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appletree

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Hi,

I recently did a complete house refub, including entirely new electrical wiring and fuse box. Unfortunately the builders (who supplied their own electrician) turned out to be a bunch of cowboys.

They left about a month ago, and today I noticed something very strange in the first floor lighting. There are four bedrooms in the first floor, and every room has a bunch of LED down lights that are controlled by a dimmer. I noticed that when I turn the lights on in two rooms, and turn the dimmer in one room, the LED lights in another room flicker.

Any idea what might be causing this? I an reluctant to call the cowboys back. I am thinking of getting another independent electrician to check the wiring, but I thought I'd ask here first.

Thanks in advance.
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Here is the video of what is happening.

 
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The fact that the flickering happens when you alter the dimmer setting, rather than at random all the time, suggests it's interference between one dimmer and another. That could be due to a high resistance connection at a point feeding all the affected rooms, but then you would typically get some flickering of each or all rooms at random. Obviously if there is any of that, and a loose connection is suspected, it should be investigated as it can arc and overheat.

More likely is that the combination of dimmers and lamps in each room is only marginally stable. Unlike tungsten, where all dimmers worked with all lamps, in this brave new world of LEDs, some brands of lamp don't like some brands of dimmer and vice versa. You can have a situation where a combination just about works but any variation in supply voltage, frequency or waveform disrupts it and varies the brightness drastically. Here, I would think the variations in waveform distortion caused by one room's load on the circuit is disturbing the dimmers in the others.

You could try substituting a switch or a different type of dimmer, or different lamps in one room (even attaching a tungsten lamp for test purposes) and test whether the interference in one or both directions is cured. There might be a significant amount of trial and error although someone on here might recommend a trusted combination of lamp and dimmer that always works.
 
What happens if you try the dimmer in the room where they flicker by way of the other dimmer. The lights seem to dim okay on your video in the room you are turning the dimmer?
 
check that all led lamps are the dimmable type first
They are all dimmable. When the lights in the flickering room are dimmed using the dimmer in their own room, they dim fine.
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What happens if you try the dimmer in the room where they flicker by way of the other dimmer. The lights seem to dim okay on your video in the room you are turning the dimmer?
When using the dimmer in the flickering room, the lights in that room dim fine.

Interestingly the flickering is only affected one way, in that if I turn the dimmer in the room where the lights flicker, the lights in the other room is fine.
 
If you turn the dimmer in the right side room completely off does the dimmer in the affected room still function.
 
Had similar things happen a couple of times, in both cases there was a compatibilty issue with the dimmer and the LED lamps. Why it affected neighbouring lights I cannot say, but it did.

1. Changed a regular switch to a LAP LED compatible dimmer switch. Forgot to change the CFL in the lampholder to dimmable LED before switch on, the CFL flickered as you'd expect, but so did the LED in the adjacent bedroom (on regular switch). Changed the CFL to dimmable LED and all was well.

2. Changed 1 end of a 2 way switching arrangement to a Varilight V-pro dimmer. Also changed the ceiling lights, and their lamps to fancy large dimmable LED filament lamps. Switched on and both lamps flickering, 1 worse than the other, but also the light in the nearby understairs cupboard was flickering too (again on regular switch). The problem was solved by changing the dimming mode of the V-pro from mode 1 to mode 3 (alternative trailing edge). Took me a while to figure that one out, I wrongly assumed I'd cocked up the wiring somehow.
 
Appletree: After checking the compatibility of your LED lamps with dimmer brand/type I would ask myself whether you actually need a dimmer - personally I loathe them and their lighting effect. Also check the dimmers are in the correct mode.

If you call in an electrician - which I think you should - don't just ask him/her to 'check' the circuit. Ask him to completely remake all the connections in at least the part of the lighting circuit in the two bedrooms. If that that makes no difference then remake all the connections for the lighting on the same circuit as the bed room including at the mcb in the CU and its tightness onto the busbar. As a rewire there ought to be no junction boxes tucked away so all connections are at switches and ceiling roses.
 
Hi,

I called an electrician (different one to the one who installed the lights). He looked at the back of the switches and said that the wiring is done in an unusual manner in that rather than the lighting circuit branching off in the ceiling, the live wires for a few rooms come to one of the rooms and then they branch off from there. (see the attached photo) So you actually see the live and neutral wires behind the dimmers, rather than the live and the switched live coming from the lights. He said the cause is that as I turn the dimmer in one room, it is creating some sort of "power pull" and is causing lights in other rooms to flicker.

He said that not only is it unusual to wire this way but there is so many wires in the metal box that wires are getting a bit cramped in there.

To be honest I am not sure what difference it makes whether the live wires branch off in the ceiling or in the box. Not sure whether he meant the cause is the dimmer is between live and the light rather than being between the light and the neutral.

