Wiring replacement pull cord switch

[Larches]

I need to replace a pull cord switch for a shower extractor fan, but would appreciate advice regarding wiring as the old and new switches are different types. I'm attaching a picture of each.

The existing switch has common, L1 and L2, with the lives currently going together into COM and both neutrals terminated together - as can be seen in the photo.

The new switch is double pole and has "in" L & N and "out" L & N.

Can anyone confirm the correct config for the new switch please (and what's with the fan 'earth' to L2 on the existing switch)?

Also, there's no hole on the new switch to bring the cables through (as presumably there wasn't on the old one originally either . There are two oblong recesses that are presumably to be cut out as required, but it's still pretty thick, solid plastic - what's the easiest way of tackling this (without risking knackering anything)?

Thanks!

 

[Andy™]

your fan should be wired in 4 core flex not 3 core using the earth as a live. whoever installed it has bodged it

 

[Murdoch]

Or replace the timer fan with a non timer model......... And wire it using the existing 3c with the earth being the earth...

 

[ProDave]

+1 to the above.

Assuming it's an upstairs bathroom with access to the loft, it should be easy to replace the 2 core and earth cable with a 3 core and earth cable. Then we can tell you how to wire it. The wiring will be different as your new switch is a double pole switch with a neon "on" indicator lamp.

There is a rectangular knock out for cable entry bottom right as shown in the picture.
 

 

[Lurch]

your fan should be wired in 4 core flex not 3 core using the earth as a live. whoever installed it has bodged it

No they haven't. Please point me to the regulation which disallows this practice.

Yes it would be ideal to wire it in 4 core flex but using 3 core with the G/Y sleeved is not bodging it and there is nothing wrong with what is there.

 

[steptoe]

I'm sure this came up before,

I was always under the understanding that a G/Y marked cable could not be over marked for any use other than an earth/CPC,

But, after the last escapade, I'm unsure if anyone ever came up with a definitive regulation or not, :C

So that's of no help to anyone whatsoever really,,,, :|

 

[Lurch]

I'm sure this came up before,

I was always under the understanding that a G/Y marked cable could not be over marked for any use other than an earth/CPC,

But, after the last escapade, I'm unsure if anyone ever came up with a definitive regulation or not, :C

I'd imagine it has come up a few times. I would concede that this is perhaps "open to interpretation" but using G/Y in a flexible multicore cable is not expressly prohibited.

If you are cutting cables mid run on the assumption that G/Y = CPC, Brown = L & Blue = N then you are going to come a cropper before long. If this was the case brown/blue switch drops would be outlawed too.

 

[SPECIAL LOCATION]

Personally I wouldn't use a Grn/Yell as anything other than a protective conductor.... ref 514.4.2:



I'd also be interested to know if this 230v Fan is in the correct zone in the bathroom?

or should it be a 12V?

If its a pain in the bum to replace the cable..  long run behind tiles etc...

I'd probably convert it to 12v and stick a transformer and timer close to the switch with a new bit of 3 core + E doing the live & switched lives..

and use the flex to run the 12v to the fan.

Guinness

 

[Lurch]

There is still nothing in those regulations that specifically exclude the use of the G/Y in a multicore cable as a live conductor.

 

[steptoe]

Its a funny one,

Can anyone point out one of the regs that is NOT ambiguous,?

An internet Pint for the winner,  Guinness

There is still nothing in those regulations that specifically exclude the use of the G/Y in a multicore cable as a live conductor.

I'd agree, 

With that reg it would appear to be merely a 'good practice' thing, and, if needs must,,,,        

 

[SPECIAL LOCATION]

There is still nothing in those regulations that specifically exclude the use of the G/Y in a multicore cable as a live conductor.

There is nothing that says it is an acceptable use.....

. If this was the case brown/blue switch drops would be outlawed too.

