Any idea what cable diameter I'd need to buy to run a 150w floodlight? I'll be running it around 20 - 25 metres around the side of the house. I'm assuming it woud be twin and earth I'd need to buy...

Thanks in advance

150w @ 230V is less than 1A.

A 5A cable should be more than fine, but if you're running it off a 13A plug, why not get 1.5mm 15A rated cable as it's not much more expensive and gives you loads of headroom should you wish to change to a brighter lamp in the future.

If your light fitting is not double insulated and requires an earth then I guess it would be twin and earth.

I used to use this stuff because it stayed flexible in the cold and wound up easily, but I'm not sure if your light is fixed or portable. Also we were using it for 1k or 2k lights hence the 1.5mm thickness.

Arctic Cable Blue 3183AG 1.5mm 100m - Screwfix.com, Where the Trade Buys

I would think it's pretty important to rate the cable higher than the fuse that is on the circuit you will be running it from.

Whatever you do make sure you comply with the regs and the cable is suitably protected. Also I would put a small loop in the cable and go into the lamp at the bottom, so any water on the wire will drip off below the light fitting and not make it's way in.

The cable size required, type of cable and fixing methods will all be in your 17th edition regs book (I am assuming you are a qualified electrician) as you should be to instal and test in outside locations

IEE Wiring Regulations 17th Edition : BS 7671: 2008: Amazon.co.uk: Institution of Engineering & Technology: Books

Thanks Cheezemonkhai - much appreciated!

If the light is attached to the house it doesn't 'come under Part P' and you can DIY.

Not sure on the suitability of normal T&E outside though - think you should do some more research - exterior grade conduit/armoured/exterior grade flex?

If the light is attached to the house it doesn't 'come under Part P' and you can DIY.

Not sure on the suitability of normal T&E outside though - think you should do some more research - exterior grade conduit/armoured/exterior grade flex?

Artic flex is IIRC designed for gold and outside. Regardless though, I'd never run a permant installation outside without conduit.

Might seem a stupid question ,but why run it round the outside .Isn't there a socket nearby in the house you can run a cable through wall to ? (And if doing that way ,don't forget to put in a drip loop where the cable enters building ).

Artic flex is IIRC designed for gold and outside. Regardless though, I'd never run a permant installation outside without conduit.

UV is your enemy cheeseboy.

If the light is attached to the house it doesn't 'come under Part P' and you can DIY.

Not sure on the suitability of normal T&E outside though - think you should do some more research - exterior grade conduit/armoured/exterior grade flex?

Thanks Kandy - wasn't sure on regulations. It's attached to the house so should be fine.

UV is your enemy cheeseboy.

Surly the UV stabilised artic flex in conduit would be ok or am I missing something blindingly obvious or more subtle here.

Either way, I'm not a leccy so