Question

Is it permissible for those who do hard work to break the fast during Ramadaan, such as those who work in foundries and factories and do other kinds of hard work?.

Praise be to Allah.Some scholars have issued 
    fatwas saying that it is permissible for these people not to fast. I sent 
    the fatwa to Shaykh ‘Abd-Allaah ibn Muhammad ibn Humayd and Shaykh ‘Abd 
    al-‘Azeez ibn Baaz (may Allaah have mercy on them) for their comments on it 
    and they said:  

    The basic principle is that it is obligatory to fast 
    Ramadaan, and to form the intention to fast from the night before, for all 
    adult Muslims, who should start the day fasting, except for those to whom 
    the Lawgiver has granted a concession, who are allowed not to fast – namely 
    the sick, travellers and those who come under those headings. Those who do 
    hard work come under the heading of those who are obliged to fast and they 
    are not like the sick or travellers. They have to form the intention to 
    observe the Ramadaan fast from the night before, and to start the day 
    fasting. If one of them is forced to break the fast during the day, then it 
    is permissible for him to break the fast with enough to ward off any harm, 
    then he must refrain from eating and drinking for the rest of the day, and 
    he has to make up that fast at the proper time. If there is no such 
    necessity then it is obligatory to complete the fast. This is what is 
    indicated by the shar’i evidence from the Qur’aan and Sunnah, and it is what 
    is indicated by the words of the scholars of all madhhabs. 

    Those in positions of authority among the Muslims among whom 
    are people who do hard work should examine their case when Ramadaan comes, 
    and if possible, they should not burden them with too much work that may 
    force them to break the fast during the day in Ramadaan, rather they should 
    have the work done at night, or distribute work hours in a fair and just 
    manner so that people may both work and fast. 

    As for the fatwa referred to, this has to do with an 
    individual case where they issued a fatwa based on their ijtihaad for which 
    they are to be appreciated, but they did not mention the conditions that we 
    have mentioned or the view of the scholars of all madhhabs. We ask Allaah to 
    help us all to do that which is good. End quote. 
Shaykh ‘Abd-Allaah ibn 
    Muhammad ibn Humayd (may Allaah have mercy on him). 

    Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allaah have mercy on 
    him). 

    Majmoo’ Fataawa Ibn Baaz, 
    14/245 

    And Allaah knows best.