What is the device doing?
RCDs and RCBOs are protective devices. They disconnect the supply when they detect certain fault conditions. If one keeps tripping, the answer is not to keep resetting it indefinitely. The cause needs to be found.
Common causes
Typical causes can include damaged cables, water ingress, faulty appliances, outside electrics, heating elements, poor connections, neutral-to-earth faults or a fault that only appears when a particular item is switched on.
Why it can be difficult to diagnose
Some faults are constant and easy to reproduce. Others are intermittent, moisture-related, appliance-related or only appear under load. Proper testing and a methodical approach are usually needed.
What should you do?
Make a note of what was on when the tripping happened, whether it affects one circuit or several, and whether any outside equipment, heating, kitchen appliances or extension leads were in use. Then arrange proper fault finding.
Safety note
Do not bypass, tape up, defeat or repeatedly force a protective device to stay on. If it keeps tripping, there is a reason.