how to rewire bathroom pull switch to regular light switch

[Nick]

I have relocated an existing pull switch to outside its bathroom. Now I want to change it to a 'normal' switch. However, it has more wires than terminals in a normal switch. I think I need a special type of switch (boiler?), with more terminals. Can anyone advise me whch type of switch I need and how it should be wired?

The existing pull switch has four terminals and an earth terminal. It is wired;

- Earth (which I assume I wire to the new switches metal box)

- Red to one terminal

- Black to one terminal

- Second red shared to two terminals by way of a link

The switch activates a ceiling light and also a shared extractor fan. Any help would be much appreciated. Nick

[BigWallop]

The two reds should be in one terminal point on the switch, the COM terminal. The black should actually be covered with a red coloured sleeving to mark it as a switched live to the light fitting on the ceiling. The setup you have is one red is from the mains and is the live feed to both the switch and also the continuous feed for the fan. The black from the fan will be connected to the black inside the ceiling rose of the light fitting along with a switched red to make the timer in the fan come on when the light does.

[N. Thornton]

you'll have L N and E arriving to the switch E N and switched live going to the light E N L and switched live going to the fan.

All you need is a light switch. Check it out with a multimeter with the mains power off, and if in any doubt, not competent etc, leave it all well alone.

Regards, NT

[Nick]

Thanks for this info, but I am still a little unsure of how to proceed. Am I right that a normal light switch (with one COM and one L1 terminal) will not be usable?

If I need another type of switch (a normal switch with four terminals is what the other bathroom has) can you tell me what this is called, and which wires go where?

Thanks very much again for your reply. Cheers Nick

[Lurch]

Sorry, but I hope you haven't rewired as per the other answers. You need a douple pole switch, usually rated at 20A or similar as used for immersion heaters. The reason this type is used is that the fan is shared between two rooms I would assume. This means in essence that if you connected them all together as per the other posts then every time you switch the light on in one room the light in the other rrom will come on. The douple pole switch prevents this by providing an isolated fan and light switch on one plate. When you get your double pole switch you will notice that one pole will say 'L' and the other 'N'. Ignore this, it isn't a requirement, more a guide. You need to connect the 2 reds that are looped int the 'L' and 'N' terminals on the 'MAINS' or 'SUPPLY' side. The red and black switch wires need to go to the two terminals 'L' and 'N' marked 'LOAD', any way round will be fine. Remember a double pole switch will need a deeper box in the wall than a normal light swtch. This is exacly how it is done at my house and I have done the same as you, moved the pull switch to a wall switch outside. You don't live round the corner from me do you! Any more queries, just ask.

SJW A.C.S. Ltd.

[Owain]

"Nick" wrote | Thanks for this info, but I am still a little unsure of how to | proceed. Am I right that a normal light switch (with one COM | and one L1 terminal) will not be usable? | If I need another type of switch (a normal switch with four | terminals is what the other bathroom has) can you tell me | what this is called, and which wires go where?

I don't think you've got a ceiling light switch - which would be single-pole two-way (COM, L1 and L2 terminals)

I think you've got a DOUBLE-POLE ceiling switch of the type used for electric showers, one pole is doing the light, and the other pole is doing the *shared* fan. Is it a square plate and decidedly chunky in style? - they're usually rated at 30 or 45A for showers rather than 6A for lightswitches.

IE wired something like this (SWa = switch a, which has two poles)

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

This would correspond to your

- Red to one terminal

- Black to one terminal

- Second red shared to two terminals by way of a link

The "second red shared to two" would be the live linking to SWa Pole1 and SWa Pole 2 above.

Using this, when either switch is on the shared fan gets electricity, as does the switch's own light, but the electricity can't run back through the other switch to the other light.

If this is the case then I think it contravenes the Regs (a) by the colour coding - it sounds as though the Black to one terminal is the live to either the light or fan (b) by not running line and neutral of a circuit in parallel close together.

It's possible the 'normal' switch with four terminals the other bathroom has is an INTERMEDIATE light switch, but I don't see how it could be wired the same way because AFAIK Intermediate switches aren't available in pull-cord.

