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

 

[telectrix]

generally, black will be perm. L. brown = switched L. grey ( which should be sleeved blue) = N. check at the 3 pole isolator. if not, swop black and brown.

 

[ipf]

Check the 3 core and earth terminals at origin and adjust accordingly.

 

[vernam616]

Why are we telling fellow electricians how to fault find?

Strange place this

 

[DirtyDog368]

everyone has to start somewhere .....;-)
(I hope your not saying you walked into your first job knowing it all)

 

[telectrix]

when i was young and green, wish i had had access to a forum like this one. nearest thing to a computer we had was a slide rule. all practical learning came from the older sparks.

 

[GLENNSPARK]

so you got 230V between what?...line-neutral.....or line-earth..or did you check both?

 

[needasparks]

When i went on a job for the first time i did not know everything, there are so many variants from manufactorers but i knew how to test for live, neutral and earth.

 

[Richard Burns]

Sounds like the bathroom light switch is a 2 way switch with the switched line to the fan on on L1 and permanent line to the fan on L2 whereas permanent line should be on C. However not having seen the situation I cannot be certain, but worth a look.

 

[GLENNSPARK]

i just thought that if you had only tested both line conductors to earth and got 230V between em.....then how would you know that your noutral was good......but yes.....perminant line=L1.....switched line=L2......

 

[jumpin jax]

Why are we telling fellow electricians how to fault find?

Strange place this

you can't win! either you are an electrician asking for advice and get slated or you're a DIYer asking for advice and get slated, so what is this forum for, chit chat and the price of cheese

 

[GLENNSPARK]

just noticed n all in the first post here that the black appears to have been used as one of the line conductors on this 3 core cable.....bad practice that is.....should be the neutral and sleaved blue as such ....the reason i say this is that on the old colours the black was the neutral...so theres a similarity there....it aint 3 phase where on the new colours the black is L2......

 

[Richard Burns]

The recommendation (that I do not agree with) is that grey is used as neutral as it is a neutral colour and steps well away from using black as neutral as it is no longer neutral but line in 3phase, as you say.
(I use black as neutral!)

 

[vernam616]

you can't win! either you are an electrician asking for advice and get slated or you're a DIYer asking for advice and get slated, so what is this forum for, chit chat and the price of cheese

Scenario:

Customer calls with above fault, you attend and scratch your head

Reply to customer " Erm well ive had a look and because i advertised as an electrician doesnt mean i am one, so im going to have a look on the net on my phone and wait for a answer, when i find it ill come and do the job, but you make sure you pay me the same money as a electrician "

Internet is partly to blame for the complete lack of incompetance in electricians today

i did not walk into the job knowing it all, infact nobody will ever know it all, we all learn everyday, however i did serve my time the old fashioned way, until you have served time and gained experience i suggest you dont advertise your self as a "electrician", how embarrassing to tell your customer, how much confidence do you think they would have in referring you to friends and relatives?


Had you come across and said you were a DIYer or apprentice, id do my best to try guide you, but seriously to advertise your services as a "electrician" then ask us on here how to find the fault is just madness, how the hell do you think we manage to do it? and whoever said faults were easy!?

 

[Adam W]

I use grey (sleeved) as neutral as recommended by NICEIC and black (sleeved) as common (live) in a switch, permanent live or L2, although that is a different argument.

In this situation I would have a look at how the 3 core is connected, ie in the light fitting or in the switch, and see if there is anything untoward.