Electrical Interfence When Dimmer Switched On

[BF]

I have a double gang dimmer in my kitchen. One of the switches controls the ceiling spotlights and the other controls the under cabinet lighting.

Recently, when switching on the dimmer for the cabinet lighting, I noticed an electrical interference type noise coming from the ceiling rose of a separate light in my dining room which adjoins the kitchen and is on the same circuit. In addition to that a side lamp on a separate circuit would start flashing as would the cabinet lighting.

This only happened when I put on the dimmer switch for the cabinet lighting so I assumed the switch was faulty. I checked the connections in the kitchen dimmer switch and that within the dining room ceiling rose and all was sound.

I bought a replacement dimmer switch for the kitchen and wired exactly as per the original but it doesn't work. There is power going to the switch. It is possible that it is faulty but I wondered if there might be any other reason?

Appreciate any help / suggestions.

 

[flameport]

Loose connection at the light in the dining room.

 

[securespark]

Concur.

It's not interference, but arcing you are hearing. Please recheck all connections.

If you replace the dimmer with a normal plateswitch, do you still get these issues?

If the switch has failed, could it be the switch and load are incompatible with each other?

 

[BF]

Thanks for the replies / suggestions.

I'll recheck the connections but the noise (arcing) doesn't happen when I put the dining room light on. It only occurs when I put the kitchen dimmer switch on for the cabinet lighting and the noise occurs when the dining room light is off.

The new dimmer switch that I bought, and doesn't work, is the same spec as the one it's replacing. I haven't tried it with another switch yet as I don't have one.

 

[JohnW2]

I'll recheck the connections but the noise (arcing) doesn't happen when I put the dining room light on. It only occurs when I put the kitchen dimmer switch on for the cabinet lighting and the noise occurs when the dining room light is off.

If you are getting noises from the dining room light when it is switched off (but kitchen cabinet lights are on), then it's quite probably rather more complicated than we thought, and it could well be that you will need an electrician to investigate.

Do I take it that the same does not happen when you switch on the kitchen spotlights (which I imagine are probably on teh same circuit as the cabinet lights?)?

Kind Regards, John

 

[davelx]

If you are getting noises from the dining room light when it is switched off (but kitchen cabinet lights are on), then it's quite probably rather more complicated than we thought, and it could well be that you will need an electrician to investigate.

Do I take it that the same does not happen when you switch on the kitchen spotlights (which I imagine are probably on teh same circuit as the cabinet lights?)?

Kind Regards, John

Wiring looped at the rose, dining room is before the kitchen, outgoing loop terminals in the dining room rose loose? Worth checking, turn off power at the consumer unit first!

Yes, I realise that the fact that only one set of kitchen light does this is strange, but we don't know the loads and it's a simple enough check.

 

[BF]

If you are getting noises from the dining room light when it is switched off (but kitchen cabinet lights are on), then it's quite probably rather more complicated than we thought, and it could well be that you will need an electrician to investigate.

Do I take it that the same does not happen when you switch on the kitchen spotlights (which I imagine are probably on teh same circuit as the cabinet lights?)?

Kind Regards, John

Correct. The noise only occurs when the cabinet lights are on and not the kitchen spots. And the noise occurs / elaborates when I turn the dimmer switch up and down. This also causes the cabinet lights to flicker.

 

[JohnW2]

Wiring looped at the rose, dining room is before the kitchen, outgoing loop terminals in the dining room rose loose?

Indeed - that's presumably what others who have responded have been suspecting.

However, as I just wrote, if that were the mechanism, and IF (as seems likely) the kitchen spotlights were fed from roughly the same point in the circuit as the kitchen cabinet lights, then one would expect the same problem to arise if either of the kitchen lights (cabinet or spotlights) were switched on - but my understanding is that it only happens with the cabinet lights. However, there are some 'ifs' in that!

Kind Regards, John

 

[BF]

Appreciate all your help but I can's answer loop questions as I just don't know. I really only tackle electrical DIY projects such as light fitting and socket changes providing I can do a like for like swap!! And I always turn the power off.

