Response at this date may not be helpful, but here goes.
This is a somewhat open-ended question.
The first obvious response is that it depends on the particular standard -- in other words....maybe not...
British Standards that are currently in place, are obviously valid for British installations. However, in other European Community countries, those standards are without merit. Each country may have different methods. This is why harmonized standards are utilized. If in doubt, utilization of the relevant EN would be advised.