bathroom extractor and pull switch

[benitezhastogo]

hi all
a small wiring problem!
i have a new extractor to fit replacing the old one. (power taken from light)the old one was not switched, came on with the light. can i wire this up to include a pull switch for the fan? if so how should the wiring go? the old cable from the light is three core white. this went to the old fan. i was going to take this cable to the pull switch and a new cable 1.5mm t+e from the pull switch to the fan. is this ok if it is how do you wire it.
i appreciate your time thanks.
the pull switch has L1 L2 COMM , the fan has L1 N L Lt .

 

[electronicsuk]

Need more information about the old wiring. You say 3 core - is that two core and earth, or three core and earth?

If the former, some alteration of the wiring will be required, which will mean access to the ceiling rose/fitting/junction box, or wherever the fan gets its supply from. Otherwise, you will always need to have the light on to use the fan.

 

[benitezhastogo]

Need more information about the old wiring. You say 3 core - is that two core and earth, or three core and earth?

If the former, some alteration of the wiring will be required, which will mean access to the ceiling rose/fitting/junction box, or wherever the fan gets its supply from. Otherwise, you will always need to have the light on to use the fan.

hi again, the old cable is 2 core and earth, ( went from light to fan!) i would appreciate advice on getting fan to run independently of light. but via a pull switch..

 

[wingcoax]

Idealy you should run three core and earth from ceiling rose to isolator outside room and then three core and earth to fan,your switch can be linked internal in the isolator back box, remembering that you will need a permanent live to give you the overrun timing on your fan.
Please bear in min that this will put you under "PART P" of building regs as this is in a "special location"

 

[electronicsuk]

In that case, you need to trace the supply to the fan back to wherever it meets the lighting circuit. There, the neutral and earth connections can stay as-is, but the live connection will need to be moved out of the switched live terminal(s) and into the live loop terminals.

Although it doesn't cover your specific application, there is a diagram in the Wiki here that may help you understand the connections at the light fitting.

Once you've sorted out the supply, installing the switch is fairly basic. Break into the existing supply cable, link the neutrals together in a terminal block, and then sleeve and do the same with the earths. You may find there is already a terminal where you can connect your earth wires in the surface mount pattress for the switch, or even on the switch itself.

The incoming live wire should connect to COM on the switch, and the outgoing live to L1.

The wiring of the fan will be as per the manufacturers instructions. It sounds as if you've purchased a timer fan from the terminal markings you mention. If you wish to utilise the timer function, you'll need to change the entire run of 2 core + earth cable to 3 core + earth. If you don't need that feature, it will be possible to use the fan with the existing cable once you've made the necessary alterations as I've described.

Without seeing the instructions for the fan, I can't be any more specific. It would seem odd to have four terminals, unless the fan has both a high and low speed.

 

[ban-all-sheds]

Please bear in min that this will put you under "PART P" of building regs

Whatever he does it will be within the scope of Part P. Part P (in fact all of the Building Regulations) applies to any work whatsoever on fixed electrical cables or fixed electrical equipment located on the consumer’s side of the electricity supply meter which operate at low or extra-low voltage and are—
(a) in or attached to a dwelling;
(b) in the common parts of a building serving one or more dwellings, but excluding power supplies to lifts;
(c) in a building that receives its electricity from a source located within or shared with a dwelling; or
(d) in a garden or in or on land associated with a building where the electricity is from a source located within or shared with a dwelling.


[EDIT]
Stupid question (written because I completely failed to spot the subject of the topic) removed.

[/EDIT]

 

[benitezhastogo]

In that case, you need to trace the supply to the fan back to wherever it meets the lighting circuit. There, the neutral and earth connections can stay as-is, but the live connection will need to be moved out of the switched live terminal(s) and into the live loop terminals.

Although it doesn't cover your specific application, there is a diagram in the Wiki here that may help you understand the connections at the light fitting.

Once you've sorted out the supply, installing the switch is fairly basic. Break into the existing supply cable, link the neutrals together in a terminal block, and then sleeve and do the same with the earths. You may find there is already a terminal where you can connect your earth wires in the surface mount pattress for the switch, or even on the switch itself.

The incoming live wire should connect to COM on the switch, and the outgoing live to L1.

The wiring of the fan will be as per the manufacturers instructions. It sounds as if you've purchased a timer fan from the terminal markings you mention. If you wish to utilise the timer function, you'll need to change the entire run of 2 core + earth cable to 3 core + earth. If you don't need that feature, it will be possible to use the fan with the existing cable once you've made the necessary alterations as I've described.

