OSHA says hard hats for the head protection of employees exposed to high voltage, bumps, falling debris,electrical shock and burns should be a normal practice of work place safety. ANSI Type I / CSA Type 1 hard hats meet stringent vertical impact and penetration requirements for hard hat safety. ANSI Type II / CSA Type 2 hard hats meet both vertical and lateral impact and penetration requirements and have a foam inner liner of expanded polystyrene. A Class E hard hat has been proof-tested to insulate up to 20,000 volts of electrical potential hazard.