Bathroom fan wiring problem

[lakud]

Extractor fan fitted to new extension. Manrose 100mm/timer. To come on with lights. Cabled through isolator.

Problem: Fan does not work. With light off - permanent live (L2) is live, switched live (L1) is dead. With light on - permanent live is dead, switched live is live.?? I can fix it by taking a permanent feed from elsewhere but would feel safer knowing how this can occur in the first place

Fan is ok Suggestions welcome.

 

[Taylortwocities]

Two questions:

1. Has it ever worked (if not, then get the electrician back who fitted it)

2. How are you testing these connections as live, or not? With a test meter? with neon screwdriver? And with reference to what, the neutral?

 

[ban-all-sheds]

3. Why not get back the electrician who installed it in the first place?

 

[riveralt]

Assuming it is a three pole isolator (live, switch live and neutral) positioned between the lamp and the fan and that the switch is a normal rocker with live from the ceiling rose (light) and switch live back to the ceiling rose lamp.
You should have a three core and earth running from the ceiling rose to the isolator -
with brown from the permanent live,
grey (brown sleeve) from your switch live at the ceiling rose and
black (blue sleeve) from the neutral at the ceiling rose.
Also run the earth through as well.

Then continue the same colour scheme from the isolator to the appropriate terminals at the fan.

 

[Taylortwocities]

I'm guessing neutral problem, either missing or swopped with another conductor.

 

[lakud]

Thanks for your reply.

The problem is as handed over. Junction box not accessible.

I am testing with a meter in reference to neutral. As suggested I am interested in how this effect has been achieved in the first place.

 

[pjcomp]

Sounds like the light switch is a two-way switch (pull or rocker) and the fan's permanent live is in the secondary terminal. With the light switch "off" the power goes from the live incomer out the permanent live. With the switch "on" the power goes from incomer to the switched live but deads off the second terminal.

If this interpretation is correct, the permanent live needs to be moved to the "common" terminal in the switch.

PJ

 

[Taylortwocities]

The problem is as handed over. Junction box not accessible.

.

Does that mean the problem was handed over to you by whoever built the extension?

What junction box? A junction box should not be needed, if there is one, with screwed terminals then is must be accessible....

OK, so you are testing at the fan, yes?

Do you see the same voltages at the isolation switch?
If yopu are going to take a permanent live from anywhere, it must be a live from the same lighting circuit, nowhere else.

 

[lakud]

There are three rooms in the lean-to extension (12 degree slope roof - my daughters) each with multiple downlighters hence junction boxes in the ceiling as opposed to loop-in ceiling roses. Not readily accessible but can be got at in extremis. As she does not want the timer I was intending to put a link between switched live and permanent live anyway but wary until I understand the present oddity. Voltage are the same at fan and isolator

(LATER) Have visited and tried the link - which threw the RCBO for the circuit. Light switch is 1-way.