Wiring

I am planning on converting an existing porch into a downstairs toilet with wash hand basin.

I have discussed this with the BCO, who initially wanted this to be Part P approved, but following my query agreed that wiring in this area was not subject to Part P, I will be wiring lighting into the area myself. This will be two halogen/LED GU10 downlights with a one way switch outside the toilet, plus a feed to a lighted wall mirror.

I intend using old 'stock' black/red 1.5mm wiring with the feed taken from the existing downstairs lighting radial circuit.

I have one question, but would happily receive advice. The question is, what wiring should be used from the light fittings to the switch? Historically I would have chosen twin red 1.5mm, what now?

Paul R

Reply to
Paul R
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If you have twin and earth black/red, use that and sleeve the black with red PVC sleeve as per how you would always have done it (i.e. red is permanent live and black/red sleeve is switched live).

Reply to
Dave Osborne

On Wed, 22 Sep 2010 12:02:50 +0100 someone who may be Paul R wrote this:-

Dave has given a good reply. However, as a broader point brown and brown coloured cable is available, though TLC only seem to do it in

1.0.

Alternatively brown and blue could be used, with the blue sleeved in brown.

Reply to
David Hansen

Just spotted it at Toolstation

Twin & Earth (6242Y) 2 Brown Cores

Cat no's

21810 1.5mm² x 10m - £8.48 20111 1.5mm² x 25m - £12.98 89801 1.5mm² x 50m - £21.88
Reply to
Adrian C

I have banned the brown brown cable from my van. It stops mistakes happening on first fix.

Reply to
ARWadsworth

: >> The question is, : >> what wiring should be used from the light fittings to the switch? : >> Historically I would have chosen twin red 1.5mm, what now? : >

: > Dave has given a good reply. However, as a broader point brown and : > brown coloured cable is available, though TLC only seem to do it in : > 1.0. : : I have banned the brown brown cable from my van. It stops mistakes happening : on first fix. :

It also makes for slower fault finding, with brown/blue or the older red/black and (indicating) sleeves it's quick and easy to see which wire is - should be - the permanent live and switched live at either end.

Reply to
Jerry

I helped a mate convert his garage into among other things a downstairs loo with sink. I just did a minor works certificate for the BCO.

You can use the modern brown/brown equivalent, or use conventional brown/blue and sleeve appropriately.

Reply to
John Rumm

Not really, since there is no convention as to which wire should be which. Personally I use the re/brown as the permanent live and the sleeved one as switched, but that is not universally copied. Its also quite common to find no sleeving at all in practice which makes it more fun when someone says, I took the ceiling rose off and now I don't know what to do with all those wires!

Reply to
John Rumm

: > :>> The question is, : > :>> what wiring should be used from the light fittings to the : > switch? : > :>> Historically I would have chosen twin red 1.5mm, what now? : > :>

: > :> Dave has given a good reply. However, as a broader point : > brown and : > :> brown coloured cable is available, though TLC only seem to do : > it in : > :> 1.0. : > : : > : I have banned the brown brown cable from my van. It stops : > mistakes happening : > : on first fix. : > : : >

: > It also makes for slower fault finding, with brown/blue or the : > older red/black and (indicating) sleeves it's quick and easy to : > see which wire is - should be - the permanent live and switched : > live at either end. : : Not really, since there is no convention as to which wire should be : which.

Perhaps on your Island John, but here in the UK...

Reply to
Jerry

I can only conclude Jerry that you have little or no practical experience with UK domestic wiring.

IME, if one encounters red/red or brown/brown in a lighting circuit, then you can have a fair degree of confidence that it is the switch drop cable. Hence that stage of fault finding (i.e. cable identification) is aided by use of said cable. In reality it is far more common to find normal two colour T&E in use for switch drops. It is also alarmingly common, to find no over sleeving or other identification in use either.

Reply to
John Rumm

When is there ever any need to know which is which?

Reply to
Ronald Raygun

On Thu, 23 Sep 2010 13:34:13 +0100 someone who may be Ronald Raygun wrote this:-

For a start it is useful when working on ceiling roses. Is that blue (or black) insulated wire a switched live, or a neutral?

Reply to
David Hansen

: > :> :>> The question is, : > :> :>> what wiring should be used from the light fittings to : > the : > :> switch? : > :> :>> Historically I would have chosen twin red 1.5mm, what : > now? : > :> :>

: > :> :> Dave has given a good reply. However, as a broader point : > :> brown and : > :> :> brown coloured cable is available, though TLC only seem : > to do : > :> it in : > :> :>

1.0. : > :> : : > :> : I have banned the brown brown cable from my van. It stops : > :> mistakes happening : > :> : on first fix. : > :> : : > :>

: > :> It also makes for slower fault finding, with brown/blue or : > the : > :> older red/black and (indicating) sleeves it's quick and easy : > to : > :> see which wire is - should be - the permanent live and : > switched : > :> live at either end. : > : : > : Not really, since there is no convention as to which wire : > should be : > : which. : >

: > Perhaps on your Island John, but here in the UK... : : : I can only conclude Jerry that you have little or no practical : experience with UK domestic wiring.

