Switch wire not labelled.

[pete01]

Was thinking about when people ask how to connect a light and they have 3 twins and the switch wire isn’t labelled on the switch cable.

The question is asked if they have a continuity tester, if they do great....but if they dont what do we think of this?

Put the 3 pairs (reds and blacks) into separate connector blocks. (6 connectors)

Remove one wire from the switch and put into a connector block.

Put any 2 sets of red and blacks together red to red black to black.

Turn the power on and check if all the lights work in the house, rotate the sets until they do, (turning the power off each time) when they do the set not being used will be the switch drop cable?

Thoughts?

 

[flameport]

If people don't have any kind of testing equipment then they should go and buy some.
Ridiculous that people should expect to do electrical work with no testing equipment at all.

Even a cheapo £15 multimeter from Screwfix or similar would be plenty good enough for basic dead testing.

 

[pete01]

If people don't have any kind of testing equipment then they should go and buy some.
Ridiculous that people should expect to do electrical work with no testing equipment at all.

Even a cheapo £15 multimeter from Screwfix or similar would be plenty good enough for basic dead testing.

Fair point but hypothetically my non tester way would work? No?

 

[sparkwright]

Fair point but hypothetically my non tester way would work? No?

Sounds like a plan - even electricians get asked to fix things with no notice, and they don't have their own tools and testers with them.

 

[JohnW2]

Fair point but hypothetically my non tester way would work? No?

Yes, as far as I can see, it would work (so long as the cable with the outgoing L&N actually was feeding a 'light in the house' {with a functioning lamp/bulb!}, rather than, say, a feed to alarms!) - but it is very 'contrived'

As has been implied, if someone needed to take such an approach, it's probably questionable as to whether they should be doing the work ... but sparkwright has made a valid point that it can be useful to be able to take such pragmatic approaches if, or whatever reason, one finds oneself without any testing equipment (and with nothing one could use for 'improvised continuity testing)

 

[pete01]

Ive often thought about giving out this advice but it probably isn't wise for a beginner....is it?

 

[JohnW2]

Ive often thought about giving out this advice but it probably isn't wise for a beginner....is it?

That was really my point. Such 'clever' approaches (and there are many others like that one) can sometimes be useful to 'non-beginners', but are probably not too wise for 'beginners' - the important point being that one really should fully understand what one is doing and why it works (whereas the 'beginner' might just follow the instructions blindly, without any 'understanding').

Particularly if one doesn't 'fully understand', it is certainly essential to follow your instructions exactly. When I first read it, I missed the bit about disconnecting one of the switch wires. I was therefore thinking that, when trying the various 'combinations', when one re-energised the circuit one would EITHER see all the other lights working normally OR (if the switch were 'on') 'hear a big bang'

 

[Notch7]

Fair point but hypothetically my non tester way would work? No?

My advise is label everything, take pictures and write it down.

Then you should able to get back to where you were before it all goes wrong.

Lighting circuits are a complete nightmare IMO

 

[JohnW2]

My advise is label everything, take pictures and write it down. ... Then you should able to get back to where you were before it all goes wrong

Very sensible - but, as I need not tell you, in the real world it's only too common for people to come asking for help/advice after they have disconnected all the cables without having first labelled, noted or photographed anything

 

[SUNRAY]

My advise is label everything, take pictures and write it down.

Then you should able to get back to where you were before it all goes wrong.

Many times we see "My decorator/plasterer etc took the light down...", it is very possible he will remember what's what but is then off the job.

Lighting circuits are a complete nightmare IMO

Yes they can be quite complex at times and often twice as many cables in a rose compared to 'standard'.

 

[Harry Bloomfield]

Very sensible - but, as I need not tell you, in the real world it's only too common for people to come asking for help/advice after they have disconnected all the cables without having first labelled, noted or photographed anything

Yep, very true, after all it's only a few wires, how complicated can it be - so they wade in, without a thought....

I prefer the simple, no contact needed, volt stick method, with circuit powered up. First, find the L. With switch open, connect L, in turn to each red, until red at switch shows to be live - the black of that T&E is your switch wire at the ceiling, so mark it. Rest of the reds, must be looped reds, to other lights.

Not being so risk averse, I would do all that, with it live, but using extreme care.

 

[pete01]

My advise is label everything, take pictures and write it down.

Then you should able to get back to where you were before it all goes wrong.

Lighting circuits are a complete nightmare IMO

Thanks but I can usually get a lighting circuit back working, this was aimed more at a beginner who might have forgot how it was connected

 

[ebee]

I must admit my first thought was BANG until John pointed out the bit about disconnection the switch which I too had missed mentally.

I think Flameport`s comment is the best and I reckon he would not be too keen on someone attempting to use a multimeter instead of approved testers in approved ways yet he is mindful of perhaps the "least worst" if not the proper way to do, being pragmatic.

To the OP.
as a thought exercise, its merely a perm any 2 from three connections and seeing which works and which two do not work.
If it was done with a simple battery and bulb (lamp - filament lamp) I would be happier than someone using the mains in this way.
I know that plenty of us could do it but one quick mishap is perhaps a little risky?
Actually a battery and bell/buzzer might be easier as a simple quick cheapo continuity tester.

 

[pete01]

To the OP.
as a thought exercise, its merely a perm any 2 from three connections and seeing which works and which two do not work.
If it was done with a simple battery and bulb (lamp - filament lamp) I would be happier than someone using the mains in this way.
I know that plenty of us could do it but one quick mishap is perhaps a little risky?
Actually a battery and bell/buzzer might be easier as a simple quick cheapo continuity tester.

I agree it was just a thought going through my mind.

I was explaining it to my wife but she said "stop" I have no idea what you are talking about

Fair enough so I shared it with you lot

 

[Harry Bloomfield]

Actually a battery and bell/buzzer might be easier as a simple quick cheapo continuity tester.

Many meters these days, include a buzzer continuity tester, so all that is needed is a bit of wire to extend the leads.