CU - RCDs as the main switch?

[steamboatwilly]

Can a (eg, MK BS4293 63A 30mA) RCD be used as a main switch in a CU if it's the ONLY source of switching for that CU? I'm about to start work on a CU with RCD-Breaker-Breaker-Breaker-etc-Main Switch-Breaker-Breaker-Breaker-etc.

I obviously need to add a new RCD for the second split but would the board then need a main switch for the whole thing? These boards used to have labels saying something like "All switches must be off to disconnect from the supply".

...wondering...

 

[Phil Mumford]

All installations should have a single point of isolation. One RCD switching the second can be done but you need to have some discrimination (possibly a time delay RCD).

As you are undoubtedly aware the partially compliant 17th edition boards have a main switch that feed both RCD's.

A cheap way out would be to have a DP 100A switch in a 2 way enclosure and use it to feed both RCD's? Mark it up as main switch and everyone is happy !

 

[steamboatwilly]

All installations should have a single point of isolation. One RCD switching the second can be done but you need to have some discrimination (possibly a time delay RCD).

As you are undoubtedly aware the partially compliant 17th edition boards have a main switch that feed both RCD's.

A cheap way out would be to have a DP 100A switch in a 2 way enclosure and use it to feed both RCD's? Mark it up as main switch and everyone is happy !

Thanks Phil....there is a 100A Hager 2-pole switch on the tails so we're hunky-dory there. I've not had the covers off the CUs (there are 2) so I'll need to check if they share any common bars inside. The board here is undoubtedly 16th Edition.....I need to take a peek inside tomorrow.