[noshed]

My kitchen extractor fan has packed up (probably due to the amount of grease caking it). I have got it off the wall and exposed the wiring without incident. I'm just going to get a new one the same and install it into the same 150mm hole. What occured to me during this slightly feverish bout of DIY is - is it safe to work on a spur as long as it is switched off at the fused switch? Or should I switch off the entire mains circuit, causing anguish to flatmates using computers?
The other thing is, there are 4 wires coming from the mains - earth, yellow, red and blue. The earth is not connected to the fan but the yellow one goes to the yellow one on the fan, red to red and blue to black. Fairly logical I would have thought and I was going to connect the new one in the same way. But there is a bit of red tape on the yellow mains wire and a bit of black tape on the blue one. I was going to ignore this as some sort of playful electrician's thing, do I need to worry?
Has anyone any thoughts?

[mumofstig]

IMO you should isolate the circuit, you'll probably pop the circuit breaker with an earthing fault when you do the rewiring anyway, and it won't take long to do will it?
If I remember my wiring correctly the red tape is to mark the switched live from the fused switch and the black marks the neutral, nothing to worry about.
Just connect it exactly the same in the new fan...good luck

[8doubles]

Just switch off the spur and remove the fuse, you will need power in the kitchen for a cup of tea!

[noshed]

Oh that's great. Now I just have to find a suitable fan...

[Trillium]

Can I recommend that you look for what that has removable grease catchers that can be washed out often? I find those help me a lot even though I don't cook much with grease/oil/whatever, but the stuff still seems to accumulate.

[noshed]

You'd think they would design them exactly like that but most of them seem to have the electrics near the front so it's hard to clean them properly.

[Gwiz]

That does seem to be bizarre design feature.
We've had to fit two now, and we don't use oil/grease hardly ever. You do wonder where it all comes from......

[noshed]

Arghh - had to get a different fan. A Vent Axia one which I hope will be better. But it seems to want you just to connect 2 wires - N and L. What colours are those? I presume that is line and neutral - so would that be the yellow one with the red tape on (line) and neutral being the blue one with the black tape on?
There's another option to connect 3 wires: LS, L and N if you have a pull cord, which I haven't.
Any thoughts?
I suppose I should study the old one more carefully and look for helpful markings.

[Lardman]

L & N is Live and Neutral

Depending on the age of your wiring and who did it .

Live : Red or Brown
Neutral : Black or Blue

And looking at your OP you have 4 core control flex rather than T&E.

LS is Live Switched.

Im not comfortable giving advice on without seeing it as getting it wrong would be .... well not good !

But If I was doing it, this is what I would do.

ISOLATE the circuit at the fuse box. No messing about.

Check the control switch face plate to see how its wired.

Red is probably : Live
Blue is probably : Neutral
Yellow is probably : Switched Live

Pull cord / wall plate switch same principle.

This sort of work is to the best of my knowledge also subject to part P.

[noshed]

Thanks Lardman. I am super cautious with leccy so I might get my handy friend to come round and have a look if it doesn't make obvious sense.
Thanks again

[hamstergbert]

Thanks Lardman. I am super cautious with leccy so I might get my handy friend to come round and have a look if it doesn't make obvious sense.
Thanks again

Also make sure every single one of your flatmates know what you are doing so one doesn't wander along to investigate and think to themselves "Hello - this breaker seems to have tripped.   Wonder why.  Anyway, I'll just reset it and...."

[noshed]

Good advice

[noshed]

At long last it is installed - took about 10 mins after all that faffing about. Thanks everyone for your advice. I'm still alive to tell the tale. Wot you said wuz right.