Help wiring double pole pull cord switch

BudgetBoy

Hi

Pull cord for the extractor fan in my shower packed in. Googled images of the switch and it's a double pole so bought one. Need advice on the wiring please as the marking on the new switch are different.

Old switch is a Tenby MG888. It was put in by the house builder. Only controls the extractor fan. Simple on/off with no overrun.

The light in the bathroom is controlled by a normal wall mounted switch outside the bathroom.


So there are 3 cables feeding into this switch which surprised me!

All 3 yellow earth wires go into 1 earth terminal.
1 black neutral wire goes into a terminal marked (2way)
2 black neutrals go into an unmarked terminal.
1 red live goes into a terminal marked (1 way)
2 red live go into a terminal marked (COM)


The new switch has 1 earth
L out
N out
L in
N in

So the question is which way round do the wires go?..

Thanks in advance
Ste

Le_Kirk

Your old switch is a 2-way pull cord switch and is normally used when something can be switched ON with one switch and OFF with another switch. Is that the case with your fan? What you have bought is exactly what you asked for a double pole pull cord switch, where live and neutral go in and live and neutral go out. This will be fine PROVIDING you can determine what the wires in the old switch do. It may be that you (or an electrician if you are not confident/competent) will have to split the wires and see what is on each (live or neutral). However, you could take the double pole pull cord back and just buy a pull cord 2-way switch and wire it EXACTLY the same as presently.

Owain_Moneysaver

NOTE: Black wires are not necessarily neutrals. They may be switched lives (and should have been sleeved red)

If it's a standard dp switch with the feed looping in and out, and cable to the fan:

1 black neutral wire goes into a terminal marked (2way) N OUT
2 black neutrals go into an unmarked terminal. N IN
1 red live goes into a terminal marked (1 way) L OUT
2 red live go into a terminal marked (COM) L IN

Do you have one ducted fan shared between two rooms with separate light switches in each room? If so, you'll need to work out the wire colours from this:

LIVE -------------- SWa Pole 1----------- LIGHT -- Neutral 
                 | 
                 |-- SWa Pole 2----- 
                                   | 
                                   | 
                                   -- SHARED -- Neutral 
                                   -- FAN 
                                   | 
                                   | 
                 |-- SWb Pole 2----- 
                 | 
 LIVE -------------- SWb Pole 1 ---------- LIGHT  -- Neutral

Owain_Moneysaver

The MG888 was a double pole 5A pull switch. The terminal markings do not reflect the switch mechanism. Presumably they didn't mould a back cover assembly specially for this item, which would be less popular.

BudgetBoy

Thanks for quick replays. It's in a en suite so only the one switch controls the one extractor.

The new switch I've bought looks the same but the markings are different, hence the confusion. Basically need to know are the 2 wires together the IN and the single wire the OUT going to the fan itself.

Not an electrician but confident changing like for like on light fittings and plugs etc. This has me confused.

Debbie_Savard

It's possible that

1) The fan used to be a different model with a permanent live for a timer
2) The bathroom light used to be controlled by the pull cord

Either way, you could be looking at the old wiring that wasn't removed.

NB it's now accepted practice to install a 3-pole isolator switch and fuse down to 3A when working on bathroom extractor fans.

BudgetBoy

Think I might need to get an expert in! Cheers all who've taken time to reply. :beer:

BudgetBoy

Debbie_Savard wrote: »

It's possible that

1) The fan used to be a different model with a permanent live for a timer
2) The bathroom light used to be controlled by the pull cord

Either way, you could be looking at the old wiring that wasn't removed.

NB it's now accepted practice to install a 3-pole isolator switch and fuse down to 3A when working on bathroom extractor fans.

Thanks Debbie. The house is only 18 years old. Can definitely rule out the switch controlling the light. Only ever been controlled via the wall switch in our bedroom.

Owain_Moneysaver

BudgetBoy wrote: »

Basically need to know are the 2 wires together the IN and the single wire the OUT going to the fan itself.

Probably, see my above post.

Ectophile

It may be that the switch doesn't control the light, but the wiring to the light has been looped through this switch. Hence the extra red and black wires.


It's quite common on lighting circuits for the wires to be "daisy chained" from one outlet to the next.

Jjohns

My new light doesn’t have any markings on it for the wires can you help ? You