Extra neutral in kitchen ceiling roses

[CultVoid]

Hi,

I have a situation that sounds very similar to the one at http://www.diynot.com/forums/viewtopic.php?t=148126 - not sure if I should bump or not.

Anyway, I've just replaced the kitchen lights and they're working just fine, but I'm worried about the extra neutral wire in the two kitchen roses (the rest of the downstairs circuit is normal).

The lights are fed from junction boxes (I assume, there's no loop in the switch or rose), and the two kitchen lights have a live and earth on one cable, and then two separate cables each carrying a single neutral.

Is this a normal arrangement? Could the extra neutrals be for the smoke detector (which is on the downstairs light circuit), or maybe the outside light which uses a motion detector?

This is a fairly new installation and I assume all is well, but I want to satisfy my curiosity.

Many thanks if anyone can help!

Richard.

 

[ricicle]

The system has been wired in 6241Y cable. It is perfectly normal to have different configurations. Having one L and two N's is nothing unusual.

 

[1john]

I suspect you will have three red cables in the switch, two are joined in the common terminal and the third (which will go to the light) will be in L1. The two neutrals you have are a 'in' and 'out'.

 

[CultVoid]

Thanks for the info, I'm very dim indeed.

Why is it done like this on just two lights on the downstairs circuit? Is there some advantage to it, or does it serve a special purpose?

I can't find any diagrams on the web with extra neutral.

Thanks again (just curious, all is well).

 

[1john]

It is not an extra neutral, it is just another method of wiring.

The permanant live is taken to and from each switch until the end of the circuit. A switched live is taken from each switch to the relevant light. The neutrals are looped in and out of the lights until the end of the circuit. it minimised the amounts of cables in both the switch and the rose instead of using the three plate method.

 

[CultVoid]

Ah thanks that's very interesting I haven't come across that before.

Only one last thing confuses: it's only the two kitchen lights that have this, the rest of downstairs have just a neutral live and earth. Wouldn't all the lights on the circuit have the same set up? I'm sure I'm missing something simple!

 

[ricicle]

Is the kitchen an add-on extension ? Or is the switching 2 way ?
This might have been the old school electrician's way of achieving the 2 way set-up

 

[CultVoid]

No, not an extension the house has been very recently rewired.

There are two lights controlled by a single two gang switch.

 

[1john]

Impossible to say without seeing/testing it and thats all a bit pointless if everything works. How many other lights are downstairs AND on the same circuit?

 

[seasickstevie]

You must have a hidden junction box somewhere.

 

[CultVoid]

Impossible to say without seeing/testing it and thats all a bit pointless if everything works. How many other lights are downstairs AND on the same circuit?

There are two landing lights before the kitchen lights, then a further 3 lights after the kitchen lights.

The 3 lights stop working if the neutrals are disconnected. (No surprise there)

There is also an outside light and a smoke detector on this circuit.

The two landing lights and the 3 other lights are all wired with just a single neutral and live, I assumed they were using junction boxes but I was basing that on the kitchen having no loops - I'll check that later.

Sorry about this, don't worry it's just curiosity, all is working just fine and the lights I've installed look gorgeous!

 

[holmslaw]

..

 

[CultVoid]

This is very interesting, I'd no idea there was so much variation in wiring.

It could be a cost cutting measure. It's not my house, it's a friends house and when it was wired she worked with the electrician to get the costs cut down to a minimum (safely of course).

So it's possible the kitchen wiring is to save cable? I still don't understand why the rest of downstairs is "standard". I think I'll have another poke around when I'm next there at the weekend.

 

[ricicle]

The 3 lights stop working if the neutrals are disconnected. (No surprise there)

Be careful if you are playing around with single neutrals in an energised circuit as they can be live via the load and give you a nasty belt....

 

[CultVoid]

Don't worry ricicle, I never touch an energised system, I'm a nervous nerys in all situations.

I discovered the 3 downstream lights not working when the neutrals were disconnected when I was fitting the kitchen light. I hit a snag with the the fitting and decided to leave it for the next day. I terminated each cable and taped them up (leaving the neutrals unconnected), fired up the power and was confused when all the lights further along the circuit failed to come back up.

I understand now, but still don't understand why they've wired it like this.

But I've had a brilliant (snigger) idea - I've discovered she's still in touch with the installing electrician so I'll simply ask him at the weekend!

I'll report back of course!