Lighting radial circits

[JohnW]

I am erecting a shed/garden office with electrics to be fed with SWA cable to a RCD fitted shed consumer unit with two mcbs. I have an electrician booked to do the Part P certification. The lighting mcb was originally planned to feed a single switch which would then feed two internal lights. I am going to do the wiring, with the sparks doing the terminating and certification. I cannot contact the sparks before I need to put up plasterboard over the cabling, and now want to add an external light separately switched. Is it permissible to run a second radial circuit to the second switch straight from the mcb, or can I only have a single wire from the mcb and therefore have to fit a junction box away from the consumer unit to feed both circuits.

Many Thanks

John

[Owain]

On a radial circuit you can run as many wires from the MCB as can safely be acommodated by the terminal. Two should be no problem.

Owain

[Andrew Gabriel]

Multiple wires are fine, providing they fit in the MCB terminals properly, which won't be a problem with lighting circuit wire.

[David Hansen]

On 4 Jul 2006 11:55:55 -0700 someone who may be "JohnW" wrote this:-

Yes.

However, it is often easier to just have one, though this depends on the layout.

Is the external light to be switched from outside as well as inside? If so the easiest way of doing this will usually be to install a double two-way switch, just inside the door, fed by a single core, controlling both lights. From this three cores, plus an earth, go to the outside switch, so the outside light can be switched from either switch.

Locators are useful on all switches where one might be trying to find them in the dark, such as halls and switches for turning on the first light inside a building.

[Dave Plowman (News)]

Yup - that's fine. Provided the MCB is rated to protect the lowest rating of either cable - which in practice with a lighting circuit it nearly always will be.

[tinnews]

Not possible, he can 'self certify' if he does all the electrical work but he can't provide a certificate for work he hasn't done. You need to notify the Building Regs people at the council to do it properly.