(Probably a simple) wiring question

When your meter leads aren't connected to anything you get a reading of 0v so the switch live could be open circuit.
 
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Ok, so assuming it's an open circuit from switched live to neutral but 240V from perm live to neutral, it must be a problem in the switched live part of the fan, no? I'll try switched live vs earth tomorrow and see where that gets me!

I'll also draw a diagram tomorrow of how I've wired it up, but in the mean time... :confused:
 
Multimeter says there's 240V across both the permanent live and neutral, and the switched live and neutral, at the three pole isolator. However the same test at the fan terminals gives 240V between permanent live and neutral, but zero V between switched live and neutral (with the lights on).
Therefore the SL conductor is not continuous.

Ok, so assuming it's an open circuit from switched live to neutral
Not open circuit - just no voltage on SL terminal.

but 240V from perm live to neutral, it must be a problem in the switched live part of the fan, no?
No - it's a problem with the SL conductor.

I'll try switched live vs earth tomorrow and see where that gets me!
Ok. If you have reported correctly that will be 0V.

I'll also draw a diagram tomorrow of how I've wired it up, but in the mean time... :confused:
There isn't much to draw.

Measure continuity between SL at isolator and SL at fan.



To verify the fan works -
Remove SL from fan.
Insert short wire in PL terminal with PL conductor and connect other end of short wire to SL terminal.
Fan should run continuously.
 
Wire from isolator to fan must be continuous surely, or there wouldn't be a potential difference between the perm live and the neutral at the fan?
That would confirm that those two cables where continuous, so perm live and neutral are okay.
There was 0V between the perm live and the switched live at the fan
Which does not really tell us anything as you would expect it to be anyway.
which is weird because that would suggest both were at 240V.
In theory you are testing the same phase against each other, so you would expect a zero reading if open or closed.
which if true would suggest a problem with the neutral
No it wouldn't you first test between line and neutral confirms you have both of them in place.
yet if the neutral was the problem I wouldn't have 240V between perm live and neutral!
The neutral seems fine, it was not used when testing across the line and switch line, so that is irrelevant but was tested between line and neutral where results were satisfactory.

Prentice, do you mean the isolator switch? The isolator was closed when I was testing, as in it was on. When I tested I turned on the light switch and the isolator.
I meant was the light in operation at the time of testing, so that the switch live was actually energized (providing continuity is satisfactory).
This one has me stumped. Must be a broken fan!
If you have not yet confirmed continuity of all conductors this would be hard to assume.
Try testing between neutral and CPC for 0V, I have seen no record of this yet, lets amke sure you are actually have the conductors identified correctly, as I think polarity needs to be confirmed, another reason for the CPC to be present.

Then I suggest you go back to basics and test all the conductors continuity, this is when the CPC/earth comes in handy again, but evidence so far is suggesting that your switch live is either loose, insulation nipped up by terminal grub screw, broken or not connected.

If you would like to upload pictures/photo and a wee diagram of the way you have installed, it may help.
 
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Morning :D. Thanks for your help so far.

I've just hooked up the perm live terminal to the switched live on the fan:

psbY0mC.jpg

(I'll terminate the earth properly once I've got the fan working).

240V present across live and neutral but still no action from the fan :(, which means the switched live isn't the problem because it's now out of the equation.

Continuity test (with circuit shut off at consumer unit) showed infinite resistance between both lives and neutral at fan terminal. Not sure I did this right though, I'll test vs. earth when I get back up in the loft.

Here are a few more pics...

View showing entire arrangement:

MqAmHkl.jpg


Original wiring to fan:

ssMZxTi.jpg


Close up of junction box:

WWYZkOo.jpg
 
Picture of any isolators.
For continuity, you would need to link the two conductors being tested together, then test across the open end.
So you are using black core as neutral, grey switch live, brown perm live.
Test across junction box all terminals, including earth/CPC and post the results. Also the conductors require sleeving to identify them, once the issue has been resolved.
 
Here's the isolator:

gFtq7ci.jpg


So I went back up into the loft, still convinced from my findings that the fan was at fault. I had a good look around the fan wiring, and I found something odd. It's a goodun. See if you can spot if from this photo!

FpLtVkR.jpg


So yes, I wasted 4 hours of my weekend trying to find fault with my wiring, when it was the fan after all. All good fun! I wonder if god was punishing me for not buying a Vent Axia :LOL:. Although to be fair, it's possible that I knocked it out during installation.

Anyway it's all fixed and working perfectly now. Massive thank you for all your help. So relieved it's finished. My jobs always seem to turn from what should be basic into 8 hour marathons.

Here's some pics of the extract and exhaust vent. As you can see I've got a hole to fill as it hit a noggin, and some scraping to do on the ceiling where the moisture has lifted the paint. Hopefully this is a thing of the past with my new 250m^3 per hour beast!

The fan is really quite quiet by the way. Quieter by far that the cheapo axial in our ensuite. Mounting it on a gardener's kneeling pad seemed to help.

Zs9B7EP.jpg


hDT7BFs.jpg
 
Well at least that has solved a problem!
There should be lesson to be learnt here, most probably several.
But if you had done the basic dead test whilst installing, then checked life polarity when going live. You would have at least have confirmed that the installation was functioning as expected.
Then if the fan did not work, it could have only been the fan, probably adding 20-30mins of your time, which would have made the diagnosis probably simple!, instead of 4hrs of your time plus the time spent by the helpful posters on here.
Don't forget that the cables need IDing. Live conductors sleeved brown, neutral conductors sleeved blue, bare CPCs sleeved green and yellow and a sticker at the board informing two versions of BS7671 colours are present.
As stated previously at least a minor works cert should be issued.
https://www.elecsa.co.uk/Documents/.../BS7671-Amd1-Minor-Works-Certificate-(1).aspx
 
Thanks guys, lots of lessons learned indeed. One of which was: don't assume you've made a mistake when you're confident the wiring you've done is correct! ;)
 
I don't know how to do a basic dead test or to check live polarity, truth be told. I may have inadvertently done both of those things at some point after the installation, but I don't know what they are.

If you have any links that would explain them so I can do some reading for next time, that would be much appreciated.
 

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