Question for Electricians - Ceilng Light Switched Live

[Matt H]

A question for the electricians or knowledgable D.I.Y'ers.

 

I'm removing the ceiling rose in the main bedroom to replace the fitting with something more modern. The wiring is a basic loop in ceiling rose arrangement.

 

I was running late and in my haste to get my jobs done and out of the house, I didn't make a note of which of the wires was the switched live.

 

I have three blue wires and one of them is the switched live. I'm wondering if there's an easy way of testing which it is without going through the trial and error rigmarole?

 

Thanks,

 

Matt

[Geo]

just meter it dude, the live one will read 240v or there abouts

[Matt H]

just meter it dude, the live one will read 240v or there abouts

 

Would that work on an incomplete curcuit?

[comorin219]

if your ceiling rose from memory has 3-3-2 connections wire neutral from lamp into the one that takes 3neu, should be 3 live in centre, then in the last 2 connection should be red from lamp & switch live blue if red tape is missing from switch live test with meter & mark with red tape

[Matt H]

if your ceiling rose from memory has 3-3-2 connections wire neutral from lamp into the one that takes 3neu, should be 3 live in centre, then in the last 2 connection should be red from lamp & switch live blue if red tape is missing from switch live test with meter & mark with red tape

 

the wires are now not connected and the red tape is missing on one of the blue wires. How do you test if using the multimeter? - it could be any of the three?

[Geo]

set the multi meter to read over 240v, i set mine at 600v. then put the black probe onto a good ground point.

 

Then use the Red probe to touch the end of the wire, and see what it reads?

[comorin219]

wire the reds in,make sure no blues are touching each other, switch the switch on, test the blues only the switch live will give you 240v 0r if your test leads are long enough disconnect from switch test for continuety

[Matt H]

wire the reds in,make sure no blues are touching each other, switch the switch on, test the blues only the switch live will give you 240v 0r if your test leads are long enough disconnect from switch test for continuety

 

Thanks Comorin, that's brilliant. I've dust off the old multimeter tonight

[Matt H]

set the multi meter to read over 240v, i set mine at 600v. then put the black probe onto a good ground point.

 

Then use the Red probe to touch the end of the wire, and see what it reads?

 

Thanks for the input Geo

[Digsy]

I have a 240V bulb holder on about a foot of flex with probe ends for testing household circuits. Much simpler than using a multimeter (and risking blowing it up if I forget to select the correct input!)

[danny1987]

just one other thing, make sure the switch is turned on when you test at the light.

[danny1987]

i know the above post may seem silly, but when your trying to figure out whats wrong you can easly over look the simple things

[Ricky49]

At the switch connect the red and blue together (with no power on) the with a multi meter set it to audioble or ohms setting and test between the reds and blues until the multimeter beats the blue that it beeps with is the switch wire.

[merckx]

At the switch connect the red and blue together (with no power on) the with a multi meter set it to audioble or ohms setting and test between the reds and blues until the multimeter beats the blue that it beeps with is the switch wire.

 

Great minds thaink alike.

 

No need to test a live circuit when there's a simple alternative.

[Geo]

Well did you figure it out, or did you end up in A & E with 3rd degree burns??

[edge]

Do it safely and turn off the lighting circuit and have a plug in socket lamp to help you see.

Undo the switch on the wall and join the 2 wires together (assuming it's not 2 way wired switch).

Then test for continuity/dead short/lowest ohm reading or buzz test at the rose between a blue and brown wire and this will be your switch line.

[formatzero]

Well did you figure it out, or did you end up in A & E with 3rd degree burns??

 

No need to connect the wires at the switch just switch the switch on and test the pairs at the pendant you will have the circuit made on the pair going to the switch and can test this by switching switch off to break circuit,power OFF

[Matt H]

Well did you figure it out, or did you end up in A & E with 3rd degree burns??

 

Sorted son! Worked it out in the end using the multi, but I can't help thinking that there was an element of luck in my success!

 

Thanks to all that gave input.

[Geo]

Sorted son! Worked it out in the end using the multi, but I can't help thinking that there was an element of luck in my success!

 

Thanks to all that gave input.

 

Nice one bud, least you aint crispy brown,

[Matt H]

Nice one bud, least you aint crispy brown,

 

Well I did do 9 mins on the beds last night so technically I am!

[Matt H]

This site proved useful btw way:

 

Really good 'how too's'

 

http://www.ultimatehandyman.co.uk/diy/electrics/light_fitting/ceiling_rose_wiring.htm