Why Does My Circuit Breaker Keep Tripping?

A circuit breaker that trips is a warning to investigate, not an inconvenience to keep resetting. Too much load, damaged wiring, faulty equipment or another electrical issue may be responsible. Understanding which device has tripped helps, but it does not establish the cause. Dr Watt investigates circuit faults across the Sunshine Coast and explains what needs attention before recommending repairs.

What a circuit breaker does

A standard circuit breaker protects circuit wiring against excessive current, including overloads and short circuits. When the conditions for operation are reached, it interrupts the supply to the circuit. Correctly selected protection helps reduce the risk of cable damage and overheating. It does not prevent every electrical fire, detect every poor connection or provide the earth leakage protection of a safety switch. A breaker's rating must suit the circuit design and installation conditions, and replacing it with a higher-rated device without assessing the wiring can leave the circuit inadequately protected.

Circuit breaker, safety switch or RCBO?

• Standard circuit breaker: protects circuit wiring against excessive current. It does not provide residual current protection simply because it has an on/off lever.
• Safety switch (also called an RCD): detects an imbalance between current flowing out and returning, which can indicate current leaking to earth. It protects against certain electric shock risks, but it does not make every electrical situation safe.
• RCBO: combines circuit breaker and residual current protection in one device. A trip may involve excessive current or leakage, and the device position alone does not identify the reason.

A TEST or T button usually indicates residual current protection. Do not remove switchboard covers or touch wiring to identify equipment. If you are unsure which device has tripped, call an electrician.

Overload: too much demand on the circuit

An overload can occur when equipment draws more current than the circuit is designed to carry. Several high-power appliances operating together may cause a trip, even when they are connected to different outlets on the same circuit. Adding power points or using a larger power board does not increase circuit capacity, and the solution may involve changing how equipment is used or installing a suitable additional circuit after assessment. Overload protection may operate after a delay, but a delayed trip does not prove overload, because other faults can also appear after equipment has been running for a while. See our power point installation page.

Short circuit: a fault with very high current

A short circuit is an unintended low-impedance connection between conductors at different electrical potentials, such as active and neutral. It can allow a large fault current to flow and cause protective equipment to operate rapidly. Possible causes include damaged insulation, a cable damaged by screws or pests, or a fault inside connected equipment. These are examples, not a diagnosis from the trip alone. Do not use wire colour to decide whether something is safe to touch, because colours differ between wiring systems and periods, and an installation may contain alterations or incorrect identification. Electrical testing is required.

Earth faults and leakage

An earth fault can occur when an active conductor contacts an earthed conductive part, such as a metal equipment enclosure. A sufficiently large fault current may operate