Whoever operates or employs any person to operate any crane, derrick, power shovel, drilling rig, pile driver, or like apparatus, any part of which is capable of vertical, lateral, or swinging motion, without there being posted and maintained in plain view of the operator thereof a durable, weather-resistant warning sign legible at 12 feet, reading "WARNING, unlawful to operate this equipment within 10 feet of overhead high voltage lines," is guilty of a misdemeanor and, upon conviction, shall be fined not more than five hundred dollars ($500) and imprisoned for not more than 12 months, or both fined and imprisoned. Each day's failure to post or maintain such a sign shall constitute a separate offense.