Is an FCU needed for lighting from a 16A RCBO?

[endecotp]

Dear Experts,

I have a simple radial circuit for an outside socket fed from its own 16A RCBO. It uses 2.5mm^2 cable.

I’d like to also run the outside lights from this circuit, rather than the house lighting circuit. The lights are wired with 1 or 1.5 mm^2 cable.

Do I need a 3A FCU?

I would have said yes, to protect the thin cable in the event of a fault, but I recall some rules about some devices being assumed to draw no more than their rated current, or something. Can anyone explain?

Thanks.

 

[EFLImpudence]

1mm² T&E is rated at 16A - if clipped or buried in masonry.

That should answer your question.

 

[endecotp]

Thanks, that’s nice and easy!