General smoke detectors shall be installed in all residential dwellings containing two or more dwelling units. Installation of such a system or device shall be for the purpose of early warning of the presence of smoke and/or fire to the occupants of residential buildings and shall conform to the installation, maintenance and use of household fire warning equipment guidelines as set forth in the National Fire Protection Association Publication (N.F.P.A.), 1978 edition, specifically N.F.P.A. 74-1978 and N.F.P.A. 72-1978, subsection (E) and all appendices pertaining to the subsection contained therein and shall comply with Level Four of N.F.P.A. 74-1978. (Ord. 1302-83. Passed 6-18-83.)