Light Wiring Question

[Charlie35]

Hi,
I want to replace a circular electric fluorescent light in my kitchen with a basic pendant fitting. On checking the mains cable powering the fitting it has 4 wires – Red; Blue; Yellow & Yellow/Green (although the Yellow is not connected to anything).

On the light fitting itself these wires are configured via a connector (chocolate box type) as follows: Red to a Brown wire; Blue to a White wire; Yellow/Green to Earth with the Yellow Wire not connected to anything.

My questions are:
1. Would I be correct in 'saying' the Red is LIVE and the Blue is NEUTRAL?

2. What is the purpose of the Yellow wire?

Many thanks for any advice/help.

 

[He who knows]

1) You might be right. You probably would be right. But the only way to be 100% sure is to test, using a proper 2-pole device like a multimeter or a dedicated voltage tester, not a neon screwdriver or a "magic wand" non-contact one.

Although to be honest it doesn't matter hugely. The new light will work either way round (however you connect it the voltage between one terminal and the other will vary from +325v to -325v 100 times a second anyway). With ES holders you're supposed to have the centre contact connected to line, not the outer screw thread one, as there is a risk that you could touch the thread of the bulb when changing it with the light switched on, but apart from that you'll be fine. Your house won't burn down. Just don't change the bulb with it switched on.

2) Red/Blue/Yellow were the colours in 3-core and earth cable, and domestically that was commonly used to connect 2-way switches together:

The only reasons to need 3C+E at an actual light fitting are either it's an emergency one which has both permanent and switched line, or it has 2-way switching using the so-called "cable saving" method:

But in your case it sounds as if they just used 3C+E because they'd not got twin&earth to hand and CBA to get any.

Usual rules apply - don't work live, test for dead properly, sleeve the earths, make the end of that unused core safe in a piece of chocblock

 

[Charlie35]

Thanks for the info - the light is now working great