Except as otherwise provided in Section 15.148.290 of this chapter, no sign or any other portion thereof shall be allowed that moves or assumes any other motion constituting a nonstationary or fixed condition except for the rotation of revolving prism units in off-site signs or billboards. Revolving prism units may be used if such parts do not exceed a speed of one complete revolution, including the stationary condition of the prisms, in a thirty (30) second period. (Ord. 2016-0010 § 30; prior code § 3.08.154)