Mechanical protection doesn't relate to EN50131 that would be covered under BS7671 and all connection boxes must be tampered at any Grade above 1. Masking is obviously a Grade 3 requirement.
All the standards are there but they are copyright protected you purchase them from the BSI website, your company should have a copy.
The best you will get without reading the standards is the manufacturers quick guides that are about, I think the Castle one is in the Downloads section.