Extractor fan to timer type

[Daljit68]

Hi

I’m thinking of changing an extractor fan (in a WC) to one with a run on/timer. The current set up doesn’t have an isolator, and wiring runs from the light bulb to the fan, which is sited in the ceiling about 18” away. The fan is vented through a flat roof above.

Now, I realise that i’ll need a permanent live and to fit an isolator switch. I’m thinking of doing this:
- to leave existing wiring as is, and take a live feed from a lighting circuit junction box in the attic;
- to install an isolator switch in the permanent feed run, ie in the attic.

I’d rather not have to channel into walls to run a new 3 core cable.

Thanks

 

[Leesparkykent]

Hi

I’m thinking of changing an extractor fan (in a WC) to one with a run on/timer. The current set up doesn’t have an isolator, and wiring runs from the light bulb to the fan, which is sited in the ceiling about 18” away. The fan is vented through a flat roof above.

Now, I realise that i’ll need a permanent live and to fit an isolator switch. I’m thinking of doing this:
- to leave existing wiring as is, and take a live feed from a lighting circuit junction box in the attic;
- to install an isolator switch in the permanent feed run, ie in the attic.

I’d rather not have to channel into walls to run a new 3 core cable.

Thanks

Sound like a rubbish plan.

 

[Daljit68]

Sound like a rubbish plan.

Why would that be?

 

[Spoon]

Do you not think it would be a good idea to isolate the 'switch live' and 'neutral' as well?

 

[Charlie_]

The fan is in a flat roof.
You are going to take a feed to it from the attic?

 

[mhar]

You need to check the instructions for this new fan, a lot require a 3 Amp fuse fitting

 

[telectrix]

or give this guy a job.

 

[Wilko]

Hi - just so you know - new regulations from January mean that changing the wiring on a circuit with lights will require an RCD be fitted, if it’s not already. And depending on details, a building works notification (Part P) might also be required as you are doing electrical work in a bathroom. An Electrician can help you with both of these aspects, as well as testing the completed works are safe, just saying .

 

[HappyHippyDad]

That really doesn't sound good at all Daljit, also dangerous because:

1. You could be taking the permanent live (PL) from a different circuit.
2. You will only be isolating the PL not the switch live, so if you do use the isolator switch (i use the term lightly) you would still have a live fan when the light switch was on. Someone who moves in after you could well get an electric shock as they would never suspect that it had been wired so badly.

I realise you are probably trying to safe some money but you really should get an electrician to do this work.

 

[Daljit68]

Hi - just so you know - new regulations from January mean that changing the wiring on a circuit with lights will require an RCD be fitted, if it’s not already. And depending on details, a building works notification (Part P) might also be required as you are doing electrical work in a bathroom. An Electrician can help you with both of these aspects, as well as testing the completed works are safe, just saying .

Hi, WC so no special regs

 

[Daljit68]

Do you not think it would be a good idea to isolate the 'switch live' and 'neutral' as well?

Surely anyone looking to service the fan will know it only operates when the light is switched on...

 

[Daljit68]

That really doesn't sound good at all Daljit, also dangerous because:

1. You could be taking the permanent live (PL) from a different circuit.
2. You will only be isolating the PL not the switch live, so if you do use the isolator switch (i use the term lightly) you would still have a live fan when the light switch was on. Someone who moves in after you could well get an electric shock as they would never suspect that it had been wired so badly.

I realise you are probably trying to safe some money but you really should get an electrician to do this work.

Thanks for considered comment! It’s less about saving cash, it is a simple job but just don’t like the idea of channelling into walls.

 

[Daljit68]

Hi - just so you know - new regulations from January mean that changing the wiring on a circuit with lights will require an RCD be fitted, if it’s not already. And depending on details, a building works notification (Part P) might also be required as you are doing electrical work in a bathroom. An Electrician can help you with both of these aspects, as well as testing the completed works are safe, just saying .

It’s a WC

 

[Charlie_]

Surely anyone looking to service the fan will know it only operates when the light is switched on...

I thought you also wanted it to work whilst the light was off?

