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I tried changing my Living room ceiling lights. It has one switch that controls 2 lights. Each of the Ceiling light had a Ceiling rose. Being first timer, i removed one of the Ceiling rose, but later i realised i shouldnt have removed it. So i fixed it back. So not sure if i messed up between "Switch wire and loop wire". It was all red so i fixed exactly as it was before. But when i fixed light, that one was always on eventough i switched it off. The other light fitting is working fine.
Couldnt find out what is causing this issue. I tried changing combination of red wires between Loop and Neutral terminals in Ceiling rose, but no luck.
Since this is a old house, there is no indication of Switch wire as everything was red.

Can you please help ?

Suresh wrote:Can you please help ?

Question:
How do you suppose someone on a computer is going to know what error you have made, when as you said (and it's not unusual)

Suresh wrote:as everything was red.

I assume you have no test equipment, if you had you would have tested by now. You are going to have to get someone to look at it for you.

Sorry it is not the answer you wanted to hear.

What test equipment should I have ?

If I were you, I would still go with my first suggestion, get someone in who not only knows what they are doing, but do it safely

In an ideal world you should have a MFT Click here

But for what you need to establish you could use Click me

and one of these Click me to test the above device.

It also depends on how competent you are, the above test equipment does not come with knowledge and or experience and costs more than getting someone in. At the end of the day, it is your choice, but you did ask.

Pictures are always good, but the ceiling rose with normally have 4 connections, a earth clamp, and a row of terminals arranged as 2, 3, 3 which should be switched line, permanent line, and neutral.

Some where you have the permanent line (often called loop) connected to the two terminal part of the block instead of the switch line.

This may not be at the light stuck on, but at the light which is working, I am sure if you tried enough times you could strike lucky, but as @Mr White says the answer is to test.

To test with low risk likely you will need some connector block so wires can be individually terminated and tested with some form of tester, with a low risk of touching a live wire.

Personally I use one of these [attachment=0]Clamp-meter-small.jpg[/attachment] I find when using the leads to test being able to hang them from the clamp helps, even when not using the clamp to test with, in theory we should test for voltage with a meter having no switch or battery so it can't be switched to wrong range or have flat battery, and it should be tested before and after with a proving unit.

In real life only had one job where we used a proving unit, it was instant dismissal if caught without the proving unit, but only had that on one job.

The main danger when testing is ionisation of the atmosphere, this is what happens when the old tungsten bulb failed with a bright flash, and what we want is to avoid any sparks, this can happen if a meter is on current instead of voltage, but since the meters show measure current with non contact, you can't make that error with the meters shown, so safer for the DIY guy.

The yellow meter to left was my first, bought it when working in Hong Kong, they will cost now around £15 for a really cheap one, where with a normal multi meter can pick one up for less than £10, however likely the leads supplied with them are not suitable for mains voltage.

The one on the right cost me around £35 I was lucky, seen same meter for £50, I paid the extra as it will measure down to 0.001 amps which is handy for finding RCD tripping currents, and it also measures DC current, most clamp on meters will not, it also measures non contact voltage. Between that meter and my insulation tester I can find most faults. The insulation tester also cost £35.

However my son has my other meters, which I have to get back if I want to complete the paperwork, and issue a minor works or installation certificate, but rare I need to issue them now I am retired.

However without some test equipment it will be hard to correct the error, and you have to consider if best to spend on the test equipment and learn how to DIY, or pay for an electrician to fix it?

You need to be aware mains bites, even with RCD protection, and although some times one can be lucky and find a fault with a neon screwdriver, in the main they are only any good for protecting against borrowed neutrals, so you will need to pay out for a tester, even if the bulb on two wires used years ago when an AVO Mk8 cost around £150 back in the 80's.

So your looking at some thing like a LAP MS8922B AC/DC 2-Pole Voltage Tester with RCD 400V from screwfix as cheapest easy to locate tester which does not involve waiting for the post to arrive, at £9 approx.

You can try posting pictures, maybe we can advise further, but not seen many ceiling roses with all red wires, I would have expected not including the pendent either 4 red and 2 black when twin red used to switch, or 3 red and 3 black with one black sleeved red, when red/black twin and earth used.