Lighting circuit error

[Mattbaigent]

Right, I have done a search in the site and found some bits regarding my issue but nothing really answered my issue! I have recently purchased a new ceiling light and in the process of fitting it! I am re positioning the light by about 4 foot. When removing the wires from old ceiling rose I removed the 3 red wires and twisted them to know what groups to put them in, same again for the 2 blacks and then the single black! I connected them all together again into a chocbox with the earth connected to the earth from the light fitting! Turned power back on and bam, fuse went! Went back up to check I had it all correct so I turned the light switch on and connected my multimeter and it said I have a circuit, so I know the wires are in the correct position. I then extended each wire using some more chocboxes and connected it as before but it has blown again! I then put the wires back into old ceiling rose to see if it was the chocbox that was playing up but it blew again. I am lost and have no idea where to look next!!

Thank you for reading this, hope it made sense!

 

[riveralt]

If the lights worked before and they don't now and assuming you haven't messed with the switch, then you have changed something at the ceiling rose end.
You have probably mixed the switch live with the neutral.

Turn the power off and check it is off. Open the switch and check that you have a red in Com and black in L1 or vice versa.
Connect the switch red and earth wire together in a terminal block.

Using another terminal strip connect each of the red and earth wires at the ceiling rose to a separate terminal.
Then using your multimeter on the low Ohm setting test between each of the red wires and each of the earth wires until you have continuity.
When you get continuity that red wire is you live leading from the ceiling rose to the switch - if you can see the corresponding black wire then that is your switch live.
If you cannot then do the same continuity check with the switch black wire and earth and the ceiling rose black wire and earth.
I would add that if you have extended the previous circuit then you will need to check you haven't nicked a wire or otherwise compromised the extension.

 

[Taylortwocities]

Remove anything that you have added, chock boxes etc and go back to where you started. Then do the testing and checking outlined. Sort out the prolem before you add anything else to it!

PS. I hope that you are going to leave the junction point accessible!

 

[Mattbaigent]

Using a multimeter on 2m ohms setting i was getting a 0 reading when connected to the switch wires live and earth and then the live and neutral. Got a 0 reading on one of the lighting circuit and a 1.400 +/- a few on the other wire!

I assumed the switch wire was the switch wire because when I had the switch off I used the buzzer setting and touched L and N leads, then turned switch on and did the same and it buzzed, so from that I assumed that was the switch wire.

 

[Mattbaigent]

And yes, I will be leaving it all accessible!

 

[riveralt]

Using a multimeter on 2m ohms setting i was getting a 0 reading when connected to the switch wires live and earth and then the live and neutral. Got a 0 reading on one of the lighting circuit and a 1.400 +/- a few on the other wire!

I assumed the switch wire was the switch wire because when I had the switch off I used the buzzer setting and touched L and N leads, then turned switch on and did the same and it buzzed, so from that I assumed that was the switch wire.

You need to forget what you thought or assumed because if the extension cables are not nicked and you have not cross wired somewhere along the extension then you only have the ceiling rose wires to check.
You need to set you meter at the lowest Ohms setting m Ohms is too high- check it is working by holding the probes together.
The tests I outlined MUST be done with the circuit DEAD.
You haven't said what the wiring was like at the switch - is it as predicted? Have to connected the switch earth and red wires together there?
Have you separated out the red wires and earth wires at the ceiling rose into six separate terminals?
Have you systematically tested each red against each of the three earths? At this point there is no need to test the neutrals (black wires).
As I don't know what type of meter you have - you can also use the continuity test itself rather than low ohms if your meter has such a setting.

 

[Mattbaigent]

Switched wires red and earth connected and I get a 0.4 reading when on 200. Get the same reading from another wire but 3rd wire does not change. This wire goes on to the bedroom light which has always been fine and not been touched!

 

[riveralt]

Switched wires red and earth connected and I get a 0.4 reading when on 200. Get the same reading from another wire but 3rd wire does change. This wire goes on to the bedroom light which has always been fine and not been touched!

I'm sorry but your reply doesn't make any sense.
Does this switch turn more than one light on?
If as you say there are three cables at this ceiling rose comprising 9 wires then either your ceiling rose has a loop in and loop out LNE and a SWL, N,E or
if another light is linked to it, then you have a LNE in, a SWL, L, E to that ceiling rose and a linked SWL, N, E linked to the other lamps ceiling rose.
Which is it?

 

[DOTElectrical]

Could you possibly take a photo of the connections in your chocbox, seeing always helps.

 

[Mattbaigent]

In the ceiling rose there are 3 wires going in, SW L,N,E and 2 for the upstairs circuit. Power coming in from the light before and power going out to the next light! The light is controlled via two switches, upstairs and down. They had been in the wrong position so I have re positioned them to the correct places (yellow and black in L1 and blue and red in L2 other red in COM) would this have caused the short? I'm sorry if I don't make sense, I'm not hugely knowledgable when it comes to house electrics!

 

[Mattbaigent]

Yes, I am at work now but I can do that tomorrow!

 

[ban-all-sheds]

They had been in the wrong position

And when they were it all worked OK.

so I have re positioned them to the correct places

And now it doesn't work OK.

They had been in the wrong position

You might like to reconsider that.

 

[Mattbaigent]

Haha, I only moved the wires from old ceiling rose into the new one exactly how it was before!

 

[ban-all-sheds]

Although unless you've put a conductor into a switch terminal which was not in one before, or connected a live to the back box, you can't do anything at a switch to create a fault.

I suspect that when you "removed the wires and twisted them to know what groups to put them in" you didn't pay attention.

Easy enough to sort out with a combination of a multimeter and a knowledge of how lights are wired.

 

[Mattbaigent]

I thought I'd wire it up missing out the light. So I have the power coming from previous light and power going to next light connected into a chocbox without the switch wire to bypass the light and it blew again. Would that indicate that it's a problem elsewhere either with the wire or one of the other roses?