Is this ok to do ?

[daytona]

sorry mate,it did turn into a bit of banter between the sparks on here

the way to do this is to find the last light on the circuit and come from there.run the cable through your spur and off to your new lights.that way all you did was extend the circuit to outside.

right, the rcd debate.you do not need rcd protection for lights outside.some people on here say its not a bad idea to have an rcd and this is probably confusing you.the reason some are saying this is you need to take into account the type of lights/location/cable used.i feel the point bernard green was trying to make(excellent post as always)is that you have extended a circuit outside the equipotential zone(your house)and if there is likely to be any possibility of impact damage,for example if you had a ladder on your shoulder and you were not beingcareful taking it down the alley,could you smash it through a fitting you could possibly be killed.then rcd protection would be a good idea as it would minimise the risk.

in short you need to weigh up the risks and type of installation,but in general doing as per my fist paragraph is the safe and correct way to do it based on the info we have on your installation

 

[daytona]

first ,first why do i keep writing fist.i think my keyboard needs cleaning

 

[daytona]

one more thing we have all forgotten,i dont know how you are going to get the cables from fitting to fitting.if you intend to clip twin and earth direct,then this is against regs as its a thermoplastic cable.you have to use thermosetting as in butyl minimum.

 

[garrymum]

one more thing we have all forgotten,i dont know how you are going to get the cables from fitting to fitting.if you intend to clip twin and earth direct,then this is against regs as its a thermoplastic cable.you have to use thermosetting as in butyl minimum.

All the twin and earth will be in the loft. No twin and earth will be visible from the outside.

Thanks for all your help on this. What is the difference in taking the feed from the last ceiling rose in the chain and feeding two lights from that. And, my proposed method of adding a spur from the already installed JB (which has a feed to 1 other 150w light), taking this spur to another JB, which in turn feeds two more lights.

Is it that my option is not safe or it is safe, but is not the normal method a sparkie would do it?

Is the last ceiling rose on the chain the one with only 1 set of wires?

If I just wire a spur from a ceiling rose won't that spur only become live when that light is switched on?

 

[mdbalson]

The last rose on the circuit will have two T+Es coming into it, the feed cable & the switch drop cable.

The above is if your lighting circuit is wired as in the 1st method in the picture

Or your lighting circuit may be wired as in the 2nd method in the picture

http://i167.photobucket.com/albums/u125/mdbalson/electricslightingceilingroses2qsf.jpg

 

[Observer]

one more thing we have all forgotten,i dont know how you are going to get the cables from fitting to fitting.if you intend to clip twin and earth direct,then this is against regs as its a thermoplastic cable.you have to use thermosetting as in butyl minimum.

All the twin and earth will be in the loft. No twin and earth will be visible from the outside.

Thanks for all your help on this. What is the difference in taking the feed from the last ceiling rose in the chain and feeding two lights from that. And, my proposed method of adding a spur from the already installed JB (which has a feed to 1 other 150w light), taking this spur to another JB, which in turn feeds two more lights.

Is it that my option is not safe or it is safe, but is not the normal method a sparkie would do it?

Is the last ceiling rose on the chain the one with only 1 set of wires?

If I just wire a spur from a ceiling rose won't that spur only become live when that light is switched on?

The pros are being really helpful on this one, aren't they (not).

As a humble and of course wholly inadequate DIYer, I'd suggest there is nothing wrong in doing as you suggest except it's a wee bit messy. A lightng circuit is usually a radial. Adding one 'spur' or branch is electrically safe and adding a second branch from the first one is also electrically safe because all of the circuit is still protected by the fuse/MCB at the CU. However, it is 'tidier', if feasible, to have a single radial without branches. That way it makes it easier for someone coming after you to work out how the circuit is configured.

The last ceiling rose on the existing spur will have two cables if you have 'loop in' at light and one cable if you have 'loop in' at switch.

If you have the latter, then you would need take a permanent live and neutral from the switch because the live at the rose will be a switched live (and have the drawback you describe). If your lights are wired 'loop in' at rose, there will be a permanent live (and neutral) there and a switch drop cable as describedby mdbalson.