Messed Up Wiring :(

Talk Electrician Forum

Help Support Talk Electrician Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Jul 17, 2015
Messages
15
Reaction score
0
Location
london
hi guys, hope someone can help me out here, just got a new house, with old dangly lighting,have swapped most of them with no problems, 

but got to the last 1, and surprise surprise, didn't take a picture of the wires, nothing is marked, and in a right state now,

ok it has 4  twin and earth cables coming into it , red . black , and earth, 1 of the reds is live, so i have done what i have done to the others, and connected them all together, , so far so good, so that leaves 4 black cables, 2 lives, 1 switch live, and 1 dead cable, i have put the switch live into the new light, and the other 3 into the other side of the new light, , however, downstairs, there are 2 switches that control 2 lights, and can also be controlled from upstairs, so 3 switches controlling 2 lights, now the problem starts, i cant turn the damn lights off, nothing happens at the switch, so yes yes yes, i have clearly made an error somewhere, can someone point me in the right direction, as to what wire i have put in the wrong place, and to make matters worse, the smoke detectors, are spurred off the lighting, so when i pulled the old rose off, all the wires moved, so i have no clue as to where they go anymore :(

regards

 
hmmm, didnt think of that, got 3 switches to go and check, :)

ok, just removed the 3 sockets, they have light blue and yellow wires, and the live red wire is looped together in a chock block

 
As said , I think you need a meter  or a bell set  to find where they go .  

As Andy says , if you caused a short circuit , a switch could be welded closed.  

If the light won't go out  you probably have a permanent live  in the Switched side .

Can only help with a couple of pointers ,    the red.yellow blue cables are probably for the 2 way switching .

When you say there were 4 cables at your light , chances are they are  L+N  loop in .... L+N loop out .....  L+S/wire down to the switch ...the last one could be  (a)  The feed to your smoke detectors       (b)    A loop feed to somewhere else   ©  if there is a second light  that works with that one then its the loop s/wire + N .   

You need to check it out with the power OFF  and using a meter ,as said ,  you can buy a cheapo test meter for  £8- 9  ...it must have a continuity range powered by it's battery  or may even have a simple buzzer in it .   

 
Last edited by a moderator:
the smoke detectors are trunked and easy to see. still have 4 twin n earth cables coming in, 

so how would you wire this ?

all 4 reds together ? like all the other ceiling roses,

 and how to split the 4 blacks ? ,

in the dark at the moment, lol

ok with all the reds together, and the blacks all separated, we have downstairs lights in 2 bedrooms,

but not in the hallway, bathroom, or 1 of the bedrooms, 

why didnt they mark em up 

 
It seems like...

all your reds will be permanent live (all together)

one of the blacks will be a switched live - usually sleeved red (to the live of the light fitting)

the rest of the blacks will be neutrals (to the neutral of the light fitting)

however if you have 2 x lights working off the same switch then one of the red/blacks will possibly supply that

The best & safest way to figure this out is with a test meter with the power off

 
yes will have to get 1 tomorrow, but as i test them with my trusty light up screwdriver, i have located the switch live, which leaves 3 blacks, 2 are live and 1 is dead

 
Yes  as Noz says  ,  one of your blacks is the switched wire coming up from the switch .  Thats the one that works your light & needs to be marked so you don't mix it with the other blacks which are neutrals .

To answer your question , very few older installations have the cables marked.    Often too, the fuseboards were never labled up either.

Sorry you're in the dark but its difficult for us without being there .

There are things you could try but we can't recommend working live .        You could rig up a simple tester with a battery and a torch bulb ,say, to find the cable to the switch ,  but you MUST SWITCH OFF the power first . 

 
yes will have to get 1 tomorrow, but as i test them with my trusty light up screwdriver, i have located the switch live, which leaves 3 blacks, 2 are live and 1 is dead
If you've done that ...mark the black with tape and connect it to the S/W  in the light  .

Its now likely that  the remaining blacks are all neutrals and would go in the other side of the light  ...but thats a guess .

why are 2 blacks showing as live ?

thats whats baffling me
Try switching OFF all the other lights  ,  it may be back feeds . 

 
ok, have turned off all lights at switches, and still showing 2 blacks as live, 

and if i seperate the reds, then only 1 of the 4 is live, which i guess is the loop in, dont know if this makes any difference, but the light that wont switch off is at the end of the loop i guess, as it only has 3 cables live neutral and earth

 
If theres another light ...( the one that won't go off)    thats what I meant by saying are there two lights that work together ?    If so then you have simply put a permanent  L & N  to it .    The red that goes to that light needs to be with the Switched wire in the first light  ( So  two reds in the light  & three blacks ) 

Sorry but have to leave you in the dark ,  can someone pick this up ?    Good luck . 

 
ok so separate all the reds, and try to figure which one goes to that light, then put that with the switch,

put the other 3 reds together to make permanent live circuit

and then put the remaining 3 blacks together, in the other side, and hopefully away we go. :)

could this be whats live ing up 2 of the neutrals ?

 
grr cant post links :(

DESCRIPTION[SIZE=.9em]Pocket sized. Measures DC & AC voltage, DC current, resistance, diodes & transistor life.[/SIZE]

will this do the job ?

 
or can someone post a link to a cheapy that i can buy from toolstation, maplins or screwfix that will do the job

many thanks

 
Welcome to the forum Anthony,

You could really do with an insulation resistance tester as well as a voltage/low resistance ohm meter, the cheaper units don't offer this, and they are often not really suitable for safe use on mains voltages.

They don't offer the in-built protection, some if applied to a mains voltage on the low resistance range have been found in independent tests to explode.

They are legal for sale, but not in most of our opinions safe for use.

Whilst you may be able to identify the wiring function with a cheap low resistance ohm meter in the way of a multimeter, there is always the possibility that whilst being disturbed to change the light that the wiring may, have become damaged, it does happen.

This would only be found by a bit more in depth testing such as with an insulation resistance test.

Plus you would then also be able to verify the earth fault loop impedance at the light fitting, ensuring that the wiring is safely earthed so that in the event of a fault, it would disconnect rather than electrocute someone, or catch fire.

So realistically you should be looking at something like this:

http://isswww.co.uk/17th-edition-and-part-p/kewtech-single-function-testers/kewtech-kt31-digital-2505001000v-insulationcontinuity-tester-wlo

& this:

http://isswww.co.uk/17th-edition-and-part-p/kewtech-single-function-testers/kewtech-kt41-digital-loop-tester-with-psc-with-hold-down-test-bu

Or, alternatively an all in one tester like this:

http://isswww.co.uk/17th-edition-and-part-p/17th-edition-testers/fluke-1651b-17th-edition-tester

From our forum sponsor Megger Mark on his site isswww.co.uk

The last tester would also allow you to test the function of any RCD's that you have fitted, and is a very well built and reliable device.

The cheapest suitable meter on the Screwfix site, is actually more expensive than what is IMHO a superior product from isswww.co.uk and also as a forum member you would benefit from a discount from isswww.co.uk

 
Top