Section 58D. The hours of duty of the permanent members of the uniformed fire fighting force in every city and town in which this section is accepted as hereinafter provided shall be so established by the fire commissioner, board of fire commissioners, chief engineer, board of engineers, or other officers having charge of fire fighting that the average weekly hours of duty in any year, other than hours during which such members may be summoned and kept on duty because of conflagrations, shall not exceed forty-two in number; provided, that any such city by ordinance and any such town by by-law may establish such weekly hours of duty at less than forty-two. Sections fifty-six, fifty-seven, fifty-eight A, fifty-eight B and fifty-nine shall not apply to the permanent members of the uniformed fire fighting force in any such city or town.

This section shall become effective in a city having a Plan D or Plan E charter when accepted by a majority of the members of the city council, and, in the case of other cities, by vote of the city council and the approval of the mayor, and in a town by a majority vote at the annual town meeting, or in any city or town in which the question of adopting this section is placed before the voters thereof, in the manner set forth in the following paragraph, and a majority of the voters voting at such election vote in the affirmative on such question.

Upon petition of not less than five per cent of the registered voters in any city or town, duly certified by the registrars of voters and filed with the state secretary not less than sixty days before a state election, or filed with a city or town clerk not less than sixty days before a municipal election, the state secretary, or the city or town clerk, as the case may be, shall cause to be printed upon the official ballot to be used in such city or town at such state or municipal election the following question:—''Shall section fifty-eight D of chapter forty-eight of the General Laws, providing for a forty-two hour work week for permanent members of fire departments, be accepted?'' If a majority of the votes cast on said question in any city or town are in the affirmative, this section shall take effect in such city or town ninety days thereafter.