Replace old shower room fan

[lizzy2mellow]

Hi I am trying to replace an old fan, not sure when it was fitted. There were four wires in it, 1red, 1blue, 1yellow and 1bare copper. My new fan has only got 2 holes for wires and says constant live and the other is for nutral. So I am guessing its already earthed? Now I take it the live is red but not sure what the nutral one is?
Any advice would be great.
Thanks Lizzy

 

[riveralt]

Your old fan probably was a timer model hence the three core and earth at the terminal block marked L, SL, N and possibly earth.
Did you make a note of which colour core went with which terminal block?

Your new model appears to be a standard non timer model which requires just SL and N. You could alway exchange it for a timer model.

You don't say how your old model receives its power. Is it through a pull switch linked to a Fused connection unit and/or three pole isolator?

With the non timed model you need to isolate the L (permanent live) at the extractor fan. This could be achieved by tracing the three core back to the pull switch or whatever wiring system you have and disconnecting it leaving just the SL, N and earth active.

Whether you or an electrician does this for you will depend on your level of confidence of dealing with and understanding electrical circuits.

Just make sure you isolate the circuit and test that it is isolated before you start making changes.

 

[PrenticeBoyofDerry]

Your old fan would have had four terminals for switched live, permanent live,
neutral and earth.
The unit you have bought does not, it is likely it is double insulated should be this mark on it

Untitled

• PrenticeBoyofDerry
• 25 Feb 2011
• 14

Which means it requires no earth connection, so that is best sleeved with green/yellow pvc sleeve and terminated in to a separate connection block. Do not snip or cut off, as it may be need in the future and it also gives a good reference point for testing.
You then need to identify which core is perm live and which is switch live and which is neutral, if correctly wired originally the blue should be neutral.
But your original fan sounds like it could have been connected across the bathroom light and operated at the same time, is there an isolator in place?

 

[lizzy2mellow]

Hi, my fan has its own switch. Outside the shower room door I have 2 switches, 1 is for the light and the other is the fan.
How do I find out which colour is switch live and which is live?
I did take a photo of how the old fan was wired up but as I said the new one is totally different. All the wires go into a thick greay sleeve that goes into the wall. Thanks

 

[riveralt]

Hi, my fan has its own switch. Outside the shower room door I have 2 switches, 1 is for the light and the other is the fan.

Okay that may make it a little easier to do the next bit. But you will need to do a bit of investigating.

How do I find out which colour is switch live and which is live?
I did take a photo of how the old fan was wired up but as I said the new one is totally different. All the wires go into a thick greay sleeve that goes into the wall. Thanks

Both fans will have a L (maybe just the timer model), N, E SL (switch live) marked at the fans terminal strip.
If the old fan worked properly then you should be able to id which colour conductor goes where.(Photograph of the old fan terminations would be helpful).
If the power to the fan is directly from the wall switch then you will need to identify the SL and the Neutral - they are the two cables you need.

If that proves impossible and in any case you will need to open up the wall switch to identify how the switch has been wired. (Photograph the inside of the switch)
and if the switch is a double gang model the id which one is the shower fan switch).
There are numerous ways to wire the switch so it would be useless to try and guess at this point.