Heater keeps tripping the breaker
A plain-English first check for temporary heaters that trip a breaker, including load, circuit sharing and cable red flags.
Quick answer
Do not keep resetting a breaker so a temporary heater can stay on. A trip is a sign that the load, circuit sharing, appliance condition, RCD behaviour or cable route needs checking before the setup is used again.
Typical example
A 3 kW heater is already about 13.0 A at 230 V. Add a dehumidifier, fan, till, charger or office kit on the same circuit and the total can move past the selected rating or warning point very quickly.
First thing to check
Add every item that runs at the same time. Include background loads people forget: chargers, monitors, small pumps, fans, lighting, tills and anything plugged into the same confirmed circuit group.
Trip pattern clues
A trip when the second heater starts often points to overload. A trip in damp conditions, after a lead is moved, or from an RCD may need a different check. A warm plug, damaged lead or wet route is a stop-condition issue, not just a calculation problem.
What to change
Reduce wattage, stagger heaters, move loads only onto confirmed separate circuits, remove adaptor chains and avoid coiled reels. Do not treat a different nearby socket as separate until it has been mapped.
Handoff note
Send the trip pattern, equipment watts, what was running together, socket/circuit rating, extension lead details and any visible damage to a competent electrician, responsible person or hire supplier. The breaker trip triage tool creates this note for you.