Branching/spurs and radial circuits

[Jim Ingram]

Hi,

Whilst I understand the logic regarding un-fused spurs and ring circuits, what is the position with regards to radial circuits. I have come accross various comments, such as sockets can only be added to the end of the circuit or simply that spurs are allowed.

Setting aside issues such as disconnection times etc, I can't see there is any (fundamental) problem with adding any number of sockets. There is no issue with overloading the cable, that one has with spurs from a ring.

I ask as my up stair lighting circuit splits into two branches at the first ceiling rose (3 more lights on one branch and two on another).

Thanks

Jim

[Andrew Gabriel]

Radial means the cable can branch out like tree branches, with sockets positioned anywhere on the cable.

Correct.

[Christian McArdle]

No problem at all. You may use any topology you like if the cable is rated to carry the full circuit load.

Christian.

[<me9]

Could you use a main 4mm² main radial, and connect a ring of 2.5 mm² to a single point on it, assuming earth loop impedences etc. are satisfied?

[Lurch]

On Tue, 04 Oct 2005 13:23:44 +0100, scrawled:

Sort of, theoretically, but not a recommended way of doing it. Why not just exend the 4mm radial?

[Christian McArdle]

Technically yes, if you can do the calculations to prove it. Not that you'd get it past inspection, though. A particularly useful version of this is the "lasso" circuit, which is a ring with the incoming at the end of a 6mm cable from the consumer unit. You have to do your own calculations, though. You can't rely on the tables in the On Site Guide.

Christian.