If the 'normal' switch the other bathroom has is also a bit chunkier (and maybe a red rocker) than a light switch it's almost certainly a DP switch.

God help you is all I can say, because my head is starting to hurt with the strangeness of it all :-)

Owain

[BigWallop]

A normal switch is OK to use, just put the two reds into the COM terminal and switched live (black) to the L1 terminal. The reason for the double pole switch being used in the pull cord is beyond me, because the only thing it is doing is switching the same red on at the same time as the switched live (black). If the fan continues to run all the time, then you'll need to move the red that feeds it over to the L1 terminal and have it switch on with the black.

Find out which red is the actual Feed Live to the switch, then you can mark it with a pen or pencil to make sure you don't get it mixed up with the switched red, and then connect it in to the COM terminal of the switch. You already know the black is the switched live, so this is easy to put in place on the L1 terminal and get it out of the way as well. Before you connect the other red to anything, and making sure you don't touch the metal parts of it, touch against the red in the COM terminal. If the fan begins to run, then you have it in the wrong side of the switch. This means it is connected in with black in the L1 terminal.

[BigWallop]

Excuse me, but when the double pole switch is closed both ends become live at the same time. So why not use a single pole switch and connect the switched live (black) and the other red together ? That way you won't have to link the two poles together. You're literally making the more expensive double switch into a single pole one. Seems a bit silly to me. :-))

[Lurch]

Basic concept of the answer is correct, pretty much as my post further down! However,

Not neccessarilly, you can get quite unobtrusively small cieling mounted 20A pull switches.

Pretty good, You should do more!

This doesn't contravene the regs in any instance. It is perfectly acceptable to use black as a switch wire as long as it is marked with red sleeving or similar at all connections. Live and neutral can run wherever they like, as long as they are connected properly and routed in accordance with the regs.

As I said, 20A DP clg switches look like normal one's, same size and external appearance.

Obviously you're not an electrician then!! I've recently finished wiring 16 fans, 6 speed controllers, 8 automatic changover units all with varios methods of switching. I could explain how I did that if you want!?

SJW A.C.S. Ltd.

[Lurch]

Don't do this, it won't work.

SJW A.C.S. Ltd.

[Lurch]

That's not why it's double pole, it's to prevent the fan switch wire becoming live from the other end thus livening the light switch wire if it were directly connected. The way it's wired it will not travel through the switch as it is on a seperate pole. There will be the same setup on all other rroms controlling this fan as well. I've wired loads of fans like that. Trust me, I do it for a living, if I can't get this right I shouldn't be doing it!!

SJW A.C.S. Ltd.

[BigWallop]

Oooohhh !!! I don't like that kind of setup. If I have anything inter-connected I use a relay to isolate the other switches from the appliance. That way I know that only one feed is going to the appliance at a time. The way you talk about would mean that when both switches are on the appliance is being fed from two points. I don't like that one bit.

[Lurch]

Good idea in theory, but you don't get relays and fancy control systems in houses on building sites. Chuck 'em up I think you'll find would be the motto! In my defence I never said it was a good way, I just said I've done it a lot in the past and it works. There should be, if the house is new enough, a fan isolator close to the fan in the loft. The way I have wired them there has only been one three core and earth going to the fan, all the connections being made in the back of the switch. This would certainly confuse any DIYer taking the plate off!! It's not really much different from two or three way lighting circuits, the live can be passed through the circuit in different ways, i.e. all wires are designated 'live' but aren't neccessarilly live at all times and not always fed from the same direction, but once the correct fuse is pulled it is all safe anyway. Or have you installed relays on all your 2 way lighting as well? ;-)

SJW A.C.S. Ltd.

[BigWallop]

I've always put isolator relays beside, or on, the remote appliance so it is fed from only live at a time. For two, three or more way lighting there is only one feed at a time going to the light fittings because of the switching configuration allowing only one path at a time to become live, so the need for relays isn't an issue in this type of installation. For a remote appliance that can, and is, being fed with more than one live conductor to its live terminal, and from more than one switched point all in different places in the house, then I think it safer to use local relays at the appliance to take the other feeds away from it directly. The cost of relays and a box to site them in can't surely be an issue because they're the same price as a single pole switch and back box.