Without seeing the instructions for the fan, I can't be any more specific. It would seem odd to have four terminals, unless the fan has both a high and low speed.

thanks for the responses.
the question remains instead of an isolator switch outside the bathroom, is it possible to use a pull switch inside.? linked from the light to the fan if so how should the wiring be,

 

[benitezhastogo]

In that case, you need to trace the supply to the fan back to wherever it meets the lighting circuit. There, the neutral and earth connections can stay as-is, but the live connection will need to be moved out of the switched live terminal(s) and into the live loop terminals.

Although it doesn't cover your specific application, there is a diagram in the Wiki here that may help you understand the connections at the light fitting.

Once you've sorted out the supply, installing the switch is fairly basic. Break into the existing supply cable, link the neutrals together in a terminal block, and then sleeve and do the same with the earths. You may find there is already a terminal where you can connect your earth wires in the surface mount pattress for the switch, or even on the switch itself.

The incoming live wire should connect to COM on the switch, and the outgoing live to L1.

The wiring of the fan will be as per the manufacturers instructions. It sounds as if you've purchased a timer fan from the terminal markings you mention. If you wish to utilise the timer function, you'll need to change the entire run of 2 core + earth cable to 3 core + earth. If you don't need that feature, it will be possible to use the fan with the existing cable once you've made the necessary alterations as I've described.

Without seeing the instructions for the fan, I can't be any more specific. It would seem odd to have four terminals, unless the fan has both a high and low speed.

i have to say you obviously know your stuff.just to clarify the fan as you quite rightly stated has terminals N,L,LT,Lh,Ll. it has high and low speed. i wanted the fan to be switchable from a ceiling pull switch i will try the method you suggest and report back, once again your advice is appreciated. the fan entrance is above the shower in the ceiling. the fanmotor is ten feet away inside the loft.

 

[ban-all-sheds]

Why did you buy a fan with two speeds and timed overrun features when you have no intention of wiring it up so that it will be able to perform the features you paid for?

 

[ricicle]

Nuke or nurse, nurse or nuke...

 

[benitezhastogo]

Why did you buy a fan with two speeds and timed overrun features when you have no intention of wiring it up so that it will be able to perform the features you paid for?

well the fan is now wired with 3 core+e the terminals in the fan are:-
L,N,LT,Lh,LL. i have black cable from LT going to L1 in the pull switch, the brown is in L on the fan, blue is in N on the fan., a link is in place from LT to LL for the slow speed as per instructions! from the fan i have black in L1 on the pull switch, from the light (rose) i have three core now. black from three 3 core into comm on the switch, brown from rose linked to brown from the fan. neutral from the rose linked to neutral from the fan earths are linked in the pull switch terminal. CAN anyone advise the correct links as this fan still does not operate! i have the 2330 qualification i have the 17th edition but i have very little experience and can not for the life of me get a job working with an electrician ! should have stayed as a bus driver. please help!!!

 

[electronicsuk]

well the fan is now wired with 3 core+e the terminals in the fan are:-
L,N,LT,Lh,LL. i have black cable from LT going to L1 in the pull switch, the brown is in L on the fan, blue is in N on the fan., a link is in place from LT to LL for the slow speed as per instructions! from the fan i have black in L1 on the pull switch, from the light (rose) i have three core now. black from three 3 core into comm on the switch, brown from rose linked to brown from the fan. neutral from the rose linked to neutral from the fan earths are linked in the pull switch terminal.

I'm finding it hard to understand how you've tried to wire this. However, from what you've said, the best I can make out so far is this:

[code:1]
Fan: Switch: Rose:
L------[brown]-----O------[brown]----- BROWN?
N------[blue]------O------[blue]------ NEUTRAL?
---LT-----[black]---L1/COM---[black]----- ?
| LH
---LL

Earthing omitted for clarity
[/code:1]

First thing of note is that, unless you've used blue sleeving, the colours in your wire sound a bit odd. Are you using 4-core flex or something?

Second, it would seem very odd that the manufacturer's instructions recommend linking LT and LL to control the speed. If that's the case, what happens when the LT terminal doesn't have any voltage applied? The fan would most likely not run, meaning the timer run-on wouldn't work either.

So, firstly, I think you should remove the link between LT and LL, and instead, link the LL and L terminals.

Secondly, you need to look at the wiring between the rose and the switch. You don't seem to mention what happens with the black wire along the entire length of its run, but it's irrelevant, as you only need 3 core + earth between the switch and fan and not between the switch and rose.

As you've already changed all the wiring to 3c+e, I'd suggest you completely disconnect the black at both the rose and switch. Pick up a permanent live at the rose on the brown, and neutral on the blue. [Not to teach you to suck eggs, but the brown flex to the lampholder is NOT permanent live, so this isn't just necessarily a case of finding another brown wire and linking to it.]

