Outside light wiring advice

[jimbob1jimbob]

I have a situation where there there is existing wiring for an outside porch light, but I do not understand how the wires connect.

There are 3 red wires, 1 black wire, and 2 green/yellow wires coming out of the wall, but only 1 brown, 1 blue, and 1 green/yellow to connect to on the light. unfortunately there are no instructions for the light, and as I cannot see how any previous light was connected, I am puzzled as to whether all the red wires connect together or not.

Any help would be appreciated.

Thanks

 

[BenStiller]

do you have a switch for these existing wires?

 

[HDRW]

Can you see how the wires are sheathed together, or is that lost in the wall?

My guess would be that you have a T&E cable coming from a supply somewhere (possibly another light), and that's the black, one red, one green/yellow, then another T&E coming from the switch, being the other two reds and the other green/yellow.

If so, you need to identify which red is the live and which two go to the switch.

Easiest (safest!) way is to switch off the power, turn on the light switch and do a continuity check between each red and the others - mark them 1, 2 and 3 somehow, then check 1-2, 2-3, 3-1.

One of those pairs should show a short between them, and those are the ones that go to the switch. Final confirmation is that turning the switch off removes the short. If you're not sure of the switch position, try it both ways!

If there is no short under any circumstances, or it doesn't go away when you turn the switch off, then my guess was wrong...

Cheers,

Howard

 

[jimbob1jimbob]

There is a switch in place (inside the house, but wired through the internal walls somewhere).

In ref to the comment by HDRW, the wiring is exactly as you guessed. I'll try the potential solution you suggested.

Thanks for the help.

J

 

[HDRW]

There is a switch in place (inside the house, but wired through the internal walls somewhere).

In ref to the comment by HDRW, the wiring is exactly as you guessed. I'll try the potential solution you suggested.

Thanks for the help.

J

Errr - I didn't actually suggest a solution, just an investigation!

This is the solution... You'll need to connect:
the black to the blue
both green/yellows to the green/yellow
one of the switch-reds to the brown

That's the easy bit - you finally need to connect the live red to the other switch-red, but to nothing else!

One way to do this: if you can fit a choc-box:

behind the light fitting, put the last two reds into a choc-block, connecting them together, then put the choc-block into the choc-box and you're done, however it needs a lot of space!

Others will doubltless suggest other methods...

Cheers,

Howard

 

[jimbob1jimbob]

Dear Howard
I now realise that you indeed had not suggested the solution!!
I have tested the Reds and you are correct in that Reds 1&3 both make a circuit when the power is off (no other combination makes a circuit at all).

If I understand your solution correct then:
Black (out of the wall) connects to Blue on the light fitting
Grn/Yel x 2 (both from the wall) connect to the Grn/Yel on the light fitting
Red 1 or 3 (out of the wall) connect to the Brown on the light
The remaining 2 Reds out of the wall connect together in a terminal block.

Many thanks

Jim

 

[HDRW]

I have tested the Reds and you are correct in that Reds 1&3 both make a circuit when the power is off (no other combination makes a circuit at all).

Did you confirm that the 1-3 circuit was broken by turning off the switch? (Just to exclude any other possible wiring scheme)

If I understand your solution correct then:
Black (out of the wall) connects to Blue on the light fitting
Grn/Yel x 2 (both from the wall) connect to the Grn/Yel on the light fitting
Red 1 or 3 (out of the wall) connect to the Brown on the light
The remaining 2 Reds out of the wall connect together in a terminal block.

Yup, spot on! I don't suppose the light fitting has a spare insulated terminal that you could use? That would make it too easy, and would cost the manufacturers an extra 5p to include...

Cheers,

Howard