The payment or granting of compensatory time off in lieu of payment as prescribed in sections 81-117 to 81-117.02 shall not apply to (1) agency heads, their deputies and assistants, (2) chiefs of divisions, bureaus, or comparable organizational elements, and (3) other professional, executive, and administrative employees occupying classes of positions that by custom in business, industry, and other governmental jurisdictions are normally exempt from receiving overtime pay and may require the individual to work extra and irregular hours and that acceptance of such position constitutes the employee’s acknowledgment that such requirement is a part of an obligation to the state as an employee thereof. The term deputy as used in this section shall not apply to the deputy state fire marshals or deputy state sheriffs.