I'm replacing a strip light, but the wiring on the light I'm putting up does not match that of the strip I'm taking out.

Coming out of the ceiling there are two cables. The larger white cable contains a live, a neutral and an earth wire. Alongside it is a white cable containing one live wire.

Here's the wiring of the light that's being removed. It has a row of three screw holes plus an additional point for the earth. The red wire from the single cable is wired to the upper screw. The three screws are labeled P, N and P - (Positive, Neutral, Positive). There are two bulbs on this light.

I'm removing two of these lights, each with two bulbs. There are two dimmer switches on the wall, each dimming one bulb on each of these units.

wiring of the light being removed

Now here's the light that will be going up. There are three screws; a live an earth and a neutral.

layout of the light going up

I don't know how to assign the four wires coming from the ceiling with these three screw holes.

Any help would be much appreciated. I'm in Australia.

  • Putting your location would help here. Many of our posters are from North America and it is clear you are not. I'm sure someone will be along that is familiar with your areas wiring. Jun 6, 2015 at 12:06
  • The "positive/neutral/positive" part makes me wonder if the dimmers are changing AC to DC for the old lamps...
    – Ecnerwal
    Jun 6, 2015 at 14:52

1 Answer 1


If I understand this situation correctly, both red cables are Positive and carry the current from switches. You may want to check both red cables if they really correspond to these 2 switches. If so, I guess You need to choose which circuit (1st red + N + E or 2nd red + N + E) You want to use, cuz I guess You will be using just 1 switch/dimmer (as Your 'new' light needs only 1 Positive cable).
I would check (for safety meanings) red cables (if both run current while switch/dimmer is on), put 1 red to 'A', 1 negative to 'N', 1 earth to 'E' and ISOLATE remaining red cable (using some isolation tape or else). If everything goes well, 1 switch will turn Your 'new' light up and remaining switch would be obsolete.
I'm not sure about all the fixing (if it needs to be done by qualified worker), but I did something like that several times myself.

  • I'll second the comment about 'fixing'. When in doubt, hire a pro. Safety is paramount. Jun 9, 2015 at 14:19

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