Start at the DB board: what a trip is actually telling you
Every UAE home has a distribution board (DB), usually a grey or white panel near the entrance or in the corridor. Inside sit a main isolator, one or more RCDs (residual current devices, the wide switches with a test button) and a row of MCBs, the small breakers that each protect one circuit: kitchen sockets, bedroom sockets, lighting, the water heaters, the AC units. When something trips, which switch went down tells you most of the story before anyone picks up a phone.
UAE boards have a few local quirks worth knowing before trouble starts. Water heaters usually have their own switches, sometimes on the board and sometimes on the bathroom wall, and each split AC unit typically has a dedicated isolator. Older flats often carry a second small board for the heaters alone. Ten minutes spent flipping breakers one by one and writing what each controls on the board's door turns your next fault call from a vague description into a precise one, and shortens the electrician's paid diagnosis time accordingly.