Motion sensor in the concrete ceiling (flush-mounted)

Hello,

I would like to install a motion detector (flush-mounted) in our concrete ceiling. The cable has been laid with an empty conduit, but no box was installed. Can I install a box afterwards, or is it a bad idea to drill into the concrete ceiling with a hammer drill?

Regards

Tichu78

The idea is not bad, but it is a material-fatiguing job to drill through the concrete ceiling. I would rather install a discreet surface-mounted motion detector, similar to a smoke detector.

Something like that? Well .. subtle is relative ;) Unfortunately, I have no experience with how precisely you can hammer a hole in concrete. If you hit steel, it's over anyway, right?