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However after leaving at night the customer has rang to say the light that operates when switched on with the fan, has a constant dim light. Bulb is a small 3watt led. It must be getting some slight back feed, only when the fan iso is on. Has anyone experienced this before, greatful for any input. Thanks
The fan complicates things a bit - the extra load on the SL line should if anything help reduce the problem. So perhaps there's some coupling between the perm L and SL lines due to the wiring layout changes, Or as you say perhaps a little current flowing back from the fan's electronics from L to SL.
Not sure how best to resolve it. If the fan is isolated its completely fine.
If that works, invest in a small capacitor and put it in shunt with the lamp in the back of the holder or in a small box.
(you can buy one at exorbitant price with a label on it) or without once you know the value needed for far less..
If the fan is isolated its completely fine.Is there a decent length of cable between the isolator and fan?
Is it 3-core + earth?
If so, are the L and SL in 3-core both to the same side of the c.p.c.? (with perhaps N on the other)
If all of the above then perhaps swapping the cores around so L and SL are on opposite sides might help... (or might not..) Should be a relatively cheap experiment either way.
I could revert back to a low voltage fan as the transformer will stop any back feed
You may be lucky if the over-run timer is not the same design in the controller for the ELV one and for some reason has less cross-talk, but it is not the transformer or the fan voltage that is helping you.
Assuming I have read the sequence correctly
new timer 2 takes mains switched and steady, and applies that mains direct to a 230v fan, for a preset over-run period after lights out.
The key is not the transformer vs mains fan, rather that timer 1 loads the switched live so its voltage falls cleanly to zero when the light switch is off, while timer 2 leaks a few micro amps from the steady live to the switched line and so to the light, relying on the light to pull it all the way to 0V, but being LED it gives off a noticeable light even at this low current.
It may be that timer and transformer are integrated and cannot be separated, but if they can you could save yourself the aggro of removing the new mains fan, that is all.
How do you mean as intended ?
A small convenient night light.
That is really step 1.