New way to wire lighting circuits

I’ll pass on that one for the moment ?

A lot of sparks take the mains through the switch these days rather than 3 plate at the light fitting when possible, myself included.  It makes it a lot easier to fit some of these light fittings that can be quite tight.  Also easier to then just loop through down lights.  It isn't a regulation just another way of doing things.   A switched live is just that, just because the colour of the core is that of a neutral conductor doesn't make it a neutral.  It is sleeved at both ends to indicate it's function.    There are, or certainly used to be twin and earthed cable available with 2 red or brown cores.



Gary

I think someone's over-interpreted 559.5.1.208 - which says consideration should be given to providing a N at switches - to allow for power for electronic controls (the old fashioned approach of controls parasitically pinching power between L and SL doesn't work so well with low energy lamps).


   - Andy.

Indeed, not a requirement, just permitted.
559.5.1.208 Consideration shall be given to the provision of the neutral conductor, at each switch position, to

facilitate the installation of electronic switching devices.


Actually it's always been permitted,  as there are some layouts of building where to do anything else makes no sense.

If you like you could have a socket at the light switch, albeit one of limited current capacity.


There are some pretty daft sections in that bit of the regs. actually.


Try this for a giggle.
...the connecting device shall be:

(i) terminals according to BS EN 60998, or

(ii) a device for connecting a Juminaire (DCL) plug according to BS EN 61995, or

(iii) an installation coupler according to BS EN 61535, or

(iv) supporting coupler (LSC) plug according to BS 6972 or BS 700 I, or

(v) a male connector (plug) of a plug-in lighting distribution unit according to BS 5733, or

(vi) another suitable and appropriate connecting device.


Well it strikes me that if you have (iv) the other lines could safely be deleted,

unless they are suggesting they are somehow  permitted but 'unsuitable'

IIRC, in the USA there is a proposal to require a neutral at the light switch, for future flexibility for electronic controls.

In the UK, as others have already said it is permitted but not required.


There is also a lot of VERY ill informed demand for neutrals at the light switch to "improve safety" Circuits with the two conductors well seperated can give rise to electromagnetic fields, that may be harmful to health.

With a conventional 2 wire drop to a light switch, the "go" and "return" conductors are immediatly adjacenr and no significant electromagnetic field results. That however does not stop the mumsnet types from demanding neutral at every switch to "prevent rays that might harm a baby"

Thanks for the answers everyone, I'll look up that part of the Regs book.


A follow on question, what do you do with a conventional light switch in this scenario? Do you use single core browns for the common and SL and terminate the neutral in a connector or Wago, or is there a new type of light switch available with separate terminals for the L,N and E?

It makes most sense when lighting circuit is fed from below - i.e. the upstairs lights and loft lights. Then LNE arrive from below the switch and leave to the light above. Otherwise it can be wired rather as a 2 way light switch, wired in 3core+E, with 2 cores L and SL as before and the other one N.

I'm not aware of any switch with a parking contact for N, though I am aware of cases of it being stuffed in the back contact of a 2 way switch, which in effect shorts out the light when it is off.  This is not wise, and confuses the unwary - the smallest wagos or a slice of chock block are your friends.

Don't forget blue sleeving is available as well as brown.

There is a modest EMC advantage to the fed from below method (not for health, but in terms of RF pick up or emission, as in the looped out method we have in effect got an antenna like a folded dipole on the L and not the N, so any differential mode L-N signals are now radiated.) With well filtered equipment this is not necessary.

Hager switches have a loop terminal for neutrals

What do you think of the idea of powering ceiling lights from the ring main via a FCU in each room? That way the neutral conductor is available at every light switch.

The switched fuse spur as a light switch is quite common for situations on the end of a long feed, like sheds / outbuildings, or places where the lighting circuit does not need to go, such as cellars, understairs cupboards or for the wall lights in modest conservatories.

Electrically it is fine, after all combined lights and power is the continental way, and they seem to have no  issues with it.

The slight weakness is that if you do manage to trip the sockets off, you lose those lights as well, so maybe not ideal for living areas or situations like a kitchen, where being plunged into dark while holding something sharp or hot would be an issue.

Still no worse than a small flat with one RCD for everything, and there are lots of those.

regards Mike.