bathroom light flashes on when timed fan ends

[joeblogged]

Was passing the bathroom in my parents' new but 25yr old place when I noticed the bathroom light flash on and off just as the timed extractor fan shut off.

Tested again. Pulled the pull cord switch. Light comes on fan comes on. Then pull the chord, light goes off, fan stays on. OK so far. Then just as timed fan stops, the ceiling light flashes quickly on and off.

The ceiling mounted pull switch doesnt include a fan isolator.

There is no other fan isolator switch.

Is this normal? Is it something to worry about?

thanks.

 

[ColJack]

backfeed? capacitor discgarging?

 

[Taylortwocities]

Is the bathroom lamp a low energy type?

 

[joeblogged]

Yes. it has two low energy compact fluorescent bulbs in it.

 

[PrinceofDarkness]

This condition isn't anything to 'worry about', unless you find it irrirtating.

It's commonly found on 2-way lighting circuits with cfl lamps and is due to a natural induced charge from one conductor to another.

This can also happen with that combination that you have, of a 3-core cable feed to a timed fan with cfl lamps. Once the timer has switched off it leaves the permanent live to 'influence' the switched live with its induced charge, resulting in that flickering effect.

This induced charge is so slight that it would't have the 'real' power to affect a gls lamp.




Lucia.

 

[Taylortwocities]

You will probably find that one of the cables in the bathroom lighting circuit does not have its cpc connected to earth.