want to Understand Fan Wiring

[ste3g]

I have a new ceiling bathroom extractor fan which has 2 terminals. blue & Black. The house supply cable in the loft has 4 wires. Earth, brown, black and grey ( switched live presumably )

The light switch controls the fan and there is an isolator switch higher up on the wall.

Please can someone explain the wiring diagram because I wan’t to understand the circuit.
Many thanks.

( see attached pix )

 

[ProDave]

Convention is grey= neutral, brown= permanent live and black = switched L, but there are variations so you would normally check to confirm that.

In that case brown and E you safely terminate as they are not used. Black to the fan blue, and grey to the fan black

What's the red and black crimped together?

 

[ste3g]

Hi ProDave,
Thank you. You’re right. I checked the other fan in the other bathroom.
And I did what you said and it works perfectly. I safely terminated the live permanent brown. And put the black wire into the live blue of the fan. Grey wire to black neutral of the fan. I don’t know what that crimped bit is. The fan came like that.
Hit with your help I understand the wiring now.
I think the permanent live brown must be for thermostatic fans with an overrun. The one I bought is a simple fan.
All the switches work now and it hasn’t tripped! lol.
It’s really satisfying learning something.
Thanks for your help man.
I appreciate it.
Steve.
( photo is the previous fan )

 

[ProDave]

Thanks for letting us know. Your previous fan had an over tun timer so it would stay on for a few minutes after you turn the light off.

And well done for photographing the old wiring before disconnecting. All too often we have people who have disconnected, usually a light fitting, and then have a mass of different wiring and don't know how to re connect.

 

[SPECIAL LOCATION]

Hi ProDave,
Thank you. You’re right. I checked the other fan in the other bathroom.
And I did what you said and it works perfectly. I safely terminated the live permanent brown. And put the black wire into the live blue of the fan. Grey wire to black neutral of the fan. I don’t know what that crimped bit is. The fan came like that.
Hit with your help I understand the wiring now.
I think the permanent live brown must be for thermostatic fans with an overrun. The one I bought is a simple fan.
All the switches work now and it hasn’t tripped! lol.
It’s really satisfying learning something.
Thanks for your help man.
I appreciate it.
Steve.
( photo is the previous fan )

In wiring regulations Brown, Black and Grey are ALL colours to identify live conductors, and Blue is a neutral conductor.. (Green/Yellow is earth).
Where an insulated conductor is used for another function it should have sleeve or tape applied to identify the actual function.

e.g. it would have been good practice to put some coloured sleeve over the Black and Grey conductors to make identification less confusing.. So Black with some brown sleeve/tape and Grey with some blue sleeve/tape.