DIY Doctor

Outside light

Postby Suzy » Sun May 04, 2008 3:12 pm


I am trying to put up an outside light but the wiring is not familiar to me (this is a new house). There is a brown wire which I presume is live (??), a black wire which I suppose is neutral (??) and then there are two more wires, one is copper and one is grey - what do I do with these??

Thanks for your help

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Simply Build It

Postby ericmark » Sun May 04, 2008 6:42 pm

The cable you have is colour coded for three phase supply. If it is the standard flat gray cable this is often used to wire up two way switches and central heating where the extra core is required. The Brown will be used as line and sleeving will be put on the other two wires to show what they are used for. Brown sleeving on any line and blue sleeving for any neutrals and green and yellow sleeving for any earths. Because of the inductance and capacitance with any cores running next to each other all cores must be used. Where a core is not required it is often connected to earth. You should not allow any cores to be disconnected. Why you would be using this type of cable for an outside light I am not sure? It is not suitable to be exposed to UV light and would need protecting from sunlight. We would normally use a cable with black outer sheave as this colour is more resistance to UV light. But it is the only cable I can think of with bare copper conductor for earth. Maybe I have it wrong?

Postby Suzy » Mon May 05, 2008 3:52 pm

Hi Ericmark

Thanks for getting back to me. This house is a new house and the builders left a plate on the wall outside with wiring ready to use for an outside light, the cable coming from the house has four wires, brown, black, copper (bare) and a grey wire the same size as the brown and black ones. The light switch for the outside light is on the same panel as a light switch in the kitchen.

I have tried putting the small grey wire with the copper earth wire but this didn't work. I have now taped it up and left it unattached but this hasn't worked either.

I hope I'm explaining this OK! Thanks for your help.

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Postby sparx » Mon May 05, 2008 7:58 pm

Hi Suzi,
the wiring is available so that you can fit different types of light, ie switched manually or using a built in dusk to dawn or PIR movement detector type.
Convention is that brown is Live, black [which should have a piece of brown sleeving on it] is a switched live from indoor wall switch & grey should be sleeved blue as neutral, bare wire should be sleeved with green/yellow as earth.
if fitting a standard light then earth, neutral & switched line are used with permanent live put in a spare term. block not connected to light.
If fitting a light with any sort of sensor/detector then other combinations apply, look at 'clue sheet' supplied with fitting and if still unsure come back here,
take care! switch off at mains when connecting! you'r a long time dead!
regards SPARX
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