I have plenty, dating back to wiring that was likely installed in the 1920s through to the present day. I have also experience of working on conduit/trunking protected industrial wiring and I can tell you that having two wires the same colour within the switch box is no help in telling were each wire goes without the use of a circuit tester of some sort.

: : IME, if one encounters red/red or brown/brown in a lighting circuit, : then you can have a fair degree of confidence that it is the switch drop : cable. Hence that stage of fault finding (i.e. cable identification) is : aided by use of said cable.

Well yes, I can see were that might be useful when someone hacks their way through the wiring buried in the wall or under the floor but most people will already know that they are working within a switch backing box or ceiling rose, even if they are working on a junction box of some sort they are likely to know what circuit they are working on - and were two colour T&E has been used with a marker sleeve it is very obvious that it is a switch drop.

In reality it is far more common to find : normal two colour T&E in use for switch drops. It is also alarmingly : common, to find no over sleeving or other identification in use either. :

If it's so alarming to you John then perhaps you have not the common sense to be working on electrical wiring, after all the fact that you will have removed a switch plate and still not KNOW that you are working on a lighting circuit, or even worse, have not installed a lighting circuit...

Reply to
Jerry

: >When is there ever any need to know which is which? : : For a start it is useful when working on ceiling roses. Is that blue : (or black) insulated wire a switched live, or a neutral? :

Or converting to a two-way (or more, with intermediate) switch and circuit.

Also, although rare in domestic wiring, when adding more gangs to the switch plate, were one wants to use the existing permanent live to feed the other gangs.

Reply to
Jerry

A ceiling rose typically has three cables (not counting the one to the lightbulb), all of them twin and earth. One cable comes from the previous rose and one goes to the next, they both carry permanent live and neutral. The third cable goes to the switch.

Now, if you've disconnected everything and can't remember which is the switch cable, is there a problem? No, because either the switch cable will have two wires the same colour, and that immediately identifies it, or else it will look the same as the other two cables, in which case the identification problem is easily solved as follows:

Just connect all three browns together, leaving the blues disconnected for the time being, turn on the power, and probe the three blues in turn.

Zero, one, or two of them will be live. [*]

Go and operate your local switch, and then one of the blues should have changed state either to live or to dead. That'll be the one in the switch cable. You can then turn off the power and complete the wiring job.

[*] If the roses are ring-wired, then the blues from both the previous and the next rose will be connected to mains neutral at the consumer unit, and therefore will both be dead, so at most the one blue from the switch will be live, if it's on. Operating the switch will make it go dead.

If the roses are simply daisy-chained, up to two of the blues may be live. One of them will be the local switch, if on. The other will be the neutral return from the downstream rose(s), if one of them is switched on and dragging the dangling neutral up to live.

Reply to
Ronald Raygun

Again it won't be necessary to distinguish live from switched live at the rose end, nor will it be necessary to distinguish them at the switch box which has the cable going to the rose. The switch (or series of switches) will either join these two wires together or not.

The series of two or more switches will have the permanent live going into the first switch, and the final switched live coming out of the last one, but there is no reason why they can't be connected the other way round. There will of course be two intermediate switched lives (i.e. one will always be live and the other not, but which one is live depends on the state of all the switches between that point and the permanent live feed) running from switch to switch along the series.

Fair enough.

Reply to
Ronald Raygun

Well, that's true enough, but the trouble with ceiling roses is that they're bloody high up. Therefore I suggest that it's easier and safer to probe one-handed with one of those little screwdrivers with a neon light in them, while using your other hand either to hold onto the step ladder, or to steady yourself against the ceiling while precariously balanced on the top step, than it is to wield one probe in each hand while holding the meter itself between your teeth.

Reply to
Ronald Raygun

There is no need to go playing about with the circuit while energised. For most cases just turning the circuit off, and then measuring resistance between L&N on each cable, while operating the switch will soon find it.

Reply to
John Rumm

No dear boy, alarming in the sense that it has been required practice (never mind just common sense) to identify wires used for purposes other than that indicated by their actual colour for many many years, and yet so few people actually seem to do it.

Reply to
John Rumm

Or for a safer working method simply turn the power off and put a continuity tester on turn between the brown and blues on each cable. The one that goes from open circuit to closed circuit (or vice versa) when the switch is operated is the switch wire.

And I have never seen a lighting circuit wired as a ring.

Cheers

Reply to
ARWadsworth

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