Installing in-line extractor fan (with timer)

[ban-all-sheds]

I am only measuring it with my tape. I bought the cable at B & Q as lighting circuit cable. It's about half the thickness of the cable I got for installing a fused spur to a power socket, and about a third of the thickness of the cable to my electric Hob.

OK - it's the right size cable.

The single red wire I added from the light switch to the isolater, and on to the fan I taped to the other cable to keep them all together and labeled them as such, should someone else need them in future, and used the red one as it connects to the red at the light switch

For the third time, that is wrong, and not allowed. You may not have a single-insulated cable running anywhere except within a containment system. Taping it to the other cable will not do - you must remove it and replace it with a sheathed cable.

You've got some of that - why did you make more work for yourself by pulling it apart to make it unsafe?

Use twin and earth from the switch to the isolator. Either terminate the unused core in choc-block at each end or sleeve it G/Y at each end and connect it to the earth.

Then use 3-core & earth from the isolator to the fan.

OR - as sparkwright says, if your lighting circuit loops through the light fitting, or a nearby JB, you'll have permanent and switched live and neutral in one place and you can use 3C+E from there to the isolator.

The earth lead was connected to the earth in the light switch, but there is no connection for it in the isolator, or the fan.

Doesn't matter - you must still maintain earth continuity in all of the cables. If the box that the isolator is in has no earth terminal then join the earths inside it with a piece of choc-block.

At the fan terminate the earth with the same - don't just cut it back.

Incidently, if your wondering why I just don't get an electrician to do this, the last one I had in, several years ago was installing my gas boiler. The plumber removed the old back boiler from the fireplace, installed connecting pipes and installed the a gas fire in front of it without tightening the pipes. the water soaked through both sides of the wall and the plaster fell off both walls. The electrician wired the heating thermostat to the motorised valve for the hot water, and the heating thermostat to the hot water valve. The hot water cylinder nearly exploded before I came home and worked out what was wrong.

And you think they're all like that?

 

[ban-all-sheds]

I ... stripped out the red lead out of another length for the third lead from the light switch to the fan switch through the isolator.

I bought the cable at B & Q as lighting circuit cable.

B&Q are still selling red/black cable?

 

[jakobyte]

I ... stripped out the red lead out of another length for the third lead from the light switch to the fan switch through the isolator.

I bought the cable at B & Q as lighting circuit cable.

B&Q are still selling red/black cable?

OK I got it. The single red wire is not right. I like the sound of the 3 core + earth right from the junction + switch to the fan, through the isolator, but I've never seen this before as Iv'e never had anything that requires it, and I can't say I've seen that type of cable at B & Q. I'll have a look though.
Regarding tradesmen. No, I don't think they're not all like that, but how do you no the good ones. My neighbour has had a plumber, who I was told was one of the best, installing a new boiler, and has just arrived back for the 7th or 8th time in the last 5 months.

 

[jakobyte]

I ... stripped out the red lead out of another length for the third lead from the light switch to the fan switch through the isolator.

I bought the cable at B & Q as lighting circuit cable.

B&Q are still selling red/black cable?

OK I got it. The single red wire is not right. I like the sound of the 3 core + earth right from the junction + switch to the fan, through the isolator, but I've never seen this before as i've never had anything that requires it, and I can't say I've seen that type of cable at B & Q. I'll have a look though.
Regarding tradesmen. No, I don't think they're not all like that, but how do you no the good ones. My neighbour has had a plumber, who I was told was one of the best, installing a new boiler, and has just arrived back for the 7th or 8th time in the last 5 months.

B & Q have 2 types. first is 3core + earth, the earth being a bare single 6mm2 wire and the other three, again a single 1mm wire but insulated, which I assume is the kind you recommend.
The other type is 4 core where each wire is 1mm2 strands, where one of them is the earth.
Either way, I need to find an electrical supplier who sell by the meter, as B & Q only sell in minimum 10m rolls.
I'm still going to have to seal off the earth at the fan though as there are only 3 connects at the end of the circuit board. the fan and the casing are all plastic, the only other metal in there are the motor parts themselves.

 

[sparkwright]

The 3 core+earth is probably the better option.

Fewer places are doing it by the metre, save your petrol and get the 10 m roll!

At the fan, sleeve the bare earth and terminate it into a 5 amp connector block.

 

[jakobyte]

The 3 core+earth is probably the better option.

Fewer places are doing it by the metre, save your petrol and get the 10 m roll!

At the fan, sleeve the bare earth and terminate it into a 5 amp connector block.

That could well be right, but I have a shed full of odd bits of wire, paint, wood, nails, screws, you mane it, because I had to by more than I needed, and I better keep the rest in case I need it.
I need lest than a metre because I put in a 4-way junction at the pull light switch when I installed a mirror light in the bathroom years ago.
A neighbour has suggested instead of venting the fan out through the soffit, vent it into the header tank in the loft an use it as a condenser, the way it works in a tumble drier.
Would that work.

 

[Paul-man]

The 3 core+earth is probably the better option.

Fewer places are doing it by the metre, save your petrol and get the 10 m roll!

At the fan, sleeve the bare earth and terminate it into a 5 amp connector block.

I got my 3 core and earth by the metre from TLC Direct... look them up, they have everything there is probably one near you. (that's was aimed at the OP- not you spark- i'm sure you've heard of them!)