How to install external light?

[keith666]

Hi, am looking for info on how to install an external light and wire in. Specifically if it is possible to add a switch for external light from existing switch for internal light?
I am an engineer and competent at most things apart from "sparks" work i'm able to do the work but just need to know what i can and can't do from a standard wall switch.

Any info appreciated and have a good new year.

cheers

Keith

 

[breezer]

look in the for refernce section

 

[Big_Spark]

Keith, what you can and cannot do via a normal switch much depends on how that switch has been wired originally.

Remember that generally switches do not have neutrals wired to them, but you need one for the light to work.

You would be far better off taking a LNE feed from a light position internally to a point where you will control the external light from. How you control the light will depend on it's purpose..ie; security or simle illumination as required.

If Illumination as required, then I would suggest a double pole switch so that when the supply is disconnected, NOTHING goes to the external switch that is connected to the rest of the active circuit..although this is personal choice.

If you want the light as a security light, then it will need a unswitched permanent live to it so that it is triggered in the manner you desire..

A bit more information would be helpful, the type of light to be used, what it is used for, what type of installation do you have..ie: TT, TN-s or PN-C-S (PME)

 

[keith666]

Thanks for replies, the light would ideally be for simple illumination i.e. on/off from switch. Would I be better running a cable from a light to a new switch to control the external one?
As to the type of installation I have i am unsure...will have to do some research on your site and others.

Thanks again

 

[Big_Spark]

Keith, in that case the easiest way to to achieve what you want is to take a supply from an existing light point under the floorboards, take this supply to a Junction box above where you want to switch the light from.

From here you need to take a pair+cpc down to the switch, one core will be connected to the live feed and will feed the common terminal of the switch, the other core will connect to the L1 terminal of the switch and back to the Junction box. This core will then be connected to the LIVE that feeds the light externally.

The neutral from the LNE you brought in will connect to the Neutral feeding the switch, all the cpc's (earth's) will connect together in the junction box.

The JB you need will be a FOUR terminal 20A type..six terminal 20A would obviously do the job as well.

I asked the supply type you had as some types of automatic switches (PIRs) can effect RCD's and if you had a TT system this could be a potential, although rare, issue.

I wouldn't worry about it under the circumstances..

 

[keith666]

Thanks for all the info, have a good new year.

cheers