Get yourself one of these & add a padlock to which you have the only key.
http://www.screwfix.com/p/brady-mini-circuit-breaker-lockout-system/6514f
!
Another thing I do if working on older systems with cartridge fuses or rewirable fuses is to remove the fuse & keep it in my pocket.
that's it in a nutshellI just use Knippex side cutters, alltho when working on cars I have some ancient adjustable things that are good for a tight spot