Core drill sizes for 68mm LED spots

Dear forum community,
we would really love to have ceiling spots in our new build (filigree ceiling), but the installation of the flush-mounted boxes by our general contractor was way too expensive for us (1 spot / 185€) and somehow we also missed the boat....

After consulting with our general contractor, the suggestion came up to possibly drill core holes for the spots afterwards. We now want to talk to the structural engineer first to see if this is even possible. But we assume that it will work.

Today my husband was at a lighting planner, and he said that a 68 mm core hole for 68 mm spots probably wouldn’t be enough because the LEDs would get too hot in such a small hole and there wouldn’t be any air around to cool them. The LEDs would almost break weekly due to the heat in this setup. Therefore, we would have to drill holes at least 20 cm in size. We are now very uncertain and don’t know what to do. Do you perhaps have any experience with this matter? We are very grateful for any tips. Schlitzes wouldn’t need to be milled, by the way, since the electrician would lay the cable from above into the spots (floor above).

Thank you for your efforts and as mentioned, we are looking forward to your feedback!

We have installed Kaiser HaloX cans, diameter 160mm. So I think that should be sufficient as a core drill hole. But that is just my opinion.

Thank you for your quick reply. Well, you have 16cm then... we would only have just under 7cm, or otherwise drill 20cm, which might not be so simple with the statics....

I think the statement is nonsense. The LED is cooled via a heatsink in the lamp itself. Whether it is somewhere under a drywall ceiling or in a concrete hole doesn’t really matter to it. Even powerful spots are at 7 watts, most of which is converted into light, so there isn’t that much left for heating. I find the question more interesting of how the sockets are supposed to be fixed in the hole. Normally they require some layer like drywall to clamp onto.

1. A larger borehole than, for example, 70 mm is definitely needed. Even though the LED spots emit relatively little heat, it is still enough to make it very, very hot if there is no convection at all. (Tested myself with LEDON 6 W lamps) 2. Core drilling into the reinforced ceiling is most likely not permitted.

How many spots will there be? We have almost 30 on the ground floor (also in these Halox boxes).

Do you want to drill through the entire ceiling so you can cable from above? I really can't imagine that the statics can handle that.
There is at least still some steel on our Halox boxes..

I also believe that LEDs get too warm. There is quite a bit of air around them in the boxes.