Yet another 2W lighting conundrum (and why I don't like domestics again)

[SUNRAY]

Another simple - just change a light switch job.

Customer reports a big flash, tripping and lights not working.

I arrived to find an obvious brand new 2G switch with a big black flash mark and didn't move properly. Customer insists it has not been touched despite some debris below on the otherwise clean carpet.

I found 5 cables, only No5 having an earth wired with cables 4&5 going off to a couple of 1G switches thus:

I noted the connexions and numbered cables as above then removed the faulty 2G switch
Cable 1 = 40Ω r-bk, 2Ω bk-earth, 43Ω r-earth. (Main switch in fuse board removes earth readings)
Cable 2 = 120Ω r-bk
Cable 3 = 41Ω r-bk, 76Ω y-bk, 139Ω r-y
Cable 4 and switch buzzed out perfectly
Cable 5 and switch buzzed out ok except grey was open circuit and switch didn't move properly.

The 2 associated ceiling roses looked like they are from the 60's with untold layers of paint, as is much of the installation.

And to crown it all there was a power cut.

I have fixed this and sent a report to the managing agent pointing out the importance of regular reports and the need for updating what's installed.

Ideas anyone?

 

[securespark]

Perhaps I'm tired, but I don't understand your diagram! Sorry....

 

[AndyPRK]

I think the switch that was messed with goes between 4 and 5


is this the clue then?

"No5 having an earth wired with cables "

The earth was connected to the live connections ?

 

[AndyPRK]

where do you get cable, that has the colours of cable 3 ?

 

[winston1]

where do you get cable, that has the colours of cable 3 ?

You need a Tardis.

 

[EFLImpudence]

I am with Secure.

What are we looking for?
Are the stars connections? If so, why not use the switch terminal on the lower circuit?

Upper looks like a conventional two-way circuit (even though three strappers) with 2 black connected to switched live.
Lower looks like a conversion two-way circuit with 2 red and 3 red connected to the common strapper.

 

[SUNRAY]

You need a Tardis.

Delorean

 

[SUNRAY]

Cable 1 buzzed out as the supply and by going round the house found one light switched on, I took this to be 'loop in'.

checking cable 2 for resistance I found there are 2 additional lights, I took this to be 'loop out'.

After I took the resistance readings on cable 3, by removing the bulbs relevant to the 2G switch and found the yellow is a 60W bulb for the upper switch and the red is a 100W bulb for the lower switch on a common black neutral.

As I renewed the switches I found: Red of cable 4 is too short to reach 'lower com' and black of cable 5 is too short to reach 'upper com' to do the 3 strapper method.

by making it 3 connexions different (and one extra joint) to how I found it, this works:

I had a 300VA interter with me and managed to function test.

 

[JohnD]

where do you get cable, that has the colours of cable 3 ?

I have some.

I am not alone.

 

[securespark]

I had some red white and blue three core but sadly lost it.

 

[SUNRAY]

where do you get cable, that has the colours of cable 3 ?

It used to be one of the regular colour options

I had some red white and blue three core but sadly lost it.

Still got a bit installed in my house

 

[AndyPRK]

Arh yes. We went thru this before.

I recall the pic which had the white in it

 

[securespark]

Say what you like about older wiring, but those dove-tailed ply-backed boxes were very nicely made.

 

[SUNRAY]

Say what you like about older wiring, but those dove-tailed ply-backed boxes were very nicely made.

And very nicely staying put until an earth is available

 

[securespark]

Of course!