As used in this section and sections twenty-six E and twenty-six F the following terms shall have the following meanings unless the context clearly indicates otherwise:
"Approved monitored battery power smoke detector", shall be a smoke detector which is activated by a battery power source provided that the battery is monitored to assure that the following conditions are met:
"Approved primary power smoke detector", shall be a smoke detector which is activated by being permanently wired to a source of alternating current electric power or connected to a source of alternating current electric power by an underwriter's laboratory approved cord with a strain relief and plug retainer; provided, that:
"Common hallway", a common corridor or space separately enclosed which provides common access to the required exitways of the residential building or structure.
"Separate sleeping area", shall mean the area or areas of the dwelling unit in which the bedrooms, or sleeping rooms, are located. Bedrooms, or sleeping rooms, separated by other use areas such as kitchens or living rooms, but not bathrooms, shall be considered as separate sleeping areas.
Mass. Gen. Laws ch. 148, § 26D