Dimmer switch interference

I've got a wierd situation that I can't explain so I was wondering if anyone can help.

I recently replaced my living room light switch with a double dimmer (Varilight Vpro). I'm pretty certain all the wiring is correct, and the lights generally work as expected. However, I've noticed that occassionally when I switch lights OFF in other rooms (on the same lighting circuit) one or both of my living room lights switch off. If I then switch my living room lights off and then back on they work again.

I've double checked the wiring and all seems fine. On further inspection its only when I turn the bathroom or outisde light off that this happens - and both of these are CFL lights. I've put a multimeter on the terminals of the dimmer switch, and noticed that when these CFL lights are switched off I see a brief surge - up to about 400V. I'm wondering whether there is something odd going on to do with the CFL lights being an inductive load, and when I turn them off they are creating a brief surge which is triggering the dimmer switches overload protection???? But this might be total rubbish.

Both the CFL lights are going to be replaced at some point which I suspect will solve the issue, but I'm just slightly worried that as I can't explain what is happening then I also can't be sure it isn't dangerous.

Any advice or suggestions gratefully received!

Matt

Go for the simple option and replace the CFLs. Your problems could be down to the Vpros not liking the indicated 400v or (more likely imho) them registering the brief pulses as a control signal.

I have exactly this problem now, but with LED lamps, and replacement dimmers are on their way. This will be my 4th set of replacement V-Pro dimmers, so I think they are pretty **** tbh.

The last set went back because turning another light on sent them to full brightness - quite the opposite! And the previous 2 sets because they entered programming mode randomly, or increased brightness from turning on very, very, very slowly.

Luckily they have a 10yr warranty, but I won't be buying any more!

Thanks oldbutnotdead - I think you are right that I'm worrying too much!

Phatboy - good to know that it's not just me. I'm coming to the same conclusion about VPro - the lights take such a long time to come on that it's hard to work out which switch is which, and then you end up turning them off and then back on, and suddenly its gone into configuration mode. And that's when they are working properly! This is my second VPro after the first failed (admittedly becuase I put a bulb in that turned out to be non-dimmable, but I wouldn't expect it to break the dimmer)

I'm tempted to return the dimmer and try to get my money back and get a different one, and if it's still an issue replace the CFLs too.

Thanks so much to both of you for taking the time to reply.

Matt

Matthew1234 said:

Thanks oldbutnotdead - I think you are right that I'm worrying too much!

Phatboy - good to know that it's not just me. I'm coming to the same conclusion about VPro - the lights take such a long time to come on that it's hard to work out which switch is which, and then you end up turning them off and then back on, and suddenly its gone into configuration mode. And that's when they are working properly! This is my second VPro after the first failed (admittedly becuase I put a bulb in that turned out to be non-dimmable, but I wouldn't expect it to break the dimmer)

I'm tempted to return the dimmer and try to get my money back and get a different one, and if it's still an issue replace the CFLs too.

Thanks so much to both of you for taking the time to reply.

Matt

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I've also had a bad lamp blow a dimmer, it always went to full power after the failure. That was an LED lamp.

Very slow increase in brightness is apparently when it cannot detect the load type, so setting it to a drive mode manually may help.

I finally got around to moaning to TLC again about this, and they escalated to Varlight who said.....

Varilight said:

The dimmer modules are turning off when they detect a high inrush load coming in on the shared live. There was a change made to the software to increase the overload protection sensitivity for extra protection, so the dimmer are detecting a large surge of current from the high inrush load and turning off. There isn’t anything wrong with the extra sensitive ones as long as they aren’t being used in conjunction with fluorescent tubes, fans, or large LED circuits; they are actually a safer dimmer to have installed in most cases.

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Seems like a stupid change to me, but Varilight are going to send me some dimmers with 'modified' software to stop this issue.

Thanks phatboy for posting this - really useful info. I can't help feeling that they'll quietly reverse this change but they don't want to admit that they've messed it up! Not being to use it on the same circuit as a fan or CFL seems quite a big limitation to me - and certainly something that should have been mentioned in the specs!

I changed my dimmer for another one which was great until I changed the LED bulbs (flickering G9's - but that's a whole different story...) - and now the new dimmer doesn't work with the new bulbs! Perhaps I'll complain to Varilight and see if they can send me one with modified software too.

Thanks again for all your help - initially I thought I was going mad (and my wife thought that I couldn't do basic electrics...)

Matt

Matthew1234 said:

Thanks phatboy for posting this - really useful info. I can't help feeling that they'll quietly reverse this change but they don't want to admit that they've messed it up! Not being to use it on the same circuit as a fan or CFL seems quite a big limitation to me - and certainly something that should have been mentioned in the specs!

I changed my dimmer for another one which was great until I changed the LED bulbs (flickering G9's - but that's a whole different story...) - and now the new dimmer doesn't work with the new bulbs! Perhaps I'll complain to Varilight and see if they can send me one with modified software too.

Thanks again for all your help - initially I thought I was going mad (and my wife thought that I couldn't do basic electrics...)

Matt

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Haha yes, you're not going mad!

I discovered another issue with another dimmer today... a different lighting circuit. When I turn the fluorescent light in the loft off, the dimmer in the lounge goes off and comes back on again.

Unsure if I need to ask for more replacements, or just give in and buy another brand.....

It does not need to be a dimmer, I have Energenie MiHome wifi switches, with five fitted they seemed to have a life of there own, random turning off, I removed two so now only three fitted, and they work as they should, no problems.

I did not measure voltage, two separate lighting circuits, and SPD fitted in the consumer unit.

I love the remote control in bedroom to turn lights off from bed, but really don't need it in living and dinning rooms, and when dimming switches caused the bulbs to glow red, there was ambiance, but most LED lamps the colour does not change, so really no point dimming any more, looked at the colour changing bulbs, and with eight bulbs in the chandelier that gets rather expensive.

Been bitten with bulbs and claimed life, got 16 Philips golf ball CFL in last house 8 watt each for two rooms, claimed to last 10 years, after 1 year half had failed, also a LED fluorescent tube replacement, fluorescent with magnetic ballast lasted around 4 years a tube, the LED did not last 1 year. OK may be one off's, but they are expensive one off's, my fluorescent tube 18 watt top of stairs in a emergency light fitting so HF lasted 20 years and tended to be left on, fitted 1998 on it's second tube. Batteries now about US so lasts around 5 minutes with power cut. But lights in a bulb shape do not seem to last as long. So to buy bulbs that dim, seems too much of a risk, and may simply not last.

The old tungsten bulb was claimed to have a fuse built into bulb so if they failed with ionisation (big flash) it would blow that fuse not the main fuse, and lamp holders rated at 2 amp which was OK since internal fuse in bulb, but when the fuse in fuse box was replaced with a MCB the MCB would trip first, so all lights would fail when on bulb failed. And it seems manufacturers stopped fitting internal fuses as the odd lamp I had on a 16 amp MCB welded itself into the holder when it failed, and there is no way to know quality of bulb, so a faulty bulb (i.e. one without built in fuse) can take out an electronic switch, so one has to accept they may need replacing from time to time, and can't really expect the switch to be guaranteed against faulty bulbs. With a ceiling rose rated at 5 or 6 amp, which acts as a junction box, we should have a MCB no larger than 6 amp for lighting, however many homes fitted 10 amp when we started using quartz bulbs, and also seen type C 6 amp MCB which means 60 amp surge to trip it. Any wonder electronic switches fail?