# Forum Home Renovation Lighting  Simple lighting wiring

## dutchroll

So the big shed wiring continues. Please be advised that this has all been done in conjunction with my long-term sparky. None of these circuits are currently live, nor are any terminations done anywhere (that's his job). He will be inspecting wiring installation progress later next week, and trusts me to correctly do conduit, cable tray runs, enclosures, etc  IAW the standards which we've talked about in depth. Most of the power cables are done, labelled, & hanging out where they're supposed to be. Looks pretty neat, if I do say so.  :Biggrin:  
We did chat today about lighting & my light plans are pretty simple though I've since managed to muddle my thoughts a little here & he's decided he wants the long weekend off with the family (how dare he, when I'm pulling cable?  :Biggrin: ). There won't be any dual switching. Just a 3 gang switch, and 3 lots of 2 twin fluoros. Ie, each switch will control a pair of twin fluoros. There'll be a similar but much smaller outside light circuit too. 
I'm pretty certain he said simply run a single 1.5mm 3 core cable (I have a whole new reel of it) from the main switchboard to the switch location, then same again from the switch location to the first light to be controlled by that switch, then same again from that light to its twin on the other side. I _think_ he said then a single 1.5mm 3-core from that 2nd light to the 1st light in the _second_ pair and so on. Each light takes a 3 core cable from the previous one. Does that sound right? That is, there is no need to run 3 lots of 1.5mm 3-core cable from the 3-gang switch enclosure, as some sort of "sparky magic" at the switch and subsequent light fittings sorts out which pairs are on which switch. He did mention looping at the light, not at the switch. 
I don't need to know how the terminals will all be connected. His problem. Just that I have the 3-core cable running to the correct bits. 
Or am I so far off track that I need to interrupt his holiday weekend?  :Eek:

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## Random Username

Unfortunately, there's no sparky magic that will let you control three pairs of lights independently with three switches but using only a single run of twin-and-earth.  
Even looping requires taking an active/switched active to a switch for control purposes. 
Wire is cheap. What I'd do (even though I'm not a sparky) is simply run three lengths of 1.5mm T&E - one from each light pair location back to the switch.  Switchboard|
               |------> Switch ---> first light 1 ---> first light 2
              |
              |------> Switch ---> second light 1 ---> second light 2
              |
              |------> Switch ---> third light 1 ---> third light 2
              |             Other light you mentioned??  The other way would be: 
Switchboard |
               |---------> first light 1 ---> first light 2 --->second light 1 ---> second light 2 ---> third light 1 ---> third light 2 ................|................................|........................................|
   Switch <--------|................................|........................................| .................................................|........................................|
   Switch <------------------------------------------........................................|  ..................................................  .......................................|
   Switch <-----------------------------------------------------------------------------------   
Also see here: http://www.goo.gl/9d33T  (PDF file)

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## chalkyt

Both of Random Usernames diagrams will work. In the top diagram, all cables are twin+ earth (which you already have). In this case, the neutrals are all connected at the switching point and the actives connected to each switch. Your electrician possibly wouldn't do it this way if he was trying to minimise the cable cost as you are running extra neutrals and earths that you pay for but don't need compared with diagram 2. However as you have the cable, you might as well use it and there is no technical problem with doing it this way. 
What your electrician was talking about is probably something like diagram 2. In this case, an ANE (twin+earth) is supplied to each pair of lights. Normally this arrangement would be ANE from the switchboard to Light 1 then to Light2, then from Light 1 to Light 3 then to Light 4, then from Light 3 to Light 5 then to Light 6 as below. Then run a twin only Active+Switch Wire from each of Light 1, 3, 5 back to the switches (i.e. this is called looping at the lights as the connections are all done within the light fittings)  
This version of diagram 2 would look something like...  
Swboard |----------->--------------------------------->--------------------------------->
First light 1 ---> first light 2      second light 3 ---> second light 4      third light 5---> third light 6 ............|............................... .|.................................|
Switch <---- ............................... .|.................................| ............................................ .|.................................|
Switch <------------------------------------- ..................................| .............................................. .................................|
Switch <------------------------------------------------------------------------   If you only plan on running a single switch wire from each pair of lights back to the switches, then you will either need to run one of them as a twin in order to get an active supply to the switches or run a separate single Active from the switchboard to the switches. This is an unusual way to do it, so I imagine that you either  misunderstood your electrician or he has something in mind that he didn't talk about to you (unlikely). 
The diagram 2 version is a bit more complex and the right wires do have to be in the right places. However, it is your shed and sometimes the way cables are run is determined by the distance between the switchboard, switches and lights if you want to minimise cable costs. 
My inclination would be to go with the diagram 1 version if you want to continue with your productive weekend, since you seem to have plenty of cable and at about $1 per metre you can afford to waste a bit. But "you pays your money and makes your choices,'  Good luck! 
Read more: http://www.renovateforum.com/newrepl...#ixzz27uHt7lXu

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## dutchroll

Ah yeah OK, as I thought about it further after making the post, I thought "nah, a single 2C+E from the 3-gang switch to the light just doesn't make sense". It was pretty crap mobile reception when we were chatting, and clearly I misunderstood what he was saying. He definitely said "we'll loop at the lights", so I got that bit right! 
Anyway, today I ran out of 25mm corro, 25mm fittings and 1/2 saddles, and the 100m reel of 4mm cable for the power circuits ran dry too & the wholesaler is closed tomorrow. Still, there are quite a few GPO enclosures to fix to various spots, and I need to bang the 25mm earth stake in. Plenty to keep me busy. 
I'll bother him again on Tues to confirm which method he wanted & get it sorted before I run the 1.5mm 2C+E cables across the roof. I really don't want him turning up in a week and shaking his head and frowning!  :No:  Thanks guys!

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## dutchroll

> Both of Random Usernames diagrams will work.

   Just chatted to my sparky & got it sorted. 
One 2c+e 1.5mm cable per switch, each running to the first light controlled by that switch. Then he loops to the second light in the pair from there. So the 3 gang light switch will have 1 x cable running into it from the board, and 3 x cables running out from it up the cable tray to the shed roof purlins. Now I'm happy. That makes eminent sense. He reckons those 3 cables can all run in the same 25mm conduit too, where necessary. 
Dunno how I managed to cock that understanding up!  :Confused:

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## chalkyt

All good. What he wanted was the Dwg 1 version by the sound of it, anyway.

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