Odd wiring in ceiling rose...

[Ballboy]

I've changed out a few ceiling lights in houses I've owned, usually just a quick swap but on going to change one out today in my new flat I found a blue wire to live and a blue/brown wire with a red bit of rubber or tape on it to neutral and no earth. I checked one of the other lights and it was all as I would expect so I rooted around in the hole and pulled out 4 connector blocks from the ceiling running out of 3 mains wires, the initial blue and blue/brown wires are attached to two black wires by connector blocks, these two extension wires also seem thinner than the ones they connect into. The red wires from all three connect to each other in a connector block and don't come into the light rose at all, I also found all three earths similarly connected to each other in another connector block. Please see image below.

ceiling rose

• Ballboy
• 3 Jan 2014
• 1

odd wiring in ceiling rose

Now, should I remove the two extention wires and just wire it in the usual manner (eg 3 reds to brown in the light, the 3 blacks to blue in the light and the three earths to the earth in the light or should I just wire the blue to live and blue/brown to neutral (as it was in the old light) and connect the three earths to the earth in the light?
Thanks in advance for any tips.

 

[EFLImpudence]

What is odd is that you have never seen this before.
It is the usual way it is done.

As it works why would you want to alter it?

Just connect your new light to the same wires as the old -
plus connect the CPCs(earths) to the new if it is required.

 

[rjm2k]

It will partly depend on the new light fitting, it's supplied terminal block and the amount of space available in the rose. I think it's a bit naughty to have shoved the blocks into the void like that but probably not uncommon.

You have a loop in and out plus a switch cable.

The black with red tape is the switched live.

 

[EFLImpudence]

Study -

 

[bernardgreen]

Now, should I remove the two extention wires and just wire it in the usual manner (eg 3 reds to brown in the light, the 3 blacks to blue in the light.

NO if you join the three blacks together then the switch ( at the end of the cable with the tape on the black ) will be across the live and neutral. When you switch it on you will be shorting live and neutral together in the switch. Could ba big bang, the fuse should blow and the switch contacts will be damaged.

 

[PrenticeBoyofDerry]

today in my new flat I found a blue wire to live and a blue/brown wire with a red bit of rubber or tape on it to neutral and no earth. I checked one of the other lights and it was all as I would expect so I rooted around in the hole and pulled out 4 connector blocks from the ceiling running out of 3 mains wires, the initial blue and blue/brown wires are attached to two black wires by connector blocks, these two extension wires also seem thinner than the ones they connect into.

Not unusual to come across this, the block shouldn't really be popped up in the void unless enclosed in something like a choc box. the thin wires would have been a short length of two core flex, and earth should always be connected to an earth terminal on the fitting if one is present. It does sound like the flex has be installed in reverse polarity though, but your image does not show that!

The red wires from all three connect to each other in a connector block and don't come into the light rose at all, I also found all three earths similarly connected to each other in another connector block.

That is normal

Now, should I remove the two extention wires and just wire it in the usual manner (eg 3 reds to brown in the light, the 3 blacks to blue in the light and the three earths to the earth in the light

That would not be the usual manner

or should I just wire the blue to live and blue/brown to neutral (as it was in the old light) and connect the three earths to the earth in the light?

Depending on your fitting type, you could make the flex redundant and terminate the red sleeved black at the live side of lamp, the blacks to the neutral side, the earths to an earth terminal if present or left in the connecter if a class II/double insulated light.
The reds can be left connected together or if there is a spare on the fitting for the live loop, they can go into that.

If your light fitting is metallic it is very likely to require the earth to be connected to it.

 

[ban-all-sheds]

That would not be the usual manner.

Sadly it is all too usual for people who think they can work on lighting circuits even though they do not understand how they are wired.

 

[Ballboy]

Thanks all!
I'm only a DIY'er and recall in the past only three wires that I simply replaced like-for-like from old light to new and not as I found today so thanks for your help in clearing this up.

 

[ban-all-sheds]

I'm only a DIY'er

But as you can see, you do actually need to know as much as anyone else about how lighting circuits are wired if you want to fiddle with them.

Fortunately you asked, rather than just assumed you could match all the colours up.

• http://www.google.co.uk/search?q=electrical+circuits+101
  
  
• http://kevinboone.net/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• //www.diynot.com/wiki/electrics
  
  

 

[securespark]

As per EFLI's diagram, if you are familiar with ceiling roses, then the arrangement you have photographed is identical, save for using blocks instead of a rose.

The reds on their own would have gone to the loop terminal. The earths would have gone to the earth terminal and will connect to the fitting if it requires one.

The single black conductor with the red marker is the switched live that goes to the fitting.

The two blacks are the neutral to the fitting.