(a) The requirements of this article shall apply to all parks, accessory buildings or structures, and units, (except within permanent buildings), in all parts of the state, to the construction, installation, alteration, repair, use, and maintenance of all electrical wiring and equipment for supplying electrical energy to all units.

(b) Existing electrical construction, connections, and installations made before the effective date of the requirements of this chapter may continue in use so long as they were in compliance with requirements in effect at the date of their installation and are not found to be substandard.