An RCD or GFCI trips when current leaks to earth. On a coffee machine, that means water and electricity are meeting somewhere they should not.
The common causes
Moisture in the heating element. Elements degrade internally and admit moisture, creating a leakage path. This is the commonest cause and it gets worse, not better.
Condensation after storage or transport. A machine brought in from the cold, or unused for months, can trip once and then behave normally after drying out.
Water where it should not be — a leaking boiler, a split hose, a cracked seal dripping onto wiring.
A failing thermostat or thermal fuse.
What to do
Do not simply reset and carry on. The RCD is doing its job.
Unplug it and leave it somewhere dry and warm for 24 to 48 hours. If it was condensation, it will stop.
If it trips again, stop using the machine and have it looked at. A leaking element is a shock risk.
Testing safely
An electrician or technician can measure insulation resistance between the element and earth. This is a definitive test and it is not a DIY one on a mains appliance.
The circuit
Espresso machines draw 1,200 to 1,500 W. A shared circuit with a kettle and a toaster can trip a breaker on overload — that is a different fault, and it presents as tripping only when several appliances run.
An RCD tripping on the machine alone is leakage, not overload.
The rule
Overload can be managed. Leakage means service.
Last reviewed 8 August 2026