We have a small brick built tack-room and two loose boxes which have
mains power fed to them from a 20 Amp RCBO in the garage consumer
unit.

The feed comes into (another) small CU on the wall in the tack room,
this currently has a main switch and three MCBs feeding sockets and
lights.

Is there actually a requirement for the sub-CU in the tack room to
have a 'main switch' that turns off all the circuits in the tack room?
I'd like to replace it (the small CU that is) with an even smaller one
that only has space for 3 MCBs, quite sufficient if there doesn't have
to be a main switch.

--
Chris Green
·

On 18/06/2020 13:15, Chris Green wrote:

We have a small brick built tack-room and two loose boxes which have
mains power fed to them from a 20 Amp RCBO in the garage consumer
unit.

The feed comes into (another) small CU on the wall in the tack room,
this currently has a main switch and three MCBs feeding sockets and
lights.

Is there actually a requirement for the sub-CU in the tack room to
have a 'main switch' that turns off all the circuits in the tack room?
I'd like to replace it (the small CU that is) with an even smaller one
that only has space for 3 MCBs, quite sufficient if there doesn't have
to be a main switch.

It would meet the requirement of protecting the smaller capacity cables
as they transition from the submain. So it becomes just a MCB enclosure
rather than a Consumer Unit as such.

I can't immediately think of a regulatory requirement that it has its
own isolation, although personally, I think it would be better design to
have a switch there in case someone unfamiliar with the installation
should need to isolate in an emergency or at the very least, a label
indication where the nearest point of isolation is.



--
Cheers,

John.

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On 18/06/2020 13:15, Chris Green wrote:
We have a small brick built tack-room and two loose boxes which have
mains power fed to them from a 20 Amp RCBO in the garage consumer
unit.

The feed comes into (another) small CU on the wall in the tack room,
this currently has a main switch and three MCBs feeding sockets and
lights.

Is there actually a requirement for the sub-CU in the tack room to
have a 'main switch' that turns off all the circuits in the tack room?
I'd like to replace it (the small CU that is) with an even smaller one
that only has space for 3 MCBs, quite sufficient if there doesn't have
to be a main switch.


A question like that can start electricians arguing.

But I am a firm believer that the main switch on the supply DB to the
sub DB meets all the requirements for isolation.



--
Adam