Any owner or owner’s agent may enter any dwelling unit or guest room owned by such owner for the purpose of inspecting, repairing, testing, and maintaining smoke detectors required by Chapter 9 of the Los Angeles Municipal Code (Building Code). Except in cases of emergency, the owner or owner’s agent shall give the tenant reasonable notice in writing of the intention to enter and shall enter only during normal business hours. A period of 24 hours shall be considered to be reasonable notice in the absence of evidence to the contrary.