UK Can someone help me wire a new light fitting into an old house with old wiring systems.

[JayLynch712]

I’m a junior electrician, fresh out of college. I did some minor electrical work for a friend buI tried to put up a new chandelier I came across:

• Two Line wires (RED), going into one connector block
• Two Neutrals (BLACK), separated into different connector blocks

- Two CPC wires, going into one connector block.
The chandelier has one line, one neutral and one earth.

I wired it up putting the neutral in one neutral block. When turned on the bulbs barely lit up.
When i switched the wire to the other neutral block it lit up greatly, however could not be turned off.
When i put both neutrals in one block, the light lit up, but tripped the fuse when I attempted to turn it off.
I know little about old domestic systems. Can someone please advise.

 

[littlespark]

It doesn't fill you with confidence that a trainee couldn't work this out. (no offence, its just how you have been taught)

The OP gives no mention of the fitting being ES, but through dead testing with a simple multimeter you can work out which black is neutral and which is the switched live (and as others have mentioned, should have been identified with tape or sleeving) by taking the switch off.

Ive never known it as a "3 plate" system, just called a "loop in"

 

[davesparks]

Ive never known it as a "3 plate" system, just called a "loop in"

You'll find it described as such in all text books and other reference material.

Loop in could be used to describe any method of wiring lighting, but would originally have been used to describe a method of wiring in steel conduit generally used when the conduit is buried in the concrete slab. The back entry besa boxes used for this method are still know as loop in boxes.

 

[Anthony S]

Ive never known it as a "3 plate" system, just called a "loop in"

3 plate wiring as been a term used in the industry since I can remember going back to the mid 1980's

 

[littlespark]

well, I was taught in late 80's in the Scottish borders... where my college tutor and journeymen were all of the same era... it would be how they were taught and passed onto us.
Seriously never heard "3 plate" until I joined this forum

 

[Anthony S]

well, I was taught in late 80's in the Scottish borders... where my college tutor and journeymen were all of the same era... it would be how they were taught and passed onto us.
Seriously never heard "3 plate" until I joined this forum

You can call it the "loop in method" as well because that's how it's described in one of my training books that the CITB produced for JIB Apprentices back in 1984.

 

[westward10]

Three and two plate refer to the amount of terminals on the rose or batten back plate. Ignoring the cpcs two plate referred to a back plate with two terminals, line and neutral. Three plate came about when the loop in terminal was incorporated, three terminals hence three plate or three terminals on the back plate.

 

[JayLynch712]

Ok fixed the issue. Some people were correct. The power went from CCU to the light then to the switch (hence the two line cables) One neutral was fine The other was actually a line. I went back and put one neutral in a neutral block and a line in the other neutral block. Everything works fine ?.

 

[DPG]

Did you sort the earth?

 

[Moley]

I went back and put one neutral in a neutral block and a line in the other neutral block. Everything works fine ?.

Which is exactly how you said it was in your first post. Never be afraid to take photos or even sketch out how things are wired before you pull things apart. If you had made a little sketch and thought through what each wire is doing it can save a lot of hassle later on. I hope you sleeved the switched live so that the next person doesn't have the same problem?

 

[Dave OCD]

Ok fixed the issue. Some people were correct. The power went from CCU to the light then to the switch (hence the two line cables) One neutral was fine The other was actually a line. I went back and put one neutral in a neutral block and a line in the other neutral block. Everything works fine ?.

Jay, Good to hear that you've got the light working but I don't think you've fully grasped the circuit yet. The part highlighted above should say the neutral connects to the neutral [blue] connection on your light fitting and the switched live or line connects to the live connection [brown] on your fitting. You can't have two neutral blocks. All I'm trying to do is make it a little clearer for you.