 

[Daljit68]

or give this guy a job.
View attachment 49903

Couldn’t do worse than a scouser in my experience

 

[Daljit68]

The fan is in a flat roof.
You are going to take a feed to it from the attic?

You never seen hooses with pitched roofs to the front and flat at the back???

 

[Charlie_]

Couldn’t do worse than a scouser in my experience

The guy in the picture could well be a scouser

 

[Charlie_]

You never seen hooses with pitched roofs to the front and flat at the back???

So you are planning on taking a feed from the pitched roof at the front round to the flat roof at the back?

 

[Charlie_]

I would just change the light fitting to a sensor type.. pir or mw

 

[Spoon]

Surely anyone looking to service the fan will know it only operates when the light is switched on...

I’m thinking of changing an extractor fan (in a WC) to one with a run on/timer.

Hi mate. The fan will require a 'permanent live' as well as a 'switch live'. Both will need isolation, as well as the 'neutral'.
Have a look at the manual for the fan you are thinking of getting. This should tell you how to wired it.
What fan are you thinking of getting?

 

[Tony Reidy]

Thanks for considered comment! It’s less about saving cash, it is a simple job but just don’t like the idea of channelling into walls.

Why do you need to channel into the wall if all the wiring is in the flat roof

 

[Daljit68]

Hi mate. The fan will require a 'permanent live' as well as a 'switch live'. Both will need isolation, as well as the 'neutral'.
Have a look at the manual for the fan you are thinking of getting. This should tell you how to wired it.
What fan are you thinking of getting?

An Envirovent SilentT 100.

Now thinking I could run wires from lightbulb (which run direct to CU (in WC) via switch) and a permanent live from lightning circuit in attic to an isolator switch located in ceiling, adjacent to fan.

 

[telectrix]

Couldn’t do worse than a scouser in my experience

these are real fans.

better than bloody bagpipes

 

[Spoon]

As @Tony Reidy asked above, "Why do you need to channel into the wall if all the wiring is in the flat roof "??

 

[Wilko]

An Envirovent SilentT 100.

These fans are ok, got one in my bathroom .

 

[Daljit68]

As @Tony Reidy asked above, "Why do you need to channel into the wall if all the wiring is in the flat roof "??

Single wire runs to switch in WC then up wall into flat roof void, then out at light socket. Linked from there to existing (non-timer) fan.

 

[telectrix]

why not just leave the light on for 20 minutes? otherwise it's not essential as in a bathroom extracting steam, only fart gas. leave for the benefit of next user.

 

[Spoon]

Single wire runs to switch in WC then up wall into flat roof void, then out at light socket. Linked from there to existing (non-timer) fan.

So there is a switch live wire going to the switch from the light?
There should be a 'permanent live', 'switch live' & 'neutral' at the light then. Can you not tap of these?
Does your CU have an RCD?

 

[Andy78]

This seems to be following a familiar pattern.
DIYer asks for advice
Forum says no don't do that it would be wrong and possibly dangerous
DIYer says no it won't

From here it usually goes one of two ways. DIYer sees sense and employs the services of an electrician to protect their own safety and that of their family and property.
Or the forum end up being tarred as elitist scum whose trade is a doddle and we are only withholding information as we are rip off merchants.

I'm on the edge of my seat.

 

[telectrix]

This seems to be following a familiar pattern.
DIYer asks for advice
Forum says no don't do that it would be wrong and possibly dangerous
DIYer says no it won't

From here it usually goes one of two ways. DIYer sees sense and employs the services of an electrician to protect their own safety and that of their family and property.
Or the forum end up being tarred as elitist scum whose trade is a doddle and we are only withholding information as we are rip off merchants.

I'm on the edge of my seat.

well, it's only 2 wires 3 wires, 4 wires. oh bugger, it's on fire.

 

[Daljit68]

So there is a switch live wire going to the switch from the light?
There should be a 'permanent live', 'switch live' & 'neutral' at the light then. Can you not tap of these?
Does your CU have an RCD?

