Two way switched spot light bar

[ivor383]

Well, I've been through all the posts and the FAQs and I can't find this one!

I've just replaced a hanging light with a spotlight bar and all I have coming out of the ceiling is two twin and earth cables (the old style red, black and bare earth).

But, like a twit, I didn't make a note of the wiring (it's two way switched and there is no extra switched wire coming through the ceiling) it used to work perfectly and now I either blow a fuse or have the spot lights on all the time!

I'm sure the two reds were joined with a choc block, as were the earths, so I think the black's to blame.

Can anyone give me some guidance on how to wire it correctly?

 

[Albert]

If you are sure that there are no other cables, you should identify the supply cable, it will be the live (red) one when the fuse (MCB) is on (when the two cables are separated) the other red will be dead.
I suspect that the other is a live switch, this means that the red will be connected to the supply live (red) and the black to the live of the light, the blue of the light to the (black) of the supply. Please be careful because my advice could be wrong if I did not understand your post. BTW the earth wires have to be insulated and the switch live has to be marked with a brown/red sleeve/tape.

 

[ivor383]

Thanks Albert, I'm pretty sure I can identify the power from the MCB (I'll be extra careful!)

There may be some people on the board that have seen this configuration before, so I'll hold fire until tomorrow morning...then give it a try.

I have a feling I may be going through some more fuse wire...

 

[JohnD]

read the first two

//www.diynot.com/forums/viewforum.php?f=8

 

[RF Lighting]

//www.diynot.com/wiki/electrics:blackswlive

Notes,
(If you only have 2 cables ignore the supply to next light cable).

 

[ivor383]

Thanks for the replies peeps!

I'll have a good read up in the morning and see if I can come up with a sensible solution and post the results.

 

[ivor383]

Well, it's getting confusing now.

I've printed off the wiring diagram, but that's only for single switching, so it doesn't really help, unless I'm being a complete idiot

Both blacks at the ceiling fitting lead to the two separate switches that's for sure.

If I connect one of my meter leads to one of the blacks at the light and the other meter lead to the black on the switch, it shows a connection and it will switch on and off, but when I go to the second switch, it shows the the black at the light is connected, but switching doesn't effect the meter reading, the needle remains all the way over.

If I connect the meter to the other black cable at the light, i get exactly the same result at the switches, but vice versa, in other words the other switch is switchable and the first switch doesn't effect the needle, it remains hard over showing a continuous connection when you operate it.

Does that make sense?

I can't put a red sleeve on one of the blacks because they are both switched!

Anyone got any ideas?

 

[ivor383]

Got it!

Thanks again for all your help. I re-drew the wiring diagram for two way switching so the reds were joined with a connection block leaving two switched blacks, which I connected the brown and the blue on the spot light bar.

Works a treat! Thanks again.

 

[Steve]

I dont think you fully understand it, but you've wired it right anyway.