Garden Light

[Graham Brooker]

My house is newly wired to the latest 17th Edition standard with RCBOs on every circuit. I want to install a garden light on a dusk to dawn sensor but do not want to run a separate 6A circuit from the consumer unit as I would damage the new laminate flooring. The easiest way is to run a 3A fused switched spur from the back of a power point on an external wall straight out into the garden using proper outdoor grade cable. Is this allowed for this type of lighting system?

Alternatively I could connect into the main lighting circuit in the toilet ceiling which would cause minimum damage to the new plaster that could be repaired.

Is it OK to spur from the mains power ring as long as you use a 3A fuse.

Thanks

Graham

[shazzbat]

AIUI you're not allowed to do this yourself unless you're part P registered, qualified or whatever.

Steve

[Andrew Gabriel]

Both schemes are OK.

My advice would be to make sure you have indoor double pole isolation for the outdoor circuit, so that if the outdoor circuit gets damaged or starts letting in water and tripping the RCD, you can isolate it from indoors without having to go out in the pouring rain to investigate or having to leave the whole circuit tripped. A fused switched connection unit will serve for this purpose.

One other thing to consider is what might happen if the outdoor part of the circuit caused the RCD/RCBO to trip whilst you're away on 2 weeks holiday (outdoor circuits tend to be much more susceptable to this than indoor ones). If the ring circuit trips, would your freezer thaw out, or your boiler and frost protection fail, or your tropical fish tank freeze? Loss of the lighting circuit might be less damaging. (This is why, where possible, it's a good idea to keep indoor and outdoor circuits separate, but it's not a regulatory requirement.)

[Graham Brooker]

Thanks for your advice. My boiler & freezer are on a separate ring main circuit but I can see the possibility of something else critical being plugged in at a later date. I will weigh up all the options and probably spur off the toilet lighting circuit with a double pole isolator switch.

At least you have put my mind at ease.

Thanks

Graham

[AJH]

To get round the Part P bit why not just connect the light by plugging it into a socket inside the house instead of using a spur (like you do a PIR floodlamp)? Freezers should be connected to the non RCD side of a split load board to avoid any inconvenient tripping problems, but if the plug you use for your outside light supply is an RCD type then it shouldn't affect the main circuits if there is a short outside. AJ

[ARWadsworth]

Freezers should be connected to the non RCD side of a split load board to avoid any inconvenient tripping problems, but if the plug you use for your outside light supply is an RCD type then it shouldn't affect the main circuits if there is a short outside. AJ

Under the 17th edition regs it is very likely that all the circuits require RCD protection.

There are installation methods that do not require an RCD but electricians seldom use them due to cost/time/profit.

Adam