The quick verdict
A Cosmo dishwasher that trips its protection should be switched off at the consumer unit and left off. This is the appliance where water sits closest to the electrics, and a machine that trips on the heating phase is usually telling you the element has failed to earth. Nothing below asks you to open anything that should stay closed.
The observables
- A tingle from the door or the front panel — Current is reaching metal you can touch. Give it a moment rather than glancing; the thing you are looking for is not always obvious.
- A hot or burning smell during the cycle — In a wet appliance a burning smell is a fault, not a smell. Compare it with how the machine behaved a month ago rather than with how you expect it to behave.
- Heat marks or browning at the plug or connection — A poor connection heating under load, which is a fault in its own right regardless of the machine. Note the result even if it is negative, because a ruled-out cause is progress.
- Water under the machine as well as a trip — The two usually travel together, and the water is normally the cause rather than the coincidence. Note whether it happens every time or only sometimes, because that distinction narrows the list.
Causes, most likely first
- A heating element that has failed to earth — First because the element sits in water by design and because its failure produces the classic trip a few minutes into every cycle. Write it down before anybody comes out; a described symptom is worth more than a remembered one.
- Water reaching a terminal, connector or the motor — Second because a built-in machine leaks into its own cabinet unseen, and the electrical symptom is often the first visible sign. A cause in this position is worth eliminating before you spend anything.
- A door switch or wiring chafed by the hinge — The harness that crosses a moving joint flexes every time the door opens, and insulation eventually wears through. That single observation eliminates more of the list than any amount of guessing.
- A shared or undersized circuit — An installation fault rather than an appliance one, but the symptom at the consumer unit is identical. This is the cause people skip, and skipping it is why the diagnosis takes three visits.
What to look at first, second, third
- Inspect the plug, socket and cord where you can reach them — Discolouration or melting means that connection needs attention whatever else is true. Nothing below this line is worth chasing until this one is ruled out.
- Check whether anything else shares the circuit — A circuit already near its limit trips without any appliance being faulty. A result here decides whether the next two checks are worth doing at all.
- Try one cold or rinse-only programme — If a cold programme completes and a heated one trips, the heater is the obvious suspect. Do this once only. Nothing below this line is worth chasing until this one is ruled out.
What an owner can safely check
- Dry the floor of the housing and look for the source — A torch along the base of the cabinet shows standing water and the track it came from. The value is in eliminating, not confirming; most of these come back negative and that is useful.
Tools: torch, towelAbout 20 min
- Write down the exact circumstances of the trip — Programme, elapsed time, which device tripped, and anything you could smell. Take a photograph before you disturb anything you will have to reassemble.
About 10 min
- Leave the machine off until it has been looked at — Leave the breaker off rather than relying on nobody using it in the meantime. If you can only do one check, make it this one.
About 5 min
- The last owner step is the one above this line — That is the boundary between a homeowner check and a service call, and it is not a soft one.
What has to be off
Safety
Disconnect the machine from the mains before any part of this, without exception. Stored charge does not drain the instant the supply stops. Do not run a cycle to test something while the machine is open or pulled out of its housing. Leave the door switch wired exactly as you found it; it is a guard and not an inconvenience.
The handover point
Draw the line here: the owner side of an electrical fault ends at the breaker switch, and that is where it should end. It is not about difficulty; it is about what happens when something goes wrong. Call rather than improvise if the machine has to come out of a fitted housing to reach the fault.
Pages alongside this one
What this page does not cover
Scope note: this page addresses the dishwasher as a class of machine under the Cosmo badge.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
