How to attach electrical boxes to Leca???

[Starfighter]

I was thinking of adding recessed electricity to my cinder block garage, but I'm having trouble securing boxes and conduits. How do you make them stay in place properly???

Nails don't work even if I use long, thick ones, and screws don't grip the cinder blocks unless you go up to a size that damages the boxes, and even then it's not really good. Someone suggested PL400 or something similar, but I think it doesn't adhere well to the cinder blocks, or am I wrong...? Any other tips?

 

[Tidde]

pl 400 sticks to everything but screws and plugs also work that's what I do anyway.

 

[anaitis]

Foam, little dabs, they expand!

 

[Bergling]

Or Husfix. That works well too.

 

[Milkshaken]

PL400 helps