back to front wiring of ceiling lights

[deltafart]

Hi

I cant believe how much of a muppet I feel but am stuck here with what must be a simple problem so would appreciate any input:

I replaced a couple of pendand lights in one room with fixed bayonet type (like the ones in a bathroom) and 'thought' I'd copied the previous setup correctly but the single switch for both lights now turn off one light when turned on and visa versa! D'oh.....

It's a looped in circuit and where the swtich cable black wire which should be marked (but isn't!) with a brown or red sleeve goes into the first light fitting 'Live' terminal and the other 2 black wires go into the Neutral terminal (the 3 reds go together in a block and the 3 earths together) which means to me that the black wires I've somehow got ar*se about face? I cannot definately say with the cable which is Feed/Switch/to other light (maybe I should be a electric power detector?) I'm struggling to work this out and am completely exasperated (not to mention embaressed!)

Any help would be really appreciated.
Cheers
Rob

 

[holmslaw]

..

 

[1john]

If you get a multimeter your life will be better, only need to spend about £10 on one, it needs to do voltage and continuity tests.

 

[deltafart]

Holmslaw
Definately there's not 2 switchlines... there's 3 cables going into the first ceiling rose which I'm assuming is the feed/switch cable/then the 3rd cable to the end ceiling rose; however I can't determine with certainty which is which so I think the next stage is to buy the multimeter as per 1Johns response. However I still think that this is a silly oversight on my behalf. I've looked and looked at the first ceiling rose and there's only so many configuratiuons it can take! given the reds & earth's are together it must be something I'm doing with the black wires. Without definately knowing the switch black (that should have the red sleeve) is the the one I'm putting into the live terminal I guess I would struggle.... hey ho

 

[1john]

so you have three cables in one ceiling rose and how many in the second? Both lights are switched from a single switch only??

 

[deltafart]

That's right 1John both lights from the single switch. I've got 3 cables into the first rose then a single cable (twin/earth) into the second rose. Like I say there's only so many ways it can go! I know I'm going to kcik myself when it's resolved! lol

 

[1john]

At the first light you have -

1 cable - perm live and neutral
1 cable - switch cable
1 cable - link to second light

The three reds were not together!!!!!

The perm live should be in the loop terminal with the feed to the switch

The switch return should be in the terminal which supplies the live side of the lamp and so should the red wire from the cable that feeds the second light

The neutral feed should be in the terminal that goes to the lamp and so should the black wire from the cable that goes to the second light

All the earths should be in the earth terminal.

These cables will be easy to identify with a multi meter and will not result in you blowing fuses, damaging MCB's or switches either

 

[holmslaw]

..

 

[deltafart]

Gents

I really appreciate your responses, and at the risk of sounding thick! I need to get my head around the guidance tomorrow morning if that's okay? (I've got 3 kids under 6 years running riot now) I will follow the logic with laptop by my side as I go through it physically and let you know how I get on if that's okay?

Your help is really well received

Cheers
Rob

 

[fireman22]

hi delta,
switch off the wall switch and switch off the breaker 1st.
put 3 sets of three connector blocks one on each of the 3 twin cables you have.
put the old pendant drop brown & blue with a known good bulb into one set of blocks, red & black, switch on the breaker repeat this (switching off breaker in between) until the bulb lights, this cable is your mains in, mark it with a perm marker, (if you are lucky it will be the first one you try )

switch off breaker, double up in connector block with one of the other red & black, put known good bulb in your 2nd light fitting, when this lights mark that cable switched live & neutral so you know it goes to your 2nd light

the last cable is your switch wire and you should put some red tape around the black cable so its a twin red.

then put the the red of the mains in, in the centre terminal with the red taped cable.

the other 2 reds go in the live terminal (end terminal with two holes)

the 2 blacks go in the neutral terminal (end terminal with three holes)

just keep switching off breaker in between so you are not working live.

the only thing you may have done is damaged the light switch but let us know how you get on following these steps.

this way you wont need to buy anything

 

[1john]

How many times can an MCB operate and still remain functional and within tolerance?

Is it a bad or dangerous way to identify cables using test equipment or is trial and error safer?

 

[fireman22]

what do you mean by that post John?

 

[1john]

Could you answer those two questions? You are advising someone to energise a dead short arn't you?

 

[fireman22]

err, No. where are you reading i am saying energise a dead short?

i am just saying if he wants to fix it without having to go out and buy anything, he can.

 

[fireman22]

John, i am a fully qualified electrician with my own company 3 vans on the road 6 employed.

if i went round one of my friends house for a drink and when i got there he said "come and have a look at a light i can figure it out whats what"
without any meters, using the instructions i have given, i could get the light working
i know i`m an electrician but anyone following those steps could get it working

the only problem he may have as i said is that he may have already damaged the switch