Friend has 1 mtr high railway sleeper retaining wall with gravel behind it.

She wants 9 plastic bulkhead type lights 240 volt, 17 watt on it with the wiring hidden so drill through sleepers and run my guess 1.5 mm 2 core SWA with the armour bonded together buried say 200 mm below surface with some scare tape.

Therefore two SWA glands going in and out of each fitting.

Total load will be 153 watts.

Length of cable to house consumer unit say 20 mtrs.

Am I over the top using SWA just in case someone puts a shovel through it or is there an easier type cable to use but still needing some sort of weather protective gland or will sealer do the job.

It will be going through a spare RCD way.

Thanks guys