My amatuer analysis of this issue was based on the issue occurring just with one of the dimmers and as the connections were all sound I assumed replacement of the dimmer switch would resolve. It could well be that I've been unlucky and the replacement switch is faulty but thought I'd check here in case there is something else I'm missing.

I will get a replacement dimmer (I've replaced the original for now) and see if that works. Failing that I'll get a sparky in.

One thing - if it's a load issue would this not have been present from the outset? I've had the dimmer / lights for over 10 years.

 

[securespark]

As I said, don't replace dimmer with dimmer. Test by replacing with a plateswitch to see if the noise and flickering disappears.

Have you replaced the lamps in these fittings recently?

 

[JohnW2]

... My amatuer analysis of this issue was based on the issue occurring just with one of the dimmers and as the connections were all sound I assumed replacement of the dimmer switch would resolve.

Logical though that sounds, a problem with the dimmer alone would not result in what you have experienced - as has been said, about the only way that noises could arise in the vicinity of the dining room light (when it was switched off) as a result of something else being switched on would be if their was some sort of 'loose connection' in that vicinity - either in a ceiling rose/whatever or perhaps some nearby junction box. However, the fact that only one of the two kitchen lights makes it happen means that even that would not be straightforward.

I will get a replacement dimmer (I've replaced the original for now) and see if that works. Failing that I'll get a sparky in.

As above, I doubt that changing the dimmer alone will cure the problem. You might also try rechecking (with power turned off at your consumer unit) all the connections in the vicinity of the dining room light - boith for 'tightness' and to make sure that none of the screws are partially gripping insulation rather than the wire itself.

One thing - if it's a load issue would this not have been present from the outset? I've had the dimmer / lights for over 10 years.

Indeed, IF absolutely nothing (that you are aware of) has changed, it can't really be be a 'load issue'.

Could you perhaps provide us with a photo of the connections to the dimmer in question and also of connections at the dining room light (power off, again!)?

Kind Regards, John

 

[BF]

Logical though that sounds, a problem with the dimmer alone would not result in what you have experienced - as has been said, about the only way that noises could arise in the vicinity of the dining room light (when it was switched off) as a result of something else being switched on would be if their was some sort of 'loose connection' in that vicinity - either in a ceiling rose/whatever or perhaps some nearby junction box. However, the fact that only one of the two kitchen lights makes it happen means that even that would not be straightforward.
As above, I doubt that changing the dimmer alone will cure the problem. You might also try rechecking (with power turned off at your consumer unit) all the connections in the vicinity of the dining room light - boith for 'tightness' and to make sure that none of the screws are partially gripping insulation rather than the wire itself.
Indeed, IF absolutely nothing (that you are aware of) has changed, it can't really be be a 'load issue'.

Could you perhaps provide us with a photo of the connections to the dimmer in question and also of connections at the dining room light (power off, again!)?

Kind Regards, John

Many thanks JohnW2.

I did take a picture of the dimmer wiring prior to replacing with the new one to ensure that I fitted the wires correctly. See attached.

I have not got a picture of the ceiling rose wiring at present as I satisfied myself that the connections were ok. It's too dark to take one now.

 

[BF]

Here's the replacement and only just realised that my new dimmer is from the same manufacturer.

 

[JohnW2]

Many thanks JohnW2. .... I did take a picture of the dimmer wiring prior to replacing with the new one to ensure that I fitted the wires correctly. See attached.

Thanks.

If (with power off) you temporarily put both wires from the dimmer in question into one of its terminals (doesn't matter which), when you turn the power back on the cabinet lights should be 'on' permanently (as if you had substituted an ordinary {non-dimmer} switch and switched it on) - so you could ascertain whether the noise in the dining room lights then occurs.

Kind Regards, John

 

[BF]

Thanks.

If (with power off) you temporarily put both wires from the dimmer in question into one of its terminals (doesn't matter which), when you turn the power back on the cabinet lights should be 'on' permanently (as if you had substituted an ordinary {non-dimmer} switch and switched it on) - so you could ascertain whether the noise in the dining room lights then occurs.

Kind Regards, John

Do you mean put the live and neutral wires for the cabinet dimmer into the same terminal such as L1?