Lighting spurs

[doodarr]

Hi guys,

Can any one tell me (incase I missed something) if this doesnt keep within 17th Regs.

I'm doing this to save on wire in my own home, not a customers. It's for lighting in the loft, 2 seperate rooms to be controlled by 1 switch as soon as you enter loft.

Taking 6A from CU in 1.5mm to 20A JB (for size & space) in the loft.

Using all 1.5mm from JB, obviously have switch but I want to take 2 lights (one to each room) from the JB using 2 seperate cables not loop in.

I then want to take 1 spur from each light so both rooms have 2 lights.

Please let me know if I'm missing anything obvious or if thats not clear or you need any other info.

Thanks

 

[telectrix]

forget the JB. use a small ad. box as a wiring centre. bring all cables in that and use wagos to connect.

 

[doodarr]

the rooms are abuot 12m span in total but the second light was only a few metres from the first which is why it was easier to spur.
Distance from JB & Switch if about (same in opposite directions) 3m to first light then 2m to spurred light and the same in the opposite direction. JB and switch are central

 

[JeanGenie]

If you wanted to save on a bit more cable, why not join into the upstairs lighting circuit rather than running a seperate feed all the way back to the board just for a few lights?

 

[MDJ]

Abandon the whole Idea and do it properly, ridiculous

 

[MDJ]

Just read the OP again, really stupid idea and I cannot see any reason for it, this way the cost will actually be more in cable IMHO than doing the job the right way and no joint box the right way, just madness, whats happening here??

 

[doodarr]

I didn't ask if you thought it was ridiculous or stupid. I asked if any one know if it is in violation of any of the regs. I didn't just dream it up I've looked at the cable location, where to be clipped so as not a tripping hazard. The switch wire will be about 8m in length as appose to 30cm. That’s where I'm saving the cable. The CU cable is about 1m and would be increased to about 9m. the lights go in opposite directions as the CU and switch are central.
The MCB is only turned on when I want to go into the loft, like when the central heating is getting reinstalled and we'll need to do all of the pipe work in there. (bungalow concrete floors).
The reason I didn't take from lighting circuit is all rooms have their own (or a max of 2 rooms) MCB's for lighting as do the sockets. This was I can isolate any room to do work, as I did last night and the Mrs. and kids didn't have any interference.
So i ask again, is it in any violation on 17th as I can't see any. Bad practice yes I understand but its rarely used and in my loft.
Thanks

 

[bigbaddave]

Surley this will take more time to install and then test... Wont it??

 

[doodarr]

Not really. Testing will be the same as I would have to test all points regardless. Installation wont be that much different either as the general run is the same only a shorter switch and CU length. Instead of going to end light go to JB and split it.

 

[Badged01]

Not the way I personally do it but in answer to your question it doesnt seem to contravene any regulation I can think of. You have a 'spiders web' radial circuit!. Just a question of ensuring your cable calcs etc .... support the installation method chosen!

 

[MDJ]

I still can't understand 2 things, (1) how it will save cable, and (2) so what if it means an extra 10 mtrs of cable is used, what's that in money 2 quid, probably the same price as your JB lol

 

[doodarr]

Checked all calcs against installation methods, lengths sizesa etc all fine.
Not the way I would do it for a customer but it will save me having 3 cable runs together on the same beam (CU SWitch & Loop) and save me about 16m in cable. It's only for my loft and will be tested and safe.

 

[doodarr]

MDJ,

The first in the lamp in the loop would be about 9m (probably longer) from the hatch (as its central), which is also where the switch has to be. I would have to run the switch and power to the first lamp (3 cables on a beam which also has others on takes more space and also cable. The way I am doing it means only 1 cable from JB and reduces the power and switch cable to under 2m for both. I know cost isn't a huge issue but its also space. All cales are clipped to avoid tripping over them. My original idea was the usual loop from lamp to lamp. Once I was in and looked at space and practicality this was the best idea. Seen 'Spider radials' but never used them and wasn't sure if 17th had brought anything to stop them being used.
I'm sure you all have have seen a job and thought, "why the hell have they done that......" then found out the reason why was practicality or lack of choice.