At the switch, link both blue wires together in a terminal block, such that the neutral wiring is continuous right the way from the rose until it reaches the N terminal on the fan.

Brown (permanent live) from the ceiling rose should go to the COM terminal on the switch. Also in the COM terminal should be the brown wire from the L terminal of the fan.

Black from the fan's LT terminal should go to L1 on the switch, and should be marked with brown tape or sleeving at both ends to indicate the presence of a switched live.

All earth wires should be sleeved green/yellow, assuming you aren't using flex, and then be continuous throughout the run between the ceiling rose and fan. If there is an earth terminal at the switch, they should also be connected there. As the earth connection doesn't appear to be necessary for the fan itself, you should safely isolate it in an extra terminal block or similar at the fan.

If you follow the above instructions, the fan should run when the switch is on, and then continue to run for the preset timed period after the switch has been turned off.

As has already been pointed out, this is notifiable work on account of being in a bathroom.

 

[benitezhastogo]

well the fan is now wired with 3 core+e the terminals in the fan are:-
L,N,LT,Lh,LL. i have black cable from LT going to L1 in the pull switch, the brown is in L on the fan, blue is in N on the fan., a link is in place from LT to LL for the slow speed as per instructions! from the fan i have black in L1 on the pull switch, from the light (rose) i have three core now. black from three 3 core into comm on the switch, brown from rose linked to brown from the fan. neutral from the rose linked to neutral from the fan earths are linked in the pull switch terminal.

I'm finding it hard to understand how you've tried to wire this. However, from what you've said, the best I can make out so far is this:

[code:1]
Fan: Switch: Rose:
L------[brown]-----O------[brown]----- BROWN?
N------[blue]------O------[blue]------ NEUTRAL?
---LT-----[black]---L1/COM---[black]----- ?
| LH
---LL

Earthing omitted for clarity
[/code:1]

First thing of note is that, unless you've used blue sleeving, the colours in your wire sound a bit odd. Are you using 4-core flex or something?

Second, it would seem very odd that the manufacturer's instructions recommend linking LT and LL to control the speed. If that's the case, what happens when the LT terminal doesn't have any voltage applied? The fan would most likely not run, meaning the timer run-on wouldn't work either.

So, firstly, I think you should remove the link between LT and LL, and instead, link the LL and L terminals.

Secondly, you need to look at the wiring between the rose and the switch. You don't seem to mention what happens with the black wire along the entire length of its run, but it's irrelevant, as you only need 3 core + earth between the switch and fan and not between the switch and rose.

As you've already changed all the wiring to 3c+e, I'd suggest you completely disconnect the black at both the rose and switch. Pick up a permanent live at the rose on the brown, and neutral on the blue. [Not to teach you to suck eggs, but the brown flex to the lampholder is NOT permanent live, so this isn't just necessarily a case of finding another brown wire and linking to it.]

At the switch, link both blue wires together in a terminal block, such that the neutral wiring is continuous right the way from the rose until it reaches the N terminal on the fan.

Brown (permanent live) from the ceiling rose should go to the COM terminal on the switch. Also in the COM terminal should be the brown wire from the L terminal of the fan.

Black from the fan's LT terminal should go to L1 on the switch, and should be marked with brown tape or sleeving at both ends to indicate the presence of a switched live.

All earth wires should be sleeved green/yellow, assuming you aren't using flex, and then be continuous throughout the run between the ceiling rose and fan. If there is an earth terminal at the switch, they should also be connected there. As the earth connection doesn't appear to be necessary for the fan itself, you should safely isolate it in an extra terminal block or similar at the fan.

If you follow the above instructions, the fan should run when the switch is on, and then continue to run for the preset timed period after the switch has been turned off.

As has already been pointed out, this is notifiable work on account of being in a bathroom.

well i followed your advice i did indeed have 4 core flex! i now have the loop live to the comm then on to the L in fan, LT black from the fan to L1or L2 of switch removed black from rose to switch linked neutrals and after all that, it still does not work! now it appears the bloody fan is faulty unbelievable. i have had to order a new fan, fingers crossed guys, and thanks for your time.
just to clarify, notifyable means i have to do what now ( first time)

 

[ban-all-sheds]

just to clarify, notifyable means i have to do what now ( first time)

//www.diynot.com/wiki/electrics:part-p

 

[electronicsuk]

well i followed your advice i did indeed have 4 core flex! i now have the loop live to the comm then on to the L in fan, LT black from the fan to L1or L2 of switch removed black from rose to switch linked neutrals and after all that, it still does not work! now it appears the bloody fan is faulty unbelievable. i have had to order a new fan, fingers crossed guys, and thanks for your time.

Did you remember to link L and LL at the fan?