Replacing Extractor fan

[Benjis_dad]

First question - is a straight replacement in a kitchen ok, or do I legally have to have a part P cert?

Replacing a Silavent 150mm 6" Axial Fan Pull Cord SDF150PB with a Silavent SDF150HTB.

The mains wiring is Brown, Black, Grey and plain earth. Black seems to be carrying the current and this (I guess) is because there is a wall switch.

The fan has Live (red), Neutral (blue black) & Switched Live (yellow).

Any guidance on what goes where is appreciated - the fan is on a RCD if that makes any difference.

 

[sparkwright]

Red black and grey are unusual for the MAINS wiring.

Sure you've got that right?

How was the old fan wired?

 

[Benjis_dad]

You're right, BROWN, black grey and bare - 3 core & earth.

 

[Taylortwocities]

OK, so

How was the old fan wired?

EDIT, yes you can do the change.
EDIT2. There is no such thing as a Part P certificate.

 

[ban-all-sheds]

There is no such thing as a Part P certificate.

Benjis_dad - FYI, Part P is one of the parts of the Building Regulations.

It is not a qualification, it is not a certificate, it is not a restriction on who can do what where, it is simply a requirement to make reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury.

 

[Benjis_dad]

So far as how the fan was previously wired - embarrassed to say, no idea. The old one was removed pre-decorating and before the new one arrived.

Thanks for comments re Part P. Thought for electrics in kitchens and bathrooms some works had to be carried out by qualified electricians - my bad.

I would have thought Brown Mains to Neutral on the fan. Black Mains to Live on the fan, with a loop to the switch live.

When I do that, RCD flips.

On the fused switch on the wall, I have 2 cables coming in.

L1 has 2 x Blue
L2 has 2 x Brown
Common has 1 x black

the fuse part of the switch seems to have the other black.

 

[Taylortwocities]

The rules for notification have changed over the years.
You will need a 2 probe voltage tester (NOT a neon screwdriver) or a multimeter To sort out which wire is which at the fan.
Do you have such a thing?

 

[Taylortwocities]

More...
You said that you are

Replacing a Silavent 150mm 6" Axial Fan Pull Cord SDF150PB with a Silavent SDF150HTB.

The old fan is a non-timer pull cord fan and the new one is a timer fan.
How do you know that the wiring you have is even capable of connecting to a timer fan?
The old fan only needed a permanent live and neutral, the new one also will need a switched live.

I would have thought Brown Mains to Neutral on the fan. Black Mains to Live on the fan, with a loop to the switch live.

Are you nuts or do you really have no idea about electrical wiring. With electrics never ever assume anything.
it is not a guessing game and if its not done right you can damage the fan - you may have already done that - or yourself, .

You need a proper test device to find out what each wire does. In the UK the wiring colour convention is that brown is live (what made you think it went to the neutral?)
Then you are left with grey and black. One of those will be the neutral and it could be either. The other may be the switched live, but the old fan did not need a switched live, so it may not even be connected to anything.

Do not disturb, remove or swop round any wires in switches, lights etc or you will be in even deeper doo doo than you already are.

 

[securespark]

I would have thought Brown Mains to Neutral on the fan. Black Mains to Live on the fan, with a loop to the switch live.

Black and brown are usually used as line conductors.

On the fused switch on the wall, I have 2 cables coming in.

L1 has 2 x Blue
L2 has 2 x Brown
Common has 1 x black

"Fused" switches (if you mean fused connection unit) do not have a common terminal.

Maybe some pictures would help!

 

[Benjis_dad]

Obviously from comments above, I may have to accept this is beyond me and call an electrician.

However, I will pop some photos on in an hour or so, just in case that makes it clearer.

So far, on my neon screwdriver, I only have a 'reading' on the black mains lead.

Equipment wise, I do not possess a 2 probe voltage tester - are they expensive? Argos / B&Q / Maplin sell them?

Like to think I am not nuts - there are things I know lots about and others I don't, which is why I'm on here asking questions.

Ta

 

[Taylortwocities]

You can get a cheap one for about £6 at Maplin.
Take your neon screwdriver with you and drop it in a waste bin on your way .those things are no good for anything. Not even for driving a screw.

 

[Benjis_dad]

Will get the voltage tester tomorrow. Hope you find this clarifies things -

 

[Taylortwocities]

Hard to see, as your pix seem to be pixelated,
What is that switch? What has it to do with the fan?

At the fan there is a cable that has brown, grey and black wires. That cable does not come from the switch that you have pictured. So it must come from somewhere else.

Looking at wires and guessing is not going to help. You need a test meter to determine which wire is which.

 

[Benjis_dad]

The switch shown is the one on the opposite wall that controls power to the fan - well for the last 12 months, when I have flicked it, the fan becomes live. I understand your confusion over the colours but, switch on, fan on.

For un-pixelated pic, see link.

Now, about this tester I need to obtain . . .

This sort of thing http://www.maplin.co.uk/p/3-in-1-voltage-tester-rm68y# ?

 

[Iggifer]

It looks like, and that's as far as I'll commit to:

An FCU has been used from the ring to supply the fan.

Grey = Neutral
Black = SL or Permanent Live
Brown = Either not used, or supplied as a Permanent Live from elsewhere as I can't see a third brown in that FCU.