Link between L1 on different one way light switches

[2BobSparky]

Took a 2 gang switch off a wall in a shop to investigate after workers had complained of crackling sounds and more recently tripping of the circuit.

It appeared that there was a loose termination at the L1 terminal on the back of one of the switches.

The unusual thing I discovered though was the wiring, with brown used for the L1 switch lines to the field and blue used into the common terminals on each 1 way switch on the 2 gang plate as well as a link between each L1 terminal!

1 switch controls 1 bank of around half a dozen or so LED down lights while the other switch on the same plate controls a section of LED uplights.

Both common feeds (in blue :-/) to the back of the switch are isolated by the same MCB.

The brown link between each L1 terminal when removed makes the lights not work!

It would seem I've opened up a can of worms here, but the shop has been open for around 3 years and the wiring has been like this the whole time!

I'm concerned that since I've found this and it's not right that I should report it and suggest a course of action for the shop manager.

 

[westward10]

Are the blues identified with brown sleeving. Did you check switching polarity was correct.

 

[Rpa07]

Is it not just two twin and earth switch wires that have not be sleeved for identification - have you discovered a junction box or a 3 plate up in the ceiling somewhere. The link reason i can't think except it may be obvious when you get to that junction. Further investigation!

 

[Des 56]

The unusual thing I discovered though was the wiring, with brown used for the L1 switch lines to the field and blue used into the common terminals on each 1 way switch on the 2 gang plate as well as a link between each L1 terminal!

1 switch controls 1 bank of around half a dozen or so LED down lights while the other switch on the same plate controls a section of LED uplights.

If your feeds were in on the Blues as you state then the lights could not switch independently

 

[streamer]

Were the blue wires linked together? If not it sounds like whoever installed it just used the wrong terminals. Check the polarity.

 

[Richard Burns]

Sounds like someone has wired each set of lights as loop in wiring in twin and earth and when they got to the switch they realised they had two feeds coming in from the same circuit and linked them together, perhaps disconnecting one of the feeds at the loop in point.
Then with the link removed and the terminals re tightened then one set of lights would not work.

 

[The Ghost]

I have seen similar arrangements In diverse places. If it worked before everything is ok with what is there. I have found that such an arrangement is like you link the live to the next switch for the feed to the other bank of lights. Fairly common. The colours and the fact the switch is "upside down" is just bad wiring practice. So now the other wire going from the link at L1, I would guess is a supply to an emergency light. Just a wild guess, as I have seen it quite a few times before it is not impossible. Of course pics always help.

 

[Pat H]

I hate lighting circuits when you have to unpick what's happening.
Had on the other day with an unused live in a ceiling rose. Turns out the live had been linked across in a 2 gang switch so wasn't needed in the feed to the light but the neutral was.

 

[electric al]

I would be inclined to agree with Vortigern , sounds very much like the link at L1 is a supply to an emergency light .