LED light in bathroom flashes when extractor fan TP pole switch is closed.

[HappyHippyDad]

I have just fitted the manrose humidity/timer remote unit into a bathroom (see pic below)



When I switch the LED bathroom light off, it starts flashing. If I switch the TP switch for the extractor fan off it stops flashing. This only started happening when I introduced the humidity/timer remote unit.

I could understand if the LED light stayed on dimly, but why is it flashing? My idea was to fit a 230V snubber across L-N of the light, would this work? Is there a particular rated snubber that I need?

Could I just fit 2 x 160Kohm 1/4w (230V) resistors across L-N at the lamp?

Would these be suitable:

1. https://www.tlc-direct.co.uk/Produc...Vf7l0_PK95NUwqfCbCLK7uDq1xrzYX9EaArUHEALw_wcB

2. https://www.ebay.co.uk/itm/LED-Snub...ED-Bulbs-STOPS-Nausea-Migraines-/324163668142

3. https://cpc.farnell.com/ampohm-woun...-100/contact-suppressor-0-1uf-100r/dp/FT00715

Cheers

 

[telectrix]

seems likely it's the fan controller causing the problem. snubber would be your first shot. maybe a comined R/C snubber.

 

[HappyHippyDad]

seems likely it's the fan controller causing the problem. snubber would be your first shot. maybe a comined R/C snubber.

Do you fit them as shown in my diagram Tel? I.e across line and neutral at the lamp? Any particular snubber you use?

 

[telectrix]

across L and N feeding lamp. various snubbers available. used a couple of these in the past:
https://www.ebay.co.uk/itm/0-1uF-10...243494?hash=item1cecd19926:g:fAMAAOSwpRRWnC90

 

[pc1966]

I would go with the CPC one myself, no metal tag to fix and they are generally light enough to sit in any back box or similar quite happily.

 

[telectrix]

onlyproblem with cpc is if that's all you need ( as in not part of a larger order) the postage is 10x the value of the item.

 

[pc1966]

Yes, that is a good point.

 

[Marvo]

Depending how the circuit is wired you could use a d/pole light switch and switch both the live and the neutral.

If you're really brave you could fit a 2-way light switch, put the switched live on the 'common' terminal, the live on one of the other terminals and an earth on the last terminal. The earth is functional as well as protective after all...

The emoji's seem to have disappeared so imagine the smiley one at the end of the last sentance or maybe the smiley one that's winking. Not sure if the UK regs will allow the second option but on the off-chance you can use it I'd suggest you leave a note in the switch box for the next sparky, it might save him soiling his underwear.

 

[Dartlec]

Depending how the circuit is wired you could use a d/pole light switch and switch both the live and the neutral.

If you're really brave you could fit a 2-way light switch, put the switched live on the 'common' terminal, the live on one of the other terminals and an earth on the last terminal. The earth is functional as well as protective after all...

The emoji's seem to have disappeared so imagine the smiley one at the end of the last sentance or maybe the smiley one that's winking. Not sure if the UK regs will allow the second option but on the off-chance you can use it I'd suggest you leave a note in the switch box for the next sparky, it might save him soiling his underwear.

Smileys still work if you use the shortcuts I believe - I'm sure the colon codes worked the other day, but seem not to now - but colon and then right bracket for smiley face, colon and P for tongue,,,

 

[HappyHippyDad]

Depending how the circuit is wired you could use a d/pole light switch and switch both the live and the neutral.

If you're really brave you could fit a 2-way light switch, put the switched live on the 'common' terminal, the live on one of the other terminals and an earth on the last terminal. The earth is functional as well as protective after all...

The emoji's seem to have disappeared so imagine the smiley one at the end of the last sentance or maybe the smiley one that's winking. Not sure if the UK regs will allow the second option but on the off-chance you can use it I'd suggest you leave a note in the switch box for the next sparky, it might save him soiling his underwear.

I've just been reading one of your past posts from a few years back Marvo, which said exactly the same thing with regards the earth. You got a minor telling off from @Lucien Nunes

 

[happysteve]

If you're really brave you could fit a 2-way light switch, put the switched live on the 'common' terminal, the live on one of the other terminals and an earth on the last terminal. The earth is functional as well as protective after all...

Won't that lead to a N-E resistance equal to the load being switched (when then switch is in the "off" position)? We tend to frown on such things (though it makes interesting fault-finding)...

 

[Lucien Nunes]

And could put 500V across the fan trigger input with an otherwise innocent-seeming L+N - E insulation test.

I could understand if the LED light stayed on dimly, but why is it flashing?

Other than cheap low-wattage ones that use a capacitive dropper, LED lamps have a switched-mode power supply as a driver. When stray capacitance in the wiring or a control device like your humidistat leaks a small current into the switched line, it passes through the rectifier and slowly charges up the reservoir capacitor in the driver until the voltage is high enough for the circuit to start up. It delivers a brief pulse of output to the LEDs, but in a few milliseconds the charge stored in the capacitor is used up and it shuts down. The capacitor begins to charge again...

 

[Pretty Mouth]

If you're really brave you could fit a 2-way light switch, put the switched live on the 'common' terminal, the live on one of the other terminals and an earth on the last terminal. The earth is functional as well as protective after all...

I suppose if the N was brought to the last terminal instead of the earth, that would equalise any potential across the lamp when switched off? Not sure it's a good idea/compliant though, something to do with switching neutrals

 

[pc1966]

I suppose if the N was brought to the last terminal instead of the earth, that would equalise any potential across the lamp when switched off? Not sure it's a good idea/compliant though, something to do with switching neutrals

Using a change-over switch to short out the lamp is perfectly OK as you are not switching the neutral, you are switching the live feed to the lamp (i.e. at no point would both lamp terminals be live due to an open on the neutral path).

But...I would worry about the next one changing the switch getting a nasty surprise as it is so common/normal to have unsleeved blue (or black) as the switched live to a light (not really neutral)!

 

[Marvo]

I've just been reading one of your past posts from a few years back Marvo, which said exactly the same thing with regards the earth. You got a minor telling off from @Lucien Nunes

Yeah, quite possibly and quite rightly so, hence the smileys. As mentioned by Pretty Mouth it would be a considerably more legitimate remedy if you used the neutral rather than the earth. Creating a path between neutral and earth, even a very resistance path, within an installation isn't a good idea for several reasons and it's forbidden in my local regs so I'm guessing it's also forbidden in the UK regs.