Installing down lights and drilling roof trusses/beams??

Discussion in 'General Chat' started by Arcam_boy, Jun 15, 2015.

  1. Arcam_boy

    Arcam_boy
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    Hello.

    We're looking at freshening up our kitchen/diner and as part of that I want to install 6 down lights in the dining area and 6 in the kitchen area.

    I've just spent an hour making them all out and checking these avoid the beams in the roof.

    To run the cables I'll somehow need to get the cables through the joists which will require a 20/30mm hole to feed the cable through.

    I've had a quick look on-line and seen a few suggestions about removing the floor above to get access, however if this was the only option I'll can the idea now as it would mean pulling up a carpet in our bedroom and removing wooden flooring in another bedroom before we even began looking at removing the actual floor boards.

    Now I don't want to belittle the job, but some of the quotes I've had back on mybuilder are ridiculous and would take me 3 - 4 days to earn what they want to install the lights.

    So my question is....

    Can I drill the big beams to feed an electric cable through? I've seen online it recommends drilling dead centre of the beam to avoid screws/nails going in to the cable in the future? If not any other suggestions??

    Thanks
     
  2. SteveCritten

    SteveCritten
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    I am doing this in my kitchen soon my joists have gaps anyway but my only alternative is to remove the existing ceiling do the wiring then re board and skim :(.
     
  3. Digital Tench

    Digital Tench
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    How are you going to drill these holes without removing the floorboards?

    The hole you drill needs to be 50 mm from the top AND bottom of the joist, otherwise a RCD or mechanical protection (such as using armoured cable) would be needed to be compliant for Part P (you will be modifying the existing wiring so this will need certifying and I can assure that surveyors and homebuyers are very quick to ask for certifications for down-lighters (mainly because they are installed badly (cause fires and / or weaken joists etc). Please note I am not taking a pop at you here.

    Maximum hole diameter and where you can drill the holes along the span (and how far apart) are also specified by building regs (Part L) - you should be able to search for them online.

    If there's a living space above you will moist probably need fire rated down-lighters as well.
     
  4. Digital Tench

    Digital Tench
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  5. Arcam_boy

    Arcam_boy
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    Thanks for the replies.

    I'm happy for any information/advice and certainly won't see it as you taking a pop mate. I'd rather be told than just crack on and the house falls down!

    With regards to drilling the hole...

    A junction box is going to have to be fitted to each 6 set of lights within the ceiling void so I was going to make a hole in the roof to fit this and use the hole to fit my drill through and drill the joist either side to feed the cable through? Then board it up as the roofs going to be skimmed over once the electrics are sorted.

    I've had a look at the fire rated downlights with LED bulbs and plan to use those.
     
  6. FZR400RRSP

    FZR400RRSP
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    When we got downlights installed in the kitchen, there was no drilling for the cables.
    The electrician basically cut small 'checks' (slots) out of the beams just enough for the cables to slip into and still clear the ceiling.
    So we ended up with around half a dozen small holes in the ceiling for the 'checks', which were easily filled/skimmed painted.
    No big holes needed to the beams to get a drill into etc.
     
  7. Digital Tench

    Digital Tench
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    Junction boxes will need to be maintenance free and standard JB's absolutely need to be screwed to the joist. Personally I'd use the Line range of egg shaped MF JB's and Wago MF connectors. I'd also use the method FZR's sparks used to install (with the protection plates I linked to). It'll still be notifiable work mind and some surveyors always check!

     
  8. IronGiant

    IronGiant
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    With that method how do you feed the cable? can you do the whole job like "keyhole surgery" ? Impressive if you can, you've got me thinking now :) .
     
  9. Digital Tench

    Digital Tench
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    The Line MF boxes I mentioned can be fed through and surprisingly small hole and don't need to be fixed to a joist (they use cable ties to ensure connections are not excessively pulled.

     
  10. IronGiant

    IronGiant
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    Thanks, have you got a link to those ? I have a light in a flat roof extension that I'd like to move a few feet and Sod's law dictates it's across the joists and not between them. I've been kicking myself that I didn't get it done when I had the roof replaced last year and could have accessed from above :facepalm:
     
  11. Digital Tench

    Digital Tench
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  12. IronGiant

    IronGiant
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    Thank you !!
     
  13. Arcam_boy

    Arcam_boy
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  14. Digital Tench

    Digital Tench
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    No problem at all!
     
  15. WeegyAVLover

    WeegyAVLover
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    @Arcam_boy - what FZR said with those safety plates
     
  16. Arcam_boy

    Arcam_boy
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    I've just finished installing the 6 lights for the dining room section and must say those Wago connectors are bloody brilliant. :clap:

    I was pretty fortunate with the cable run in the end and managed to use the existing holes in the beams to also feed my cables through so I didn't have to cut or drill the beams at all. I just had to cut two small access holes (you might just be able to see them in the picture) so I could get my hand in the feed the cables through and that was it!

    Took me around 2 hours altogether to install the first 6 but I was doing it fairly leisurely and I'll happily give up four hours of my time to save myself £300!

    I've not mounted the lights fully in to the roof yet as once I've done the other 6 I need to remove them so the ceiling can be skimmed and then I'll get an electrician to sign off the wiring before installing the lights fully in to the ceiling. :thumbsup:
     

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