy posted what it's connected to on the RCBO.

No. (It'd have to be connected internally to the imbalance detection circuit).

Glad you came along Adam!

Bill

You haven't looked at the circuit diagram have you? Or thought about what you just said.

How is the current - the massive current - that should flow down the neutral going to get back to base if there is no neutral?

Down that poxy little wire to *earth*? What???? Earth is simply safety, it never passes significant current except under fault conditions. You cant operate *at all* without a neutral.

I did and its clearly there to earth a bit of metal in there.

THINK. How COULD it be part of it. If it passes any current at all it is CREATING an earth fault.

I see - thanks.

All they have to do is draw the current for the electronics *before* the imbalance detector.

WHAT electronics?

THESE electronics ... the white earth flylead seems to connect to a pin on the balance transformer (whatever the correct term might be)

no, it might only go to the other circuitry on the PCB, not to the windings ...