Yes, CU is split rcd, with single 2.5mm T&E cable running (embedded) to wall switch (1m away) then (embedded) to roof void. If this was a 3 core wire instead of T&E I wouldn’t be posting on here ie I wouldn’t have a problem!

So I have Switch L and N. I’ll connect these to a fan isolator switch fixed into ceiling. Then run permanent live from lighting junction box in attic to same switch. That way, single switch will isolate for servicing, complying with regs.

 

[Daljit68]

This seems to be following a familiar pattern.
DIYer asks for advice
Forum says no don't do that it would be wrong and possibly dangerous
DIYer says no it won't

From here it usually goes one of two ways. DIYer sees sense and employs the services of an electrician to protect their own safety and that of their family and property.
Or the forum end up being tarred as elitist scum whose trade is a doddle and we are only withholding information as we are rip off merchants.

I'm on the edge of my seat.

Naval gaze all you want. Some of us have got work to do.

 

[Daljit68]

these are real fans.

better than bloody bagpipes

Sets us up nicely for a Scotland v England wold cup qualifier this pm!
Ps you’re nothing without Andy Robertson!

 

[Daljit68]

Yes, CU is split rcd, with single 2.5mm T&E cable running (embedded) to wall switch (1m away) then (embedded) to roof void. If this was a 3 core wire instead of T&E I wouldn’t be posting on here ie I wouldn’t have a problem!

So I have Switch L and N. I’ll connect these to a fan isolator switch fixed into ceiling. Then run permanent live from lighting junction box in attic to same switch. That way, single switch will isolate for servicing, complying with regs.

Forgot to say, cable connected to 6amp circuit breaker in CU.

 

[Spoon]

Yes, CU is split rcd, with single 2.5mm T&E cable running (embedded) to wall switch (1m away) then (embedded) to roof void. If this was a 3 core wire instead of T&E I wouldn’t be posting on here ie I wouldn’t have a problem!

Oh. I get it now mate.

So I have Switch L and N. I’ll connect these to a fan isolator switch fixed into ceiling. Then run permanent live from lighting junction box in attic to same switch. That way, single switch will isolate for servicing, complying with regs.

But then you will have a fan circuit fed from two different breakers.

 

[Daljit68]

Oh. I get it now mate.



But then you will have a fan circuit fed from two different breakers.

Hallelujah! The lighting junction box in atTic is on a circuit that’s connected to same breaker in CU! So I won’t be linking different circuits!

If this now complies with all regs, then saves me a hell of a lot of hassle and mess of ripping into walls.

 

[telectrix]

red to red, black to black, blue to bits.

 

[Daljit68]

red to red, black to black, blue to bits.

If you had the tech knowledge you’d explain why it might blue to bits. But you don’t so you make crap gags.

 

[telectrix]

If you had the tech knowledge you’d explain why it might blue to bits. But you don’t so you make crap gags.

can't take a joke? seems you have the sense of humour of a potato.

 

[Daljit68]

can't take a joke? seems you have the sense of humour of a potato.

Look for advice mate. Read the above and see the -------s I’ve had.

 

[Pete999]

If you had the tech knowledge you’d explain why it might blue to bits. But you don’t so you make crap gags.

Go for the Juggler Tel

 

[Andy78]

If you had the tech knowledge you’d explain why it might blue to bits. But you don’t so you make crap gags.

If you had the technical knowledge to do this job it'd be done.

 

[Spoon]

Hallelujah! The lighting junction box in atTic is on a circuit that’s connected to same breaker in CU! So I won’t be linking different circuits!

If this now complies with all regs, then saves me a hell of a lot of hassle and mess of ripping into walls.

We got there in the end mate. That's why we have to ask questions, to get the full picture.

 

[Charlie_]

We all wondered why you needed a fan with a run on timer just for a WC.
I now see why, the amount of .... you come out with, it’s gonna be knackered out in no time!

 

[Leesparkykent]

Thread closed. The OP clearly doesn’t have a scooby doo what he’s up to....Talking about light sockets???? The sensible thing to do, would be to employ an electrician.