Several sockets and lights on a spur?

[mike42]

Hello All

2.5mm ring is protected by a 32a rcbo in the main consumer unit.

I'm thinking about using a short length of 4mm to spur from a socket into the garage which is on the other side of the wall. This would feed a small "garage" consumer unit with a (I think pointless from a protection point of view) 40a or 63a main breaker switch. From there would be a single 2.5mm radial on a 16a mcb and another 1.5mm radial lighting on a 6a mcb.

Is that allowed or does the whole lot need to be on a 13a fused spur or does it all need to come direct from the main consumer unit ?

 

[securespark]

The 40 or 63A "main breaker switch" is just a double pole switch offering no protection at all.

 

[mike42]

But is such a spur allowed ?

 

[SUNRAY]

Electrically and regs wise there is nothing to stop you putting a consumer unit on a ring, it does offer an advantage of total isolation of the garage if required. I would suggest using nothing bigger than 16A MCB's or RCBO's.
It would be nicerer to extend the ring to the new CU with 2 cables to match the existing ring rather than use a 4mm² spur.

 

[EFLImpudence]

It would be nicerer to extend the ring to the new CU with 2 cables to match the existing ring rather than use a 4mm² spur.

I disagree - totally pointless.

 

[blup]

Extend the ring and you have options to break into it again later if the need arises.

 

[EFLImpudence]

Extend the ring and you have options to break into it again later if the need arises.

So why can you not do that with a 4mm² spur (or radial)?

There is no point having a ring circuit with both legs in the same place.

 

[EFLImpudence]

But is such a spur allowed ?

2.5mm ring is protected by a 32a rcbo in the main consumer unit.

I'm thinking about using a short length of 4mm to spur from a socket into the garage which is on the other side of the wall. This would feed a small "garage" consumer unit with a (I think pointless from a protection point of view) 40a or 63a main breaker switch. From there would be a single 2.5mm radial on a 16a mcb and another 1.5mm radial lighting on a 6a mcb.

Is that allowed or does the whole lot need to be on a 13a fused spur or does it all need to come direct from the main consumer unit ?

If you use 4mm² for the whole spur no fusing is necessary and you can have many sockets.

 

[Ragnar_AT]

Either way you could run the sockets straight off of your new connection and the lights off an FCU with a 5 A fuse.