Dead short?

[laferret]

I'm trying to install an outside light at my front door. I've fitted a 2 gang switch in place of the single and run a twin & E into it following the same path as the other wiring for the internal lights for the stairs. I opted to connect using a junction box as it is close by and the original wiring was identifiable as the lighting loop and switch feed for my lounge.

In my first attempt to connect it all the outside light and inside light strobed together. Realising the wrong cable was chosen I opted for the identical cable running right next to it under my floor boards. Attempt two resulted in the outside light only working when the lounge light is on.

Wiring into the ceiling rose isn't really an option as it means pulling up undisturbed floor boards.
My house wires are black and red to add to the fun.

Was attempt 1 a dead short and attempt 2 wired to the switched live?
Do i need to go back to JB 1 and swap my wires over?

Many thanks

 

[oldbutnotdead]

Not a clue what you're going to do. Have you actually got a neutral at your lightswitch or have you just assumed that the black wire is N? Personally I suspect that the neutral is at the ceiling rose so all you have present at the switch is live and load. But without a diagram I'd just be guessing.

 

[omega015]

Your post is a little confusing to try get our heads around what you've done and what wires you've tapped into and this junction box's function too. If you can provide pictures of everything involved and a wiring diagram that would be useful.

 

[securespark]

You need to look at the Wiki.

https://www.diynot.com/wiki/Electrics:Lighting-Circuit-layouts

You need to find the power supply "loop" and tap into that. The line (red) will connect to the line in the cable dropping down to the switch, the switch return will connect to the line going to the new light. The neutrals go together as do the cpc's, in separate terminals.

Don't forget to use earth sleeving and a sleeve to identify the black in the switch cable (at both ends) as a line conductor.

And if the JB is inaccessible, use an MF type.

 

[winston1]

You need to find the power supply "loop" and tap into that. /QUOTE]

No loops, lighting circuits are (or should be radials).

 

[securespark]

Next time you are close to a ceiling rose, have a look inside and see what it says next to the central terminals.

http://uk.farnell.com/mk-electric/1161whi/ceiling-rose-4-terminal/dp/7218278

 

[ban-all-sheds]

WTF is wrong with you, Winston?

 

[laferret]

Thanks for all the replies to this and my apologies for not replying sooner. I was fortunate enough to locate a wall switch for another PIR lamp within reach of the area in question so was able to tie into that circuit for the Live, Neutral and Earth. The outside light functions as required.

The mystery of the strobe continues but I wont give up. Definitely a learning process for me and I always work safely.

 

[Adam_151]

The mystery of the strobe continues but I wont give up. Definitely a learning process for me and I always work safely.

I am guessing that both the fittings are low energy types (either compact flourescent or LED)? or of another type where there is gear that incoporates a switching power supply (anything that looks a little electronic-y and connects to the mains is likely to be that these days!)

If you were to connect onto the switch wire and switch feed for another fitting, what you get is both fittings in series when the switch is off. With the switch on, the original fitting works as normal and the new fitting is shunted out (draw it out if thats not making sense). Now in the old days two fittings in series (assuming same wattages) would get 120v each and would be very dim. Modern electronic fittings (unless the designer has built in any kind of detection for the condition - rare) will attempt to start, not be able to sustain the current needed into the lamp or LED and fail back to the off state, the switching power supply will then be able to stabalise and the lamp will try and start again...

You often see LED fittings fail in this way when some of the power supply components fail or drift out of spec.