Adding outside light to existing outside light.

Discussion in 'Electricians' Talk' started by Jeffro86uk, Feb 12, 2024.

  1. Jeffro86uk

    Jeffro86uk New Member

    Hi.

    I’ve currently got an outside light (pictures attached). It’s a 3 twin and Earth whereby the cable runs from a switch and the cable is in the wall and comes outside the brickwork into the junction box where the outside light is connected to it. The cables are all in the little white/clear connection blocks.
    There are 2 neutrals which are in the same slot in a clear connection block however 1 of the neutrals is the grey cable from the house with a blue sleeve over.
    The earths are all in the same slot on another block.
    The permanent live is in another block on its own. Then the live from the outside light is connected to a block with the black cable from the house with a brown sleeve on so I’m guessing that’s only a switch live when the switch is in the ON position.

    My question is can I wire up another light for the side of the house to this point and would it be to the single live or the switch live depending on if I want it to be switched on or off like the other existing light.

    I have a bigger junction box and wago connectors, 20mm conduit piping for the T and E cable and the outside light. Would 1.5mm T and E cable be fine?
     

    Attached Files:

  2. HarryL1234

    HarryL1234 Screwfix Select

    1. If you connect you light to your permanent live, it will be … err … permanently on. Hence use the switched live.
    2. Any cable you run outside has to be fit for purpose — normal twin & earth cable does not necessarily have the UV resistance you require. Armoured cable is a good choice.
    3. Use a weatherproof terminal box and take care to use appropriate weatherproof grommets for cable entries.
    4. If you’re in Wales, outdoor lighting work is notifiable.
    5. As you’re extending an existing outdoor light RCD protection should be in place. But it’s better to check!
     
    Wellwisher likes this.
  3. Wellwisher

    Wellwisher Well-Known Member

    Twin and earth is perfectly OK outside in conduit or pipe as he called it. 1.5mm is oversized for lighting, use 1.0mm
     
  4. Jeffro86uk

    Jeffro86uk New Member

    Thank you for the replies so far.
    To clarify I already have conduit for the cable as I’d read the T and E isn’t UV and weather proof so I’ve gone for 20mm conduit.
    I have a medium sides rectangular shaped junction box which has the rubber gasket seal between the box body and its lid. I was planning on putting silicon beading around the top, sides and entry from the house into the box to get a good seal as Persimmons haven’t done that when they installed it from new build.
    So what cable would be best to connect them, 1 or 1.5mm as I have a reel of 2.5mm given to me. Also the cable Persimmons have installed looks to be 1.5mm if not thicker 3 core and earth.
    Any advice on the best way to seal the pipe into the junction box for the tighter seal? I have 20mm closed grommets at the moment as my intention was to make a small nick into 1 to feed the cable from the light through and only use the conduit for the run of T and E between the existing light and the new one.
     
  5. HarryL1234

    HarryL1234 Screwfix Select

    2.5mm is overspec’d, but it will work.
     
  6. Wellwisher

    Wellwisher Well-Known Member

    1.00 mm is adequate for lights.
     
  7. bright_Spark

    bright_Spark Screwfix Select

    Do you not like 1.5mm?
     
  8. Bazza-spark

    Bazza-spark Screwfix Select

    Can't say I've ever used 1.5 for lights.

    1.0 in domestic, 2.5 in industrial, but never 1.5.
     
  9. bright_Spark

    bright_Spark Screwfix Select

    yes but you are particularly odd
     
    arrow, Ind spark and Bazza-spark like this.
  10. Bazza-spark

    Bazza-spark Screwfix Select

    You have a typo there.

    Should be:

    Yes but you are particularly old.

    :p:D
     
    Ind spark and bright_Spark like this.
  11. HarryL1234

    HarryL1234 Screwfix Select

    Well, the OP has been gifted some 2.5mm T&E. Other than rewiring his house for the hell of it…
     
  12. billysloke

    billysloke Active Member

    What if the new light can turn itself on and off?
     
    HarryL1234 likes this.
  13. Wellwisher

    Wellwisher Well-Known Member

    I don’t like waste.
     
    billysloke likes this.
  14. WH55

    WH55 Screwfix Select

    If I only had some 1.5 or even 2.5, I’d use it. That’s avoiding waste and wasted costs.
     
    HarryL1234 and adgjl like this.
  15. HarryL1234

    HarryL1234 Screwfix Select

    Good point!
     
  16. Jeffro86uk

    Jeffro86uk New Member

    I’ve wired up the light and the cable end into the light but had to stop because of the drizzling rain here so I’ve tucked the exposed end of the cable into the end of the conduit for now until I can get back outside and strip the current junction and fit the new box, wire it all in and job done.
    I’ve used the 2.5mm T and E at present as I wasn’t going to waste it and spend more on cable when you guys said it’d do.
     
  17. bright_Spark

    bright_Spark Screwfix Select

    Me neither, I have wired up all of my lights at my home in 6mm t&e it just makes life easier, I have my shower plugged into a click rose fitting along with my cooker. It makes complete sense.
     
    MrDC, billysloke and WH55 like this.
  18. arrow

    arrow Screwfix Select

    Have never used 1mm for lights always 1.5, Even when using pyro it was always 1.5 specified.
     
    bright_Spark likes this.
  19. Bazza-spark

    Bazza-spark Screwfix Select

    1.5 was always for immersion heaters lol. Never anything else.
     
  20. arrow

    arrow Screwfix Select

    Always used 2.5 for them
     

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