3 Core + bare earth

Farleigh · 19 Aug 2015

Eveving all,

I have a security floodlight that is controlled by a separate PIR. I decided to replace the floodlight but when I disconnect the old one I found a blue, yellow, red and bare copper wire. The new floodlight I have bought only haves three connections for Live, Earth and Netural.

Can someone advise how four cables go into three? I've looked on Google but can't find an answer. Really great for some help.

riveralt · 19 Aug 2015

What terminals (markings) where the blue, yellow, red and earth wire connected to in the old floodlight?
What terminals (markings) are the blue, yellow, red and earth wire connected to in the separate PIR?
Clear photographs of both the incoming and outgoing wires of the PIR would be helpful.

Farleigh · 19 Aug 2015

Sadly this is the problem. I couldn't access the old floodlight wiring as it was rusted solid. As for the wires in the PIR I haven't got a pic of these until I'm back at the property in a few days.

What could my wiring options be?

Iggifer · 19 Aug 2015

Well, red live, bare copper is earth, but then either yellow or blue could be your neutral. The other will be switched live.

If this is controlled by a switch (as it could well be) have a look in the switch, and see where the yellow/blue are terminated

You need to oversleeve the bare copper in Green/Yellow sleeving

riveralt · 19 Aug 2015

It will depend on how the PIR has been wired - normally permanent live/neutral/earth into the PIR and out via the switch live/neutral/earth out to the new lamp.
It is possible that the three core and earth was 'spare' and the person who wired it before used both yellow/red or other combination in the switch live at the PIR and the live at the lamp - with blue (neutral) and earth staying the same.
The key thing is to establish what comes into the PIR and what goes out - then just use the wires you need for the new lamp - say red = live, blue= neutral and earth (copper)(sleeved). The wires themselves do not know what colour they are.

Taylortwocities · 19 Aug 2015

Farleigh said:
Eveving all,

I have a security floodlight that is controlled by a separate PIR.

So, inside the PIR how many cables are there? what wires go to what connections on the PIR?
Is there a switch that controls the operation of the PIR/floodlight combination? How is that wired?

Farleigh · 19 Aug 2015

Thanks all for your help and quick responses. So the floodlight is one of a number of lights controlled by the PIR. Iggifer your right that there is a switch on the wall that can override the PIR and turn all the lights on. When the switch is turned off the lights stay on for a little bit and then go out.

When to say over sleeve the bare copper in green/sleeving what does that mean? Do I cover it and not use it?

Riveralt are you saying the yellow cable could be redundant?

Is it possible to have an educational guess as to what to do with the wires or do I really need to look at the PIR and the light switch to see what the wires are doing?

Thanks everyone again.

Taylortwocities · 19 Aug 2015

If there are a number of lights, my guess is they will all be wired the same.
Surely you can have a look in the back of one of the others and see how it is wired?

riveralt · 19 Aug 2015

Farleigh said:
Riveralt are you saying the yellow cable could be redundant?

As I have said it depends how the PIR has been wired - it could be one of the other colours.

Farleigh said:
Is it possible to have an educational guess as to what to do with the wires

No - when working with electricity - educational guesses are for fools or dead people.

Farleigh said:
do I really need to look at the PIR and the light switch to see what the wires are doing?

Yes you do. With the power off - follow and identify individual wires from the switch supply - to the switch load - from the PIR incoming (supply) to the PIR outgoing (load) and onto the first lamp in the sequence - look inside the lamp to identify how it has be wired and used the same coloured wires throughout.
You need to be able to identify which wire is live/neutral and earth (not understanding what an earth is for is worrying)at each stage.
If you feel this is beyond your capabilities then perhaps you need to get someone in who knows what they are doing.
Here is an example of PIR wiring:
https://www.tlc-direct.co.uk/Technical/DataSheets/Superswitch/6016.pdf

Farleigh · 19 Aug 2015

Brilliant thanks all. I'll look at the wiring see if I can trace each wire and be sure what they are doing. If not then I think I might need to get our electrian over for some £. Will give you an update over the weekend when I'm back at the house.

Have a good evening all.

Farleigh · 22 Aug 2015

So the other lights connected up to the pir have more wires. Will look at the PIR next

Farleigh · 22 Aug 2015

Another light is wired just with 3 core no bare earth.

Farleigh · 22 Aug 2015

The PIR is wired

Farleigh · 22 Aug 2015

The light switch is wires

JohnW2 · 22 Aug 2015

Farleigh said:
Another light is wired just with 3 core no bare earth.

That is "two core with a bare earth" (the 'bare earth" having a bit of green/yellow sleeving over it).

Kind Regards, John

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3 Core + bare earth

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