Defines safety requirements and their verification for designing and constructing screw splitters with horizontal screws, for one operator for splitting wood, regardless of power source used. With dual purpose circular saws for firewood/log splitting machines, only the log splitter part is addressed for circular saws. Methods are outlined for reducing or eliminating risks from using them, as well as defining the type of information on safe working practices to be provided by the makers. A list of important hazards dealt with is covered in annex A.