Anyway he said if I change to a on/off toggle switch (rather than a dimmer) the problem should go away.

I also noticed that in some rooms with dimmers, without anything else being touched in the house, the lights sometimes momentarily flicker for about 3-4 seconds and then stop and then flicker again.. and this goes on for about 5 mins and then stops. The electrician said it's probably incompatibility between the LED lights and the dimmer and again changing to on/off toggle switch should fix this.

My question is.. it is true that having live wires branching off in the metal box is unusual way of wiring? When I do the next round of house refurb (maybe in 2021), should I chase the live wire up the wall into the ceiling and re-wire the lights?

Thanks.
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Appletree: After checking the compatibility of your LED lamps with dimmer brand/type I would ask myself whether you actually need a dimmer - personally I loathe them and their lighting effect. Also check the dimmers are in the correct mode.

If you call in an electrician - which I think you should - don't just ask him/her to 'check' the circuit. Ask him to completely remake all the connections in at least the part of the lighting circuit in the two bedrooms. If that that makes no difference then remake all the connections for the lighting on the same circuit as the bed room including at the mcb in the CU and its tightness onto the busbar. As a rewire there ought to be no junction boxes tucked away so all connections are at switches and ceiling roses.
Hi thanks for your reply. I called an electrician and he gave me his assessment (see my new reply below for what he said. I agree, I think I will change all dimmers into an ordinary on/off switch.
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If you turn the dimmer in the right side room completely off does the dimmer in the affected room still function.
Yes it does. I had an electrician come over and check the situation out. Please see my new reply (with a photo) for what he said. Thanks.
 

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My question is.. it is true that having live wires branching off in the metal box is unusual way of wiring? When I do the next round of house refurb (maybe in 2021), should I chase the live wire up the wall into the ceiling and re-wire the lights?
There's nothing obviously wrong with the style of wiring, it's quite normal these days to bring the neutral to the switch, but didn't used to be the case some years ago. Perhaps your electrician is old school. I doubt that is the reason for lights in neighbouring rooms flickering though.

I believe he is correct that there is compatibility problem with the dimmer and lamps, those BG dimmers are leading edge dimmers and so not compatible with all LEDs. I expect changing them to an on/off switch, or compatible dimmer modules will sort the problem.

Please do update us when you get it resolved, it's always interesting to know what the fix was.
 
Appletree - did the electrician actually use his eyes to study the wiring in the image? I suspect not. If one looks carefully at the two brown wires which are middle top and pass downwards once can see that the insulation on the left of the two has been scraped away revealing a small area of the copper conductor. I think there is similar damage to the right hand brown conductor - and I looks to me as if they may have been touching at these points before the switch plate was moved forward. Both these brown conductors are switched lives. The right hand one goes to L2 and almost certainly the left hand one goes to L2 on the other dimmer.

So, please take another look and take some photos from a different angle to confirm my observations. You will need some brown sleeving to cover the damaged areas. DON'T GO STICKING YOUR FINGERS IN WITHOUT TURNING OFF THE ELECTRICITY FIRST
 
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changing to a normal on,off wont work. We have the same issue where switching off and on a toggle in one room causes a flicker to present itself as you toggle on. random LED's in the adjacent room flicker. this problem wasnt there when the lights were plain ballast 4 bulb lay in fixtures.

they are direct wire, no ballast, led lights. No dimmers ever involved in this.
 
That's probably on a two way switched circuit?
no, there is only what I just told you. I am an electrician. So I didnt leave out anything obvious.

I have read online some people saying that you cant have two low voltage control units connected within the same junction box, because of induction.

I believe that switches are truthfully still allowing voltage to seep, and while old lights dont see it, an LED can, and this has cause havoc in commercial settings.

one guy said to put a resister wired inline with the switchleg and it will bleed away (peel off, thwart, whatever word you want to use) errand voltage that makes it past the switch.

But thats doing too much as far as I'm concerned, I'd just as soon do away with the stupid controllers all together. They cost too much anyhow.
 
Hmm please yourself, but the resistors I bought from RS components fit inside a Wago box and did the trick.
 
I'm sure it worked.
But its like, when installing them, if people in the field, have to add things onto the product to assure there is no potential for customer call back, then that product needs to be doing that addition from the factory.
Because knowing that the potential for flickering lights exist, and a customer would see that as "the electrician wired up something crazy"
then one has to explain that its the device, thats just doing too much.
 
For those that are interested, I should have said Capacitors not Resistors, can't seem to find them on the RS web site at the moment, but "RIFA PMR209" was their reference and are the same width as the inside of a Wago lighting box makes for a very neat installation.
 

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