Bathroom extractor fan... dodgy wire?

[benroles]

Hi All,

I am doing some DIY on my bathroom... firstly I have replaced the main light with a nice 3-spot halogen (all working) and am now on to the final job - replaing the extractor fan.

The original DID work many moons ago but just started hanging off the wall, making a god-awful noise and then generally died. As such, I know at some point the connections must have work.

However... move on and I have now removed the fan and am left with 4 wires:

Red - perm. live
Blue - neutral
Yellow - switched live
Green / yellow - earth

1) Is the above summary of what the wires are correct?

2) If so, I wire up my new 230v extractor fan (with terminals N, L, L1 - no need for earth according to manufacturer). I turn the light siwtch on and... nothing.

Now I next start to think maybe a wire has become loose somewhere. So I got a circuit tester and held the probes against:

blue / red - nothing
blue / yellow -nothing
red / yellow - connection (although this test makes no sense in my mind)

Now.. I did do the tests above with the consumer unit completely off so no power is going to anywhere in my flat... but I assume that's what you have to do unless you want to fry?!

So... am I doing something wrong or has a connection come loose somewhere? If it's the latter, would I be right in thinking all three of the wires to the fan probably come from my ceiling rose? If so I might check there to see if something has come unconnected.

Your thoughts, comments and warnings of "stop.. you are about to kill yourself" most welcome.

Thanks,
Ben.

 

[ColJack]

try blue to earth with the tester.. it should read something close to continuity.. ( as neutral and earth are connected at some point along the journey to your house.. )

 

[benroles]

Thanks ColJack - I will try that and report back. Is what I am trying to do / my understanding of the wires etc. looking correct then? I did do quite a bit of research to understand what I am doing and am a bit miffed it didn't succeed!

Is it right to think the extractor wires all come off the light-point (whether live, switched live or whatever?)

B.

 

[ban-all-sheds]

Red - perm. live
Blue - neutral
Yellow - switched live
Green / yellow - earth

1) Is the above summary of what the wires are correct?

It might be....

2) If so, I wire up my new 230v extractor fan (with terminals N, L, L1 - no need for earth according to manufacturer). I turn the light siwtch on and... nothing.

...or it might not be.

Now I next start to think maybe a wire has become loose somewhere. So I got a circuit tester and held the probes against:

What kind of circuit tester?

What were you measuring between the probes?

would I be right in thinking all three of the wires to the fan probably come from my ceiling rose?

You might be.

If so I might check there to see if something has come unconnected.

Good idea - if the cable does come from there you'll be able to see which core is L/SL/N....

No 3-pole isolation switch by the sounds of it?

 

[benroles]

Hi - thanks for your response... take your point on the colouring of the wires. In terms of the testing device I reference, it's a rapitest little battery powered device that has 3 settings - AC power, DC battery and circuit test. I had it on this third setting. Is this what I need?

Going to look now at the wires in the ceiling rose.

And no... there doesn't appear to be an isolation switch. Something I was slightly concerned about, particularly as it's a flat with a no-window bathroom. Shouldn't one have been put in when it was built - it's only mid-90s??

Thanks,
B.

 

[benroles]

Yay! All sorted. I checked the ceiling rose and a rogue neutral wire wasn't plumbed in to anything. Connected that back up in the ceiling rose, refitted the fan and all working. Fires up on light switch going on and timer does it's stuff after power down at switch.

Only concern... it's definitely NOT got an isolation switch. Since i've really just reused old wiring (albeit with a few fixes along the route) I don't really want to mess around any more (since it's working). This is particularly true since I live in a flat and all this wiring is near completely impossible to get to (even in the bathroom it's all behind tiles).

Should one have been fitted when the flat was built? Since I've just put the flat back to the same state it was in as new (i.e. without one) is there a requirement to fit one? Thoughts and comments appreciated.

And thanks for all your help.

B.

 

[ban-all-sheds]

There should be one, as without you cannot do any work on the fan - it will always have a live feed to it.