Downstream db

[Iona222]

I've got my 2391-52, but I've never tested a board downstream, its a db for an extension, there's no rcd on 1 lighting and 1 ring.
Is it ok just to change the mcb to a rcbo.

I remember wheni did the course they mentioned selectivity/discrimination

Regards

 

[telectrix]

is the feed to the sub RCD protected in the main DB?

 

[Iona222]

is the feed to the sub RCD protected in the main DB?

Ye. I could plug in my rcd tester see if it trips any on the main board. The main switch on the board is a rcd switch.

 

[timhoward]

The main switch on the board is a rcd switch.

Don't know which board you mean has rcd main switch, but surely in either case that means the lighting circuit and rfc are RCD protected after all?
Stick a photo of each board up if there is still confusion.

 

[Iona222]

Don't know which board you mean has rcd main switch, but surely in either case that means the lighting circuit and rfc are RCD protected after all?
Stick a photo of each board up if there is still confusion.

The main board has a rcd switch. Ye so I would say, they are protected.

 

[DPG]

As above, if the db is fed from a 30mA RCD then no point putting an RCBO in the db itself.

 

[DefyG]

The main board has a rcd switch

But this could be a RCD on a 'split' board and the downstream board could be from the non-RCD protected side in swa so wouldn't necessarily need RCD protection .......... Not enough info and pictures would be big help!