Employees whose work means that they have to continue working at the time of Jumu’ah
Question

                Some sensitive jobs require the constant presence of an employee, including at the times of obligatory prayers and Jumu’ah (Friday) prayers. Should these employees leave their work and go and pray, or should they stay on the job?
Praise be to Allah.
    The basic principle is that Jumu’ah prayer is obligatory upon 
    individuals, because Allaah says (interpretation of the meaning): 

    “O 
    you who believe (Muslims)! When the call is proclaimed for the Salaah 
    (prayer) on Friday (Jumu‘ah prayer), come to the remembrance of Allaah 
    [Jumu‘ah religious talk (Khutbah) and Salaah (prayer)] and leave off 
    business (and every other thing). That is better for you if you did but 
    know!”

    [al-Jumu’ah 62:9]
And Imam Ahmad narrated 
    from Ibn Mas’ood (may Allaah be pleased with him) that the Prophet  
    (peace and blessings of Allaah be upon him) said concerning some people who 
    were failing to attend Jumu’ah prayers: “I had thought to tell a man to lead 
    the people in prayer, then I would burn down the houses of men who fail to 
    attend Jumu’ah prayers.” (Ahmad, 1/402; Muslim, 1/452). Muslim narrated from 
    Abu Hurayrah and Ibn ‘Umar (may Allaah be pleased with them) that they heard 
    the Messenger of Allaah  (peace and blessings of Allaah be upon him) say 
    from the minbar: “There are people who should stop neglecting Jumu’ah, or 
    else Allaah will put a seal on their hearts, then they will surely be among 
    the negligent.” And there is consensus among the scholars on this point 
    (that Jumu’ah is obligatory). But if a person for whom Jumu’ah is obligatory 
    has a legitimate shar’i excuse – such as one who is directly responsible for 
    a matter of national security and protecting the interests of the ummah, and 
    he is required to do that job at the time of Jumu’ah, such as those who are 
    in charge of security, traffic, wireless and telephone communications, etc, 
    those whose shift happens to be at the time of the second call to Jumu’ah 
    prayers or the time of a prayer in congregation – then such people are 
    excused for not praying Jumu’ah or prayers in congregation, because of the 
    general meaning of the verse (interpretation of the meaning): 
“So keep your duty to 
    Allaah and fear Him as much as you can”
[al-Taghaabun 64:16]
And the Messenger of 
    Allaah  (peace and blessings of Allaah be upon him) said: “Whatever I 
    forbid you to do, avoid it, and whatever I command you to do, do as much of 
    it as you can.” Moreover, such a person has no less an excuse than one who 
    is excused because he fears for his life or his wealth etc., who the 
    scholars have said is excused for not praying Jumu’ah or prayers in 
    congregation so long as the reason is present. But the obligation to pray 
    Zuhr still stands, and he must pray it on time; whenever he can pray in 
    congregation he is obliged to do that, as is the case with all the five 
    daily obligatory prayers.