Brown & Blue switch drops ..  (sleeved brown)

and two switching with Brown / Black / Grey    (also sleeved brown)

Are specifically mentioned in Appendix 7 top of page 436.... as being acceptable

But...  I can't see any mention stating that grn/yel over-sleeved brown is an acceptable practice anywhere????

We do also have the Reg; 412.2.3.2  (pg 66) that requires a CPC to be run to each point and accessory in a circuit supplying one or more items of Class II equipment.

So strictly speaking a CPC would still need to be run to this fan to comply with BS7671.

opcorn

 

[Andy™]

There is still nothing in those regulations that specifically exclude the use of the G/Y in a multicore cable as a live conductor.

correct, but an earth should be taken to every point. so its still wired wrong

 

[Lurch]

but an earth should be taken to every point. so its still wired wrong

I could probably class that as the appliance cord, and as such it doesn't need an earth if the appliance is class 2. Again, the ambiguity of the regs would make it hard to argue that as being incorrect, specifically.

 

[kerching]

Anybody want to email the Technical Helpline at NICEIC?

i feel,that I personally will not get an answer  :innocent

like others I am sure I have seen somewhere that it is acceptable, prob in a magazine

but I cannot remember where or when

 

[rapparee]

 If this was the case brown/blue switch drops would be outlawed too.

Actually, in ireland brown/blue switch drops are outlawed. We use twin brown.

I can't remember the reg @Risteard will be able to quote it.

 

[steptoe]

I remember never being allowed to use red/black in norn iron, always had to be twin red, and nihe specified big earth 1.5, ie, a 1.5 with a 1.5 earth. 

 

[Geoff1946]

I feel a little sorry for the original poster who must be quite bewildered by the discussion he has triggered.  What he has there may be incorrect to regs but in my opinion isn't actually unsafe. May I suggest that the following is helpful.

Lin  =  Red + Brown 

Nin =  Black

Lout = The sleeved green core of the flex

Nout = Blue

 Terminate the incoming (unused) earth core in the terminal provided in the new box, just as it was in the old.

As regards opening up the knockouts, if they are tough to pierce start with a small drill and open up with a file. As  space appears tight in the new switch it will probably be best to separate the incoming and outgoing cables and use both knockouts. Shorten the wires to lay neatly, with the cable sheaths finishing just inside the box. (i.e. do not just push spare wire back up into the void.)

 

[Adrian]

Personally I wouldn't use a Grn/Yell as anything other than a protective conductor.... ref 514.4.2:

View attachment 7826

I'd also be interested to know if this 230v Fan is in the correct zone in the bathroom?

or should it be a 12V?

And what zone would that be ?

As long as the fan is ip4x(which most are) and RCD protected why waste money on a 12v fan

Guinness

 

[Andy™]

Lin  =  Red + Brown 

Nin =  Black

Lout = The sleeved green core of the flex

Nout = Blue

er... if it fan has a timer (which i would assume for how its been wired) then that wiring method will stop the timer function from working...

L in brown & red

L out g/y sleeved brown

N in black & blue

a bit like a job a long time ago where the architect insisted on DP switching for the lights and refused to listen to why it should be SP, then finally agree'd to SP after the job was complete and pointed out that the emergency lights come on every time you turn the light switch off...

 

[sprocketflup]

There is still nothing in those regulations that specifically exclude the use of the G/Y in a multicore cable as a live conductor.

Its a funny one,

Can anyone point out one of the regs that is NOT ambiguous,?

An internet Pint for the winner,  Guinness

I'd agree, 

With that reg it would appear to be merely a 'good practice' thing, and, if needs must,,,,        

Hang on, I'm lost here, theres a reg there that states "Green+yellow shall be used exclusively for identification of a protective conductor, and this combination shall not be used for any other purpose." Next bit says it shall not be oversleeved at its terminations.

So whoever has wired that switch/fan has used green/yellow as a live conductor, and oversleeved it, yet you say theres nothing in the regs to say not to do so?

I'm not seeing your logic.