Mains Garden Lights

[maccers]

Hello! Just joined forum, after discovering not a great deal of advice generally available on this topic, I guess due to dangerous nature of it.

I am planning installing some bollard and spot lights in my garden. Since I have half the garden ripped up, I guess its a good time to install some power.

I have 100 m of 3 core armoured cable i intend to bury and run 3 spot lights (120 watt each) and aprox 8 bollard lights (60 watt each). These are all outside rated to IP 4/5, and the plastic junction boxes are 6/7 rated. I guess it depends to some extent on the DIY install as to how relevant these ratings really are....

I am planning to run them off existing power I have in the garage. This is where it gets interesting, the power to the garage is run off the mains that is present in the kitchen, this is itself protected by the RCD in the consumer unit. I know this as when I flip the RCD the kitchen and garage go out. Where the connection is made I am not sure, somewhere under the floor in the kitchen. All I know is it runs in from the outside on what looks like house wiring that would be used for a cooker (ie thick, rectangle) that is housed in plastic conduit from the garage, underground, then up the outside kitchen wall.

I am planing on bypassing where it currently runs off in the kitchen, and use some existing outside wire (the same type as described above) already plumbed in to the cupboard, and use a new RCD on the consumer unit for the garage power. The new connection will be outside the kitcen wall where the existing cable comes in, using one of the 6/7 rated boxes.

Questions:

1 - Will the new RCD for the garage need to be of a certain type for the load
2 - The the garage has a fuse box fitted, will this need an uprated fuse? (currently unsure whats in there at the moment)

Sorry if this post is long, I think I have captured everything though!
Cheers,
RM

 

[Spark123]

Providing your supply is TN/S or TN/CS, a 30mA RCD should be used to protect sockets reasonably expected to supply equipment outdoors. The current rating of the RCD contacts should be greater than that of the supply fuse to it. It sounds like you are wanting to scupper the existing arrangement and run a new swa cable out to the garage? Probably not a bad idea as it sounds like you have flat twin and earth installed in plastic conduit underground which I wouldn't consider good practice. The size of the supply to the garage depends on what you are wanting to use it for, i.e. a few lights and a lawnmower or a welder? The size of the SWA will depend on the size of the supply you need. The supply should be run directly from its own way in the fuse box, not coupled to the kitchen sockets especially if the kitchen sockets are part of a ring main. Please note this work is notifiable to LABC under part P of the building regs.