2 way light help

[chris76]

Hi all new to the forum, just after a bit of advice.

I'm a qualified, registered kitchen fitter so don't really work on lighting circuits, however after doing my usual switch change to chrome sockets at the end of the job, customer has pointed out something strange which i cant get my head around.

on the dining room 2 way lighting system you can switch between the light fine, however when you leave one of the on the switches open, and switch off at the other the bulbs are staying on very faintly.

iv attached before photo of the old switch and the new switch after double checking all wires were fitted correctly. you can also see the light in question.

is there anything obvious i'm missing, while replacing the switch i did it one terminal at a time so im 90% certain everything went back correctly.

thanks in advance

 

[freddo]

was the light replaced at the same time?

 

[littlespark]

Put the old one back on and see if it’s the same. (maybe it’s always done that but only just noticed)

There can be an induced current in cables which can be just enough to bring on an LED lamp very faintly,

The metal switch plate should also have an earth from the back of the box.

 

[chris76]

Put the old one back on and see if it’s the same. (maybe it’s always done that but only just noticed)

There can be an induced current in cables which can be just enough to bring on an LED lamp very faintly,

The metal switch plate should also have an earth from the back of the box.

The old switch has gone, I think the customers just worried in case there’s going to be a fire.

I just want to be sure there’s nothing obvious before I polliitely suggest they just have to live with it the two switches are only 10 foot apart

I couldn’t even get it to do happen without them showing me,for whatever reason there’s a certain way round it will only happen, if your walking between the two switches it’s fine
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Also should’ve mentioned they have a second exact same light in the same room, which is controlled via a single way and it leaves no residual light.

Also the two lights were fitted by the customers father after I changed all the switches
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was the light replaced at the same time?

Sorry just seen this, no the light was done after I changed the switches

 

[freddo]

The issue is with the LED bulbs and is quite common now. As the customers father is responsible for the issue it's best to leave him to deal with it!

The lights light dimly from being charged by capacitive coupling on the 2 way switch wires. Changing bulb types can help, some are more affected than others. I assume the bulbs are mains G9?

 

[James]

In simple terms, some "volts" are leaking into the lighting supply cable.

remove cable B from the circuit at both ends

check if light iluminates dim under the following conditions
left sw up-right sw up
left sw up-right sw down
left sw down-right sw up
left sw down-right sw down

only 1 combination will allow the light to come on at full brightness.
note if any combinations make the light come on dim

Reconnect cable B
Disconnect cable C

repeat above combinations of switching.
again, light should only come on at full brightness under one of the switching conditions listed above.

if the light comes on at dim brightness for both sets of tests then the most likely cause is induced voltage from parallel cable runs as mentioned before.

if the light comes on at dim brightness only under 1 set of tests, the likely culprit is a faulty switch.

 

[chris76]

The issue is with the LED bulbs and is quite common now. As the customers father is responsible for the issue it's best to leave him to deal with it!

The lights light dimly from being charged by capacitive coupling on the 2 way switch wires. Changing bulb types can help, some are more affected than others. I assume the bulbs are mains G9?

Yes they are, ok thanks for your help, it’s confirmed what I thought and it’s just one of those things they’ll have to live with

 

[SparkyAndGeorge]

Look into a "snubber" or replace the lamps for halogens.

 

[Strima]

Electroboom explains it quite well in a measured and entertaining way...

View: https://www.youtube.com/watch?v=_bgUy6zA0ts&t=465s

 

[robd]

Electroboom explains it quite well in a measured and entertaining way...

View: https://www.youtube.com/watch?v=_bgUy6zA0ts&t=465s

He's a bit of a lad that one ?

 

[MDJ]

and it’s just one of those things they’ll have to live with

Gasp, please don’t change any of my switches