Heres a tip that I self discovered.
I find that when I nail plastic capping to masonry wallls to cover cables, three things happen.
either the masonry nail bends
or the mortar is so soft that the nail wiggles loose.
or the nail head is so small that the plastic capping pops off
I have a solution.
I use ceramic coated screws... offer up capping to the masonry walls, use an electric screw driver to screw ceramic coated screws through capping into a mortar course... No pre drilling or plugging with rawlplugs is needed.
The cermic screws are originally marketed for use with Aquaboard, they are ceramic coated so that they can screw through the aquaboard without pre drilling.
See
Be warned that Wickes are stopping selling these so you will need to find a new source.
I use a battery powered screw driver on these screws to fix capping to the mortar courses in walls.... no more brusied thumbs/fingers, no bent nails, no loose nails etc.
If you have celcon or thermalite blocks, the screws can be screwed straight into the blocks as well as the mortar course.
If you really need to screw into hard bricks or into really hard mortar just drill a small pilot hole of say 3 diameter then screw said screws into it.