changing a bathroom extract easy???? NOT

[DirtyDog368]

HELLO ALL,

i attended a customer with a reported faulty bathroom fan. It was the timer variety with a three pin connection.
I checked the pins and found there to be 240v present so i determined that the fan must be shot. 30mins later i get back with the new fan and connect up but it did not work.

the fan i baught was a ASX100T from greenwood air managment, (a good fan)
there is a three pole isolator switch on the wall outside
and of course the bathroom light switch

at the isolator there are three cables grey, black and brown
now here's the funny thing
when the light switch is closed and the lights are on, the black wire from isolator to the fan is the ony live cable
when the light swtich is open and the lights are off, the brown wire from the isolator to the fan is the only live cable.

from my understanding of the wiring diagram, in order for the ASX100T to work i need a switched live and a constant live.

So am i missing something?
Anyhoo i did try to access cables to rewire accordingly but they are hidden behind a suspended ceiling and access can only be gained by removing this ceiling which is not a real option as of yet.

!- any idea why the circuit is wired up two switch over live from one core to another - could it be a fault or was it supposed to be like that?
2- what options do i have to get the new fan SAFELY working.....

i have included the wiring instructons for the newASX100T fan (1st column 2nd row).....

thanks guys for all your help

DD368

 

[Dave_]

I agree with Richard!

When you described the fault it sounds like the two live cores (brown/black) are connected to the strappers of a two switch. Check the bathroom light switch! One should be on the common..

 

[needasparks]

If there was no neutral turning the light on would alternate potential between lives if using it to test with.

 

[DirtyDog368]

Gentlemen, i just like to mention this.
this site is of great value and in this day and age with hardly any apprentiships and few engineers willing to take on a young spark under their wing it is even more valued. ALl your opionion and even the occasioanl rant is taken with my appreciation and thanks.

Now with regards to my competance : I feel that I am in my right mind and have the technical knowledge and know how with respect to domestic electrics and hold certificates coming out of my wazzu...BUT I also appreciated that the real world is far removed from the class room. So in order to avoid smart arse responses I try my best to word my questions correctly......hence my first question was like so

1- any idea why the circuit is wired up two switch over live from one core to another - could it be a fault or was it supposed to be like that?

this question is simplly asking weather or not there is a manufacturer out there that makes a fan which operates on two live and a neutral. L1 and L2 and N and if when the lights are on L1 is the ONLY live and when the lights are off L2 is the only live..which is what is happening.

From what i have gathered here, thanks to the invaluable responses, there is no such a fan and therefore I will embark upon fault finding and start ripping up wires confidently knowing that i am doing the right thing.....

NOW isnt that a smart approach?

As tothe comment regarding testing between live and neutral.......that was uneccesary, but i suppose you have to let off steam somewhere.:elvis:

again many thanks to all those lekkies that take the time and effort to respond constructively....

 

[GLENNSPARK]

If there was no neutral turning the light on would alternate potential between lives if using it to test with.

hence the momentary change in light levels when switching a incorrectly wired 2 way......

 

[vernam616]

Gentlemen, i just like to mention this.
this site is of great value and in this day and age with hardly any apprentiships and few engineers willing to take on a young spark under their wing it is even more valued. ALl your opionion and even the occasioanl rant is taken with my appreciation and thanks.

Now with regards to my competance : I feel that I am in my right mind and have the technical knowledge and know how with respect to domestic electrics and hold certificates coming out of my wazzu...BUT I also appreciated that the real world is far removed from the class room. So in order to avoid smart arse responses I try my best to word my questions correctly......hence my first question was like so

1- any idea why the circuit is wired up two switch over live from one core to another - could it be a fault or was it supposed to be like that?

this question is simplly asking weather or not there is a manufacturer out there that makes a fan which operates on two live and a neutral. L1 and L2 and N and if when the lights are on L1 is the ONLY live and when the lights are off L2 is the only live..which is what is happening.

From what i have gathered here, thanks to the invaluable responses, there is no such a fan and therefore I will embark upon fault finding and start ripping up wires confidently knowing that i am doing the right thing.....

NOW isnt that a smart approach?

As tothe comment regarding testing between live and neutral.......that was uneccesary, but i suppose you have to let off steam somewhere.:elvis:

again many thanks to all those lekkies that take the time and effort to respond constructively....

Any competant electrician would look for the fault without the need of asking others, like i said if you were an apprentice/diyer , id have had more of a positive input

Heres an easier approach, DISCONNECT THE FAN AND TEST AT ALL POINTS, TAKE HEED OF THE 2 WAY SWITCH RESPONSE AS IT SOUNDS LIKE A GOOD ONE

 

[needasparks]

I think also a clue is in the callout. Was the fan working at some point as this would rule out problems with miss-wired switches.

 

[Groucho Mace]

Gentlemen, if we have guys using different coloured cores for lives and switch lives and even neutrals how can we be expected to understand WTF someone has done. Niceic printed cable colours along with many other publications. Old colours were RYB - live/switch live/neutral and new colours BR/BL/Gry so brown = Live: Black = switch Live (sleeved brown) : Grey = Neutral ( sleeved blue) Simples!

 

[HandySparks]

Gentlemen, if we have guys using different coloured cores for lives and switch lives and even neutrals how can we be expected to understand WTF someone has done. Niceic printed cable colours along with many other publications. Old colours were RYB - live/switch live/neutral and new colours BR/BL/Gry so brown = Live: Black = switch Live (sleeved brown) : Grey = Neutral ( sleeved blue) Simples!

That's all well and good if you're signed up with NIC, but wouldn't it be better if the use of specific coloured cores in various typical situations was explicitly recommended in BS7671 or even the On Site Guide (I'm sure someone will correct me if it is). Although, of course, you use sleeving I really think that they missed a trick when amending the regs.

 

[CrazyScozzese]

They should have made them all grey or whatever, preferably a colour not in the old scheme so you knew they were new, and you have to sleeve them with a uniquie colour that identifies them as specifically L1,2,3, switched live, N, etc. That way, there is no confusion. All you have to do them is worry about who sleeved them, but a quick check would verify what they purported to be. Which we all do anyway.

And if they were not sleeved, it would force you to check them and not trust what they purported to be too.

Having colours that can be used for various uses, is just loose regulation, especially when they went to all the trouble of changing.

 

[GLENNSPARK]

They should have made them all grey or whatever, preferably a colour not in the old scheme so you knew they were new, and you have to sleeve them with a uniquie colour that identifies them as specifically L1,2,3, switched live, N, etc. That way, there is no confusion. All you have to do them is worry about who sleeved them, but a quick check would verify what they purported to be. Which we all do anyway.

And if they were not sleeved, it would force you to check them and not trust what they purported to be too.

Having colours that can be used for various uses, is just loose regulation, especially when they went to all the trouble of changing.

need colour id....otherwise you`d spend more time bellin em..lol....

 

[Amp David]

In all honesty it doesn't get much simpler than a bathroom fan with an over run.

Just step back, have a brew then look at it again. I'm sure it'll all become clear