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 http://www.wickes.co.uk/Aquapanel-Ce...-40mm/p/224585

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.