Sat here this morning watching TV and power went off. I investigated and saw the breaker on one side of the panel had tripped. It would not reset. That side of the board was outside power (spare 10), burglar alarm ( now unused),lights first floor, sockets and shower. It’s the RCD that keeps tripping. Next I removed all appliances and it still wouldn’t work. I then tested each circuit individually. All circuits were fine. I then tried the power sockets on its own. It held. I then started to plug things in. First item tripped it. Removed the appliance and reset. Plugged another one in it too tripped it. This happened for every single different appliance plugged in. No more than one item at a time. Could the RCD be faulty?