Wiring confusion at junction box - Vent Axia VASF100T

[meales]

Hi
I hope someone could help explain in simple terms what I am struggling to understand.

I had an extractor fitted about 5 years ago but speed was always slow (dimmer light switch fitted). I replaced the GU10 50W with LED 5W and they always stayed lit even when switched off...I think even the fan stayed on dead slow! So I fitted the 50W GU10 again.

Eventually the extractor died and I have replaced it with a new VASF100T. With the dimmer light level up to max, the speed slowed down to a virtual stop. With the light level down, the speed was at high. I replaced the dimmer switch with a standard light switch and hey presto...the fan doesn't operate at all. However, the light level is up high!

I've taken photos of what I found in the loft space and uploaded it in the PDF file attached....in the vain hope that clever people can educate me, please!!

many thanks in anticipation

 

[EFLImpudence]

It's difficult to make out where all the wires go, but -

assuming your description is correct, this is where they should go:

All earth wires (not shown) should be connected together and, of course to earth.

 

[Iggifer]

How have you connected things at the fan end?

The key principle of carrying out electric works is never assume, and you seem to have a lot of assumptions in your diagram.

Also, never, ever cut off a CPC because it's not needed at the other end, each point of fixed wiring must have a CPC, so you need to re-terminate that fan cable, connect the earth, and make it safe the other end.

You have WAAAAY too much copper showing in the switch, I know the MK terminals are really small, but either trim it back so no copper is showing or bend it over so again, no copper is showing.

And generally, fans are wired:

Grey - Neutral
Black - Switched Live
Brown - Perm Live

(Some people swap brown and black, but grey is the key one to get right)

 

[chivers67]

What an awful junction box! There are bare earth conductors inside it too. It's very difficult to see which terminal the assumed light red conductor is terminated here but you shouldn't run a fan on as dimmer switch!

 

[EFLImpudence]

And generally, fans are wired:

Grey - Neutral
Black - Switched Live
Brown - Perm Live

That does not appear to be the case here.

(... but grey is the key one to get right)

That is simply not true.

We've had this before.
If ALL the other neutrals are black, I would continue to use black as neutral.

 

[Iggifer]

Well the NICEICs advice (yes, I am aware they don't write the regs, but try telling them that) is to use grey as Neutral regardless of current installation

 

[EFLImpudence]

Q.E.D.

 

[JohnW2]

... but you shouldn't run a fan on as dimmer switch!

Whilst, for obvious reasons, one should not try to run a non-timer fan from the output of a dimmer switch, I would have expected it to work OK with a timer fan. The fan is then supplied from the permanent L, and I would imagine that the output of the dimmer switch would be able to trigger the timer.

Kind Regards, John

 

[deadshort]

Well the NICEICs advice (yes, I am aware they don't write the regs, but try telling them that) is to use grey as Neutral regardless of current installation

How bloody daft is that

DS

 

[Taylortwocities]

To be fair to them. The guidance from IET on colours at the time of the launch of harmonised wiring colours was exactly that for 3 core applications
Red = brown
Blue = grey
Yellow = black
They wanted installers to forget that neutral was ever a black colour.

 

[EFLImpudence]

To be fair to them. The guidance from IET on colours at the time of the launch of harmonised wiring colours was exactly that for 3 core applications
Red = brown
Blue = grey
Yellow = black

Isn't that just the conversion of three-phase colours
L1 Red = brown
L2 Yellow = black
L3 Blue = grey

They wanted installers to forget that neutral was ever a black colour.

If true, an utterly futile wish when daily working on (not very) old installations.

 

[Taylortwocities]

Can anyone understand the logic of those guys in the marble edifice.

 

[securespark]

The NIC?

 

[Taylortwocities]

IET. NICEIC are a charity, they don't do marble

 

[meales]

I'm really sorry for not responding sooner...kids school hols has been a total distraction!

Thank you all for your responses. I haven't revisited the loft and the fan is still connected as previously...and not operating. I've connected the fan wiring, as the photo shows and I hope it is correct......?

Comments about the copper wiring noted, should I trim down and reconnect?

I'm not sure why the really long earth lead, which exits the junction box, has been snipped. I remember an electrician re-earthed the house in 2007 when I moved in. It could be that the electrician who did the wiring for the new extension last year snipped it for some reason...he never said anything to me. Would I have to trace the other end of the snipped earth and join them? Or is there a reason he would have cut it?

Many thanks for your expert views

Mark