Electrical faults can have several possible causes, so an accurate diagnosis normally comes before a repair. Describe what happens, when it started and which circuits or rooms are affected. If there is smoke, fire or immediate danger, leave the area and contact the emergency services.
When to enquire
Define the scope
How faults are traced
Fault finding is a process of narrowing down, and the most useful information comes from the person who lives there. When it happens, what is running at the time, which rooms are affected, whether it is worse in wet weather — that pattern targets the testing and shortens the job considerably.
Most domestic faults fall into a small number of categories: an appliance leaking to earth, water reaching a circuit, a loose or failed connection at an accessory, a damaged cable, or a circuit overloaded beyond what it was designed for. Which one it is determines whether the fix is a repair, a replacement or a redesign.
The quickest test is elimination: unplug everything on the affected circuit, reset, then reconnect one item at a time. If it holds until a particular appliance runs, that appliance is the cause. If it trips with nothing connected, the fault is in the fixed wiring.
Note the date, time, what was running and the weather each time it happens. That log genuinely shortens diagnosis because testing can be targeted at the conditions that reproduce the fault.
A device that trips immediately on reset is reporting a live fault. Repeated resetting on a real fault is how damage and fires start. Leave the circuit off and have it investigated.
Insulation resistance and continuity testing locate a fault that cannot be seen. Guesswork replaces accessories that were never the problem, which is why testing is usually cheaper than trial and error.
Include the postcode, preferred timing and any useful existing information.