ᐅ Size of Core Drill Holes for 68mm LED Recessed Downlights

Created on: 21 Jun 2017 20:36
J
Jazz089
Dear forum community,

We would really like to have recessed ceiling lights in our new build (precast concrete slab), but the installation of flush-mounted sockets by our general contractor was very expensive (1 spot / 185€) and somehow we missed the deadline...

After discussing with our general contractor, the suggestion was made to possibly drill core holes for the spots afterward. We now want to first talk to the structural engineer to see if that is even possible. However, we assume it will work.

My husband visited a lighting designer today, who said that a 68mm (2.7 inches) core hole for 68mm (2.7 inches) spots would probably not be sufficient, because the LED lights would get too hot in such a small hole and there would be no air circulation for cooling. According to him, the LEDs would fail almost weekly due to the heat in this setup. Therefore, holes of at least 20cm (8 inches) would need to be drilled. We are now very uncertain and don’t know what to do. Do you have any experience with this? We would be very grateful for any advice. Channels for cables would not need to be milled since the electrician would run the cables from above into the spots (upstairs).

Thank you for your help, and as mentioned, we look forward to your feedback!
J
Jazz089
2 Jul 2017 09:55
We were thinking of about 35 recessed lights. Yes, the core drillings were supposed to be done from below, and then the electrician would have come from above to do the wiring. So it would have been just a small hole.

After several consultations with various lighting specialists and our construction company, core drilling is questionable. It could be done, but they wouldn’t be allowed to be aligned in a row. In other words, that would look completely impractical. Also, we would really need the larger drilling because these get hot. I’m quite disappointed that it’s unfortunately not going to work out with the recessed lights. We will partially lower the ceiling, but not too much, since we only have a ceiling height of 2.40 m (7 ft 10 in). Due to the central ventilation system, we have lost another 8 cm (3 inches). I guess I’ll just have to live with it. With the partially lowered ceilings, we will still be able to install indirect lighting. That’s my consolation :-((((
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nelly190
2 Jul 2017 14:11
Over the weekend, I installed the new Ikea light panels at a friend's newly built house. They are a great alternative to recessed lights. They come in three sizes:
30 x 30 cm (12 x 12 inches)
60 x 60 cm (24 x 24 inches)
90 x 30 cm (36 x 12 inches)

They provide awesome, even lighting. In my own home, I have mostly used recessed lights.