Wiring in new extractor fan

[NBee]

Hi everyone. I've just installed a new Fantronix TT100T extractor fan, which is an inline type, in the loft. Everything's done, I (just) need to get it wired up. I'm pretty sure I'll be calling someone in to do this, but all the same I'm curious and like to understand what's going on, and would be grateful if you could comment/confirm my assumptions below.

The wiring diagram can be seen on Page 6 (fig 16,17,18) here: http://www.fantronix.com/acatalog/tt_user.pdf

My bathroom light runs on the main lighting ring from the circuit board, with a 6A fuse, and is operated from a pull cord also in the bathroom. This will operate the fan, which has a run-on timer.

- I'm pretty sure that this means the fan needs a 4-core cable with live (brown), switched live (black) and blue (neutral). No earth necessary.

- Am I correct in thinking that this cable is fed down from the loft and wired directly into the terminals of the bathroom light switch? Or would the light fitting be used, rather than the switch?

- Or is there a way it can be taken from the cable in the loft using a junction box, without actually touching the light switch, or light fitting, terminals at all?


That's it for now..!

 

[Taylortwocities]

It depends on how your lighting is wired. The cable to the fan will need a permanent live, a switched live a neutral and an earth.
The cable (4-core as you say) will come from the place where all of the above come together. This can be at the switch, or at the light or in an additional JB, it depends.

An isolation switch is also useful. For an in-line fan, i would put it next to the fan in the loft, otherwise you'll have to turn off the power to the upstairs lights (inluding the loft lights!) should you need to work on the fan.

 

[NBee]

Thanks. Ah yes, forgot to mention the isolator - I've already put the casing in place attached to a joist near the fan where I know the cable will be run.

So basically I need to study the current layout a bit more closely, and take it from there.

 

[Taylortwocities]

A diagram of how to wire it can be found in the WIKI, assuming the loop-in is at the light.

 

[NBee]

That's a really useful link, many thanks.

So we're talking about a light fitting with 12 (twelve!) wires in it. I'm going to have to replace the existing one as it's old and fiddly and I can remember from a few years ago that I already had no space in there. One of the new ones with 9 connector points looks like the part to get.

One further question for now - do you know how the wiring to the fan itself in your wiki diagram compares to that in the manual (below)? The manual only shows a L and N wire to the fan, but then an LT wire appears.

 

[Taylortwocities]

I am not familiar with your fan, but my guess is that the termianl marked "SL" on the WIKI diagram (switched live) is the LT terminal on your timer fan.