1. In every multiple dwelling the owner shall provide a light or lights, each of at least sixty watts incandescent or twenty watts cool white fluorescent or equivalent illumination, for every vestibule and entrance hall in every public hall, stair, fire-stair and fire-tower on every floor. Said light or lights shall be located as prescribed by the department, but, in every stair, fire-stair or fire-tower, shall be so located that every part thereof shall be lighted.
2. Except as provided in subdivision three, every such light shall be turned on by the owner at sunset every day and shall not be turned off by the owner until the following sunrise. Every such light shall be kept burning daily from sunset until sunrise, but if it becomes extinguished and remains so without the knowledge or consent of the owner he shall not be liable. The burden shall be upon the owner to show that the light became and remained extinguished without his knowledge or consent.
3. Every light in every fire-stair and fire-tower at every story, and in every stair and public hall at every story where there is no window opening to the outer air, shall be kept burning continuously except that this provision shall not apply to public halls lighted as provided in subdivision eleven of section two hundred seventeen.
4. When the natural light in any public hall in a multiple dwelling is not sufficient to permit a person to read the names on a mail box or other receptacle for mail, the owner shall install a lighting fixture directly over such mail box or receptacle and maintain it in serviceable condition, so that a light may be turned on at any time for the convenience of tenants or the mail carrier.