If a person lives in a part of city further from where he works, let’s say 2-3 hr journey and commutes to work, does he have to pray/break his fast following prayer time of where he is working? Or following prayer time of where he is residing? If magrib is at 5.30 at his work place and 5.35 at his residing place, can he break fast at 5.30 if he is still at work or wait until 5.35?

if a person is committing daily of even 5 days a week he has to fast at his work place and offer his salat full not broken. but as for as timing of salat concern he has to follow the local time for his salat and for opening his fasts.