Replacing light fitting - I'm an idiot

[4pudding]

So I just came hear and read the Wiki and now I feel like an idiot:

...Especially, do NOT assume black-sheathed conductors are neutrals!

A classic DIY mistake is to take down a correctly connected light fitting with more than one cable connected to it then wire up the new one with all reds to the live terminal and all blacks to the neutral (Not forgetting the earth terminal to the cpc's, where present).

...Also, this sounds a little obvious, but if the wiring is not faulty and the accessory or light fitting is working, please ensure it is reconnected in the same manner as before.

So guess what I've just done

Actually it's even worse, my husband took it down and I convinced him to do the above.

We had an electrician test the electrics in our house a while ago and he recommended we change this ceiling light fitting for a plastic one, and then we went wrong as above.

We've taken the old one off and we have two dual-core cables, each with a red and black. No earths at all. The blacks were attached to the previous fitting but the reds were not at all. Am I right in thinking they stay joining in a choc block to complete the circuit?

I'm a bit confused because all the diagrams I've seen have at least three cores - one supply, one to next light, and one for switch.

Please help me redeem myself!

 

[Iggifer]

it could well be that you have the end of line light - i.e. there is no 'next light'

if the two reds were joined together and your two blacks were acting as your neutral and your switched live....all you need to determine is which is your neutral and which is your switched live.

Do you have a multimeter? This is the safest way to work out which is which

 

[4pudding]

I have an AC voltage detector pen, is that any use or should I get a multimeter? Thanks for your help!

 

[Iggifer]

To be honest, the light will work however you wire it - if it's a bayonet fit lamp you can just go ahead and wire it with either black cable in the live or neutral terminals. Just keep those two reds joined together. If it's a screw in lamp or other type, you may need to ensure the correct polarity - this is how

When you have a multimeter, turn the power to the lighting circuit off

put the two blacks into a separate connector strip
set the multimeter to test for continuity Ω
test between the two reds and the blacks
you will need to operate the switch a couple of times to verify but it should beep when you have found the switch live - pop this in the live terminal and the left over black into the N terminal.

 

[Adam_151]

I'm a bit confused because all the diagrams I've seen have at least three cores - one supply, one to next light, and one for switch.

So if every light has a cable off to the next light, sooner or later you'll get to the last one, and have no next light to wire to, so you connect it exactly the same but with the cable to the next light omitted.

EDIT: too slow! / Skim reading fail

 

[PrenticeBoyofDerry]

I have an AC voltage detector pen, is that any use or should I get a multimeter? Thanks for your help!

It is not the most reliable tool to use, but it should indicate the switch live, when switched live.
The safest method is dead testing using a multi-meter.

 

[4pudding]

Thanks, off to Toolstation for one now.

 

[PrenticeBoyofDerry]

Thanks, off to Toolstation for one now.

Don't forget to read the instructions!

 

[EFLImpudence]

Thanks, off to Toolstation for one now.

Don't forget to read the instructions!

If you can't find them then:

Enter,
Fill out order card,
Join queue if there is one,
Give card to assistant,
Get free cup of tea while assistant gets the order,
Pay,
Leave.

 

[bernardgreen]

[Enter,
Fill out order card,
Join queue if there is one,
Give card to assistant,
Get free cup of tea while assistant gets the order,
Pay,
Leave

Return to pick up the items from counter

 

[PrenticeBoyofDerry]

[Enter,
Fill out order card,
Join queue if there is one,
Give card to assistant,
Get free cup of tea while assistant gets the order,
Pay,
Leave

Return to pick up the items from counter

Then leave again!

 

[Iggifer]

Toolstation picks the orders before you pay so bernards addendum is a moot point

Very frustrating, and verrrrry slow, as they trundle off with their basket and e-reader

 

[PrenticeBoyofDerry]

Not if the item has been picked and paid for, and you leave it on the counter!

 

[bernardgreen]

I only mention it as it was something I did recently.

 

[Iggifer]

Ohhhhh I see. My apologies. I misunderstood.

Yea, I too have done that, not in toolstation though, there's never anyone in there when I have to resort to it.