3 Way Wiring Explaination.

[leighm]

Hi,

I'm adding a couple of wall lights and need 3 switches to operate them from 3 locations (bottom of satirs (1), top of stairs (2) and end of landing (3)). I have a spare 16amp MCB in my CU and my wall isn't boarded yet so access isn't an issue.

I have all the necessary equipment as per this illustration: http://www.diydoctor.org.uk/projects/23wayswitches.jpg but i don't know how to then connect this circuit to the new lights.

I'm assuming that the top switch in the diagram marked circuit cable is the feed to the CU, but where do the lights fit into all this?

No i'm not an electician and yes i'm aware of the regs but i want to do it myself.

Thanks in advance,
Leigh

 

[Steve]

the "circuit cable" goes up to the junction box just like a normal switch cable. That cable is a live and a switched live.

 

[leighm]

Sorry crafty, 'like a normal switch cable' doesn't really help me as this is the first time i've attempted anything like this.

I have all my switches wired up as per the diagram, i have my lamps on the wall, but i'm unsure how to connect the switches to the lamps and the lamps to the CU.

Should i take all 3 lamps to a junction box?

I suppose what i'm after is a 'numpties step by step guide', as until i've wired everything up, i can't insulate/board my wall.

Any help would be appreciated.

Leigh.

 

[RF Lighting]

Does this make it any clearer? I found it in the FAQ

The L & N wires connect to your fuse box
Please note there are no earth wires shown in these diagrams for clarity, but you must take an earth to every switch and light. Also the 16A MCB in you CU should be replaced with a 6A MCB.

 

[RMS]

Think this might confuse the guy even more as the diagram illistrates two different ways of wiring 2way and intermediate switching.

lieghm, what if we tell you the wires to run and then when your ready to connect up you can returen to the forum for this? or will you be doing the connections straight away?

RMS

 

[Steve]

RF, could you do that in harmonised colours please?


only joking

 

[RF Lighting]

Just you behave, Mr Crafty

 

[leighm]

RMS, you're spot on there, confused am i lol. Especially trying to visualise the diagram in reality.

the easiest thing for me to understand would be to work in terms of wires, and where they go to/from the lamps, switches and CU.

I just don't seem to be able to get all this around my head.

Thanks in advance,
Leigh.

 

[Steve]

I just don't seem to be able to get all this around my head.

ah, well, you're going about it the wrong way! You need to get your HEAD around the PROBLEM!

sorry im in a funny mood today lol.

Look at the colour diagram RF showed you. And imagine 3 core and earth strung between the 3 switches (so theres 2 runs) and the yellow is joined at the second switch.

At the first switch, there are 2 wires into each of L1 and L2.

Ignore the picture of the lamp and then those 2 wires labelled L and SWL go to the ceiling rose/junction box.

There are several pictures of junction boxes in "for reference"

 

[securespark]

Basically all it is is a 1 way light switch converted to two way using 3C & E cable, if you want further switches (I have done a 12-way myself on a huge corridor), just cut into the 3 core and add intermediate switches. Connect L1 & L2 to the switches and "through" the common.

But I'm afraid if you are struggling to grasp the principle with all you have here, maybe you should employ someone who is familiar with this scenario.

 

[leighm]

Ah=ha, now we're talking, by thinking of it as a simple single switch its becoming clearer.

I think my main problem is the terminology which to you guys is second nature, but for me doesn't mean a thing. I build databases for a living so if i speak to people about entities, they look at me blank... if i say table instead, they have a better idea about what i mean... however i'll admit that nobody ever died from building a database incorrectly.

Anyway, back to the wiring... I found this in the FAQ section which clears things up a load: http://img524.imageshack.us/my.php?image=jb3vr.gif
as its what i see as non abstract, unlike a wiring diagram.

My only questions now are:

1. the JB i have only has 3 connection points, not 4. Are 4 point ones easily available?

2. On the diagram of the switches, the circuit cable connects to L1/L2 where as on the above diagram, it goes to L1/C... should i do exactly the same, but wire the switch to L1/L2?

3. The 'Supply to Next Light' on the diagram is clear, but as i have 3 lamps, do i need an additional JB or wire Lamp 3 to the same points as lamp 2?

Other than that i think i've cracked it.

Thanks for everything so far, i'm 90% there.

Cheers,
Leigh

 

[ban-all-sheds]

nobody ever died from building a database incorrectly.

Check comp.risks, or subscribe to the Risks Digest - I think you'll find they have....

 

[leighm]

LOL, like it sheds... i was thinking more about their operation, but indirectly they could obviouisly be quite lethal depending on the data stored.

Cheers,
Leigh.

 

[Steve]

1. the JB i have only has 3 connection points, not 4. Are 4 point ones easily available? yes. go to a DIY shed and you will see they have a vast range of junction boxes in various sizes and terminal capacities.

2. On the diagram of the switches, the circuit cable connects to L1/L2 where as on the above diagram, it goes to L1/C... should i do exactly the same, but wire the switch to L1/L2? If you are having 2 or 3 or, as secure spark said, 12 switches, then connect it as shown in the switches diagram, to L1 and L2, but if you're only using one switch, this wont work, and you should connect to L1 and COM.

3. The 'Supply to Next Light' on the diagram is clear, but as i have 3 lamps, do i need an additional JB or wire Lamp 3 to the same points as lamp 2? No, the wire that feeds the lamp in the diagram, just loop that to the 3 lights (i think you wanted them all switched together?)

Other than that i think i've cracked it.

Thanks for everything so far, i'm 90% there. You're welcome

Cheers,
Leigh

By the way, secure, where did you do that 12-way switch circuit?

 

[leighm]

Crafty, thank you so much, thats cleared it all up.

So, just to confirm what i need to do (This way i get it straight in my head and you guys have an opportunity to correct me before my unwanted new hair do...)

1. Wire switches as per http://www.diydoctor.org.uk/projects/23wayswitches.jpg

2. Run supply to JB

3. Wire switch 1 as per http://img524.imageshack.us/my.php?image=jb3vr.gif but to L1/L2, not C

4. Connect remianing 2 lamps to lamp 1 (L to L, N to N, E to E) - Please confirm if i have to come back to the JB from the last lamp or not.

5. Get girlfriend to try the lamps whilst i stand in the garden in a pair of wellies.


Thanks again guys for your advice and patience

Cheers,
Leigh