[Tux]

It's not that I'm disagreeing with you, I can see where you're coming from, I just know that you won't get this in new houses. It becomes too much a maintenance issue otherwise. If you know what you're looking at wwith regard to an electrical installation relays and such like aren't neccessary. Unfortunately thats the way the industry is, no-one HAS to do anything a particular way, and often gets done any old how. I'm quite happy with my way of doing it and you yours, there's no right and wrong in these two methods, just the usual way and your way!

[BigWallop]

Oh I believe you, because those are the installations I'm commonly sent to, to make them safe after the DIYer has done something nasty to themselves when they tried to fix it. So I know it goes on and I still don't like it. :-))

[Nick]

Gentlemen, thank you all (esp. Lurch aka SJW) for sharing your knowledge. Yes the fan is shared and the 'immersion switch' rings a bell as regards what was (professionally) fitted to the other bathroom (which shares the fan). I knew the new switch had something to do with boilers :o) I now have the info I need to complete the job.

SJW, I am in Bournemouth as you asked, but want to do this myself. If I get stuck I will certainly drop you a line. Cheers

[Rob Nicholson]

I'm not quite sure what the OP meant by shared extractor fan but I'm hoping to do something similar. I understand how the system works with switched live running the light and switched live + unswitched live running the extractor fan (with the unswitched live used to power the fan after the switch is turned off).

I can appreciated the suggestion for a double pole switch instead of simply splitting the switched live on the output side of the switch to the fan & light but a 20A rating seems rather OTT for a 100 watt bulb plus small extractor fan?

Cheers, Rob.

[Owain]

"Lurch" wrote | "Owain" wrote: | Basic concept of the answer is correct, pretty much as my post further | down! However,

Yes, if I'd waited 20 minutes I could have read your answer instead of working it out for myself!

| Not neccessarilly, you can get quite unobtrusively small cieling | mounted 20A pull switches.

Must admit to not having seen those. If I had I might have jumped to the conclusion quicker.

Which reminds me, to go and screw the bathroom light switch back on the ceiling ...

One minute to tighten the switch and five minutes to clean up the broken glass from the picture I knocked over taking the torch off the shelf.

| >IE wired something like this (SWa = switch a, which has two poles) [snip ASCII art] | Pretty good, You should do more!

Thank you, once it's drawn out it's quite logical.

| >If this is the case then I think it contravenes the Regs (a) by the | >colour coding - it sounds as though the Black to one terminal is | >the live to either the light or fan (b) by not running line and | >neutral of a circuit in parallel close together. | This doesn't contravene the regs in any instance. It is perfectly | acceptable to use black as a switch wire as long as it is marked with | red sleeving or similar at all connections.

Which the OP's weren't. Mind you I suppose *all* his wires should be red, which would just make things even more complicated.

| >God help you is all I can say, because my head is starting to hurt | >with the strangeness of it all :-) | Obviously you're not an electrician then!! I've recently finished | wiring 16 fans, 6 speed controllers, 8 automatic changover units all | with varios methods of switching. I could explain how I did that if | you want!?

It's perfectly straightforward once one understands "oh THAT'S how they did it!" Just hadn't seen this configuration before. And it was past my bedtime :-)

Owain

[Owain]

"Rob Nicholson" wrote | > The reason this type is used is that the fan is shared between | > two rooms I would assume. | I'm not quite sure what the OP meant by shared extractor fan but | I'm hoping to do something similar. I understand how the system | works with switched live running the light and switched live + | unswitched live running the extractor fan (with the unswitched | live used to power the fan after the switch is turned off).

If you pull up my ASCII art earlier in the thread, the two Lives going in to the fan (one from each switch) would go into the Switched Live or Trigger of your over-run-timer. You'd need a separate run of Permanent Live to the Live of the fan.

| I can appreciated the suggestion for a double pole switch instead of | simply splitting the switched live on the output side of the switch | to the fan & light but a 20A rating seems rather OTT for a 100 watt | bulb plus small extractor fan?

It's what's available

Owain