My utilities room has its own ring circuit protected by a 32A RCBO. The only loads on this ring are a Miele washing machine and a Miele tumble drier, which have been operating just fine for about two years.
This morning, I ran the washing machine no problem. When the wash had finished, I transferred the small pile of clothes to the tumble dryer. I set the tumble dryer going and after about 20s, the RCBO tripped.
I wanted to test whether the RCBO was faulty, so I ran an extension cable from another ring circuit (also protected by a 32A RCBO) and plugged the dryer into the extension cable. 20-30 seconds after switching on, the RCBO tripped.
I'm assuming that since the RCBO trips after almost half a minute, the fault is overcurrent rather than earth leakage.
The filter in the tumble dryer is clear. Any other things I could check to find out what is causing the overcurrent in the tumble dryer?