Axial Extractor fan with timer - 2 or 3 wires

[potterton678]

Evening
Looking to install an axial extractor in a vertical wall, next to the electric shower (that's Zone 1, I guess)
Fan can't be installed in the ceiling.

The light cable only has 2 wires in it (brown and blue iirc).

Does the extractor fan with the timer need more wires in the light cable or are 2 wires sufficient?

Would want the fan to operate independently (with a pull-cord switch inside the room to switch the fan on or off) of the light.

Your thoughts/experiences please.

PS _ Different question, why don't all electrical cables have 3 wires in domestic houses?

 

[chivers67]

You'll need a 3 core to supply a switched live and permanent live for run on. You could opt for an Extra low voltage / 12V for Zone1

 

[morqthana]

Does the extractor fan with the timer need more wires in the light cable or are 2 wires sufficient?

Yes and no.

However...

Would want the fan to operate independently (with a pull-cord switch inside the room to switch the fan on or off) of the light.

You'll be running a cable from that switch to the fan, so that one can be 3C+E. Bear in mind that you'll need a permanent live to supply that switch. What cables are at the light, and at the light switch?

PS _ Different question, why don't all electrical cables have 3 wires in domestic houses?

Because apart from timer fans and 2-way light switches, 2 cores (plus earth) are enough.

 

[morqthana]

You could opt for an Extra low voltage / 12V for Zone1

Still needs 3C+E to the 12V power supply.

 

[morqthana]

Dragon's Den moment:

On the face of it the power needed to keep a 12V fan motor running for 20 minutes or so is well within the capacity of a decent 12V lithium battery. I wonder if there'd be a market for a fan supply which could provide a timed overrun without needing a permanent live feed?

 

[potterton678]

What cables are at the light, and at the light switch?

What cables are at the light, and at the light switch?

For the light at the ceiling it's just 2 cables (brown and blue iirc).

Not sure at the switch.

But there is a pull chord (I assume it's an isolator for the electric shower) in the ceiling almost directly above the light switch.

 

[Murdochcat]

IIRC there are 12v fans that only need 2 core cable from the transformer to the fan unit