Packages of explosives shall not be unpacked or repacked in a magazine containing over 100 pounds of explosives, nor within 50 feet of a magazine containing over 100 pounds of explosives, or in close proximity to other explosives. Fibre, rubber, or wooden tools shall be used to open cases of explosives, except that non-sparking metal slitters may be used to open fibreboard cases. Opened packages of explosives shall be securely closed before being returned to a magazine.