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REFRIGERATION

Troubleshooting

MCB or RCCB tripping when the fridge starts

A breaker that trips as the compressor starts is warning you of a real electrical problem, so it should never be bypassed or replaced with a higher rating to make it stop. First identify which device trips. An MCB (miniature circuit breaker) trips on excess current: an overloaded circuit, a short circuit or a compressor that draws a huge current because it cannot start. An RCCB or RCBO trips on earth leakage: current escaping to earth through damp insulation, a damaged cable or a faulty heater or motor. Leakage can give someone a shock, so treat RCCB trips seriously. Both need an electrician or refrigeration technician to fix, but a few checks help them.

First, check these

  1. Note which device tripped: an MCB for that circuit, the RCCB for a group of circuits, or a combined RCBO.
  2. Note exactly when it trips: the moment the unit is plugged in, when the compressor tries to start, during defrost, or after cleaning.
  3. Unplug other appliances on the same circuit and try once. If it then holds, the circuit is overloaded.
  4. Check the cord, plug and socket for damage, scorching or water. Do not use it if you find any.
  5. Think back: was the unit cleaned with a hose or wet mop, or has monsoon water reached the area recently?

Likely causes

  1. 1. Circuit overloaded with other equipment

    You can check this

    Signs: MCB trips only when the refrigerator starts while other heavy loads such as microwaves, kettles or ovens are running.

    Fix: Move the refrigerator to a socket on its own suitable circuit. An electrician can confirm the circuit design.

  2. 2. Moisture in wiring or components

    Technician job

    Signs: RCCB trips after wet cleaning, during heavy rain or in very humid weather, then works once dry.

    Fix: Isolate power and let the unit dry with good ventilation. Avoid hosing or splashing machine compartments. If it recurs, a technician should find the wet component.

  3. 3. Defrost heater or fan insulation failure

    Technician job

    Signs: RCCB trips at the start of defrost or when a fan starts.

    Fix: A technician tests each component's insulation and replaces the faulty heater or motor.

  4. 4. Compressor locked or windings shorted

    Technician job

    Signs: MCB trips the instant the compressor tries to start; humming then trip, sometimes a burning smell.

    Fix: A technician checks starting components and winding resistance and insulation. A shorted or grounded compressor must be replaced.

  5. 5. Breaker not suited to motor starting

    Technician job

    Signs: New installation; MCB trips at start even though the unit runs well on another circuit.

    Fix: An electrician should check that the breaker rating and tripping characteristic suit a motor load and the cable size. Never just fit a bigger breaker.

  6. 6. Damaged cord, plug or socket

    Technician job

    Signs: Scorch marks, loose pins, cord crushed by castors or a door.

    Fix: An electrician should replace the damaged parts.

When to call a technician

Call an electrician or refrigeration technician if the breaker trips more than once after you have moved other loads off the circuit, for any RCCB trip you cannot explain, or if you see scorching or smell burning. Tell them which device trips and when. Keep the unit off and move stock in the meantime.

Never bypass an RCCB, tape a breaker on or replace it with a higher rating; these devices protect people from shock and fire. Isolate at the MCB before touching plugs or wiring that may be damaged. Units with hydrocarbon refrigerant (R290 or R600a) need ignition-safe repair by trained technicians.

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