Extractor fan activated by other lights in the house

[ahlondon]

My bathroom extractor fan is switching on when lights for other rooms are switched on. The extractor is on a switched live setting with an isolator switch.

It happened after a couple of light fittings and a light switch were changed, so could someone advise if it's something as simple as the live and neutral in the light or the L1/COM in the switch being connected the wrong way round?

Note, when the isolator switch is OFF, the connected light fitting LEDs have a slight glow suggesting there is live leakage from somewhere. Could the wiring between the extractor, light and isolator be wrong?

 

[EFLImpudence]

It happened after a couple of light fittings and a light switch were changed,

Bit of a clue: did it all work properly before?

so could someone advise if it's something as simple as the live and neutral in the light or the L1/COM in the switch being connected the wrong way round?

No.

Note, when the isolator switch is OFF, the connected light fitting LEDs have a slight glow suggesting there is live leakage from somewhere.

Did they not do that before?

Could the wiring between the extractor, light and isolator be wrong?

It is certainly wrong somewhere.

 

[ericmark]

The problem with LED lamps is there are many ways to feed the LED elements with the current required to make them light, so working out what have been done wrong is not easy.

The fan does not need much to triggure it.

But the dim glow points to either an electronic switch or a line wire being mistaken for a neutral.

What have you got to test with, I find non contact voltage testers handy to work out line and neutral, but seems clear an error has been made.

 

[opps]

I am not am electrician.......

But I have seen LEDs that glow slightly when the light switch is in the off position. I guess that it is an induction thing. Hopefully someone more knowledgeable than me will comment.

 

[ahlondon]

The problem with LED lamps is there are many ways to feed the LED elements with the current required to make them light, so working out what have been done wrong is not easy.

The fan does not need much to triggure it.

But the dim glow points to either an electronic switch or a line wire being mistaken for a neutral.

What have you got to test with, I find non contact voltage testers handy to work out line and neutral, but seems clear an error has been made.

When you say electronic switch, is that a light switch? If it is a line wire being mistaken for a neutral, would that limited to the light fitting associated with the fan or the whole lighting circuit it is part of? Thanks

 

[bernardgreen]

Capacitive coupling between Live and Switched Live in the cable to the switch creates a high impedance "by-pass" circuit across the switch. This "by_pass" allows a very small amount of power to reach the lamp. LED lamps glow on this very small amount of power.

 

[ahlondon]

Capacitive coupling between Live and Switched Live in the cable to the switch creates a high impedance "by-pass" circuit across the switch. This "by_pass" allows a very small amount of power to reach the lamp. LED lamps glow on this very small amount of power.

Previously one cheap LED lamp was being lit so I put a better one in - that would explain that issue I guess.

 

[ahlondon]

More help please! I looked at swapping the fan and check the wires were not live after switching off the isolator but ALL THREE are live? The tester glows stronger with the isolator switched on, but there is clearly still current going through the constantly. Could the fan and light connection be mis-wired or something elsewhere on the circuit be mixed up?

 

[HERTS P&D]

Time to call a spark in.

Andy

 

[terryplumb]

You should call in an electrician

 

[opps]

More help please! I looked at swapping the fan and check the wires were not live after switching off the isolator but ALL THREE are live? The tester glows stronger with the isolator switched on, but there is clearly still current going through the constantly. Could the fan and light connection be mis-wired or something elsewhere on the circuit be mixed up?

It sounds like your tester is picking up an inductive load. Do you not have multi-meter that you can use?

I once purchased a cheap voltage pen. It was overly sensitive. It would glow and bleep if I ran it over screws in plasterboard.

 

[ahlondon]

Solved! While I don't deny there might still be a mis-wire somewhere, I changed the "Blauberg" branded fan with a Manrose one and the issue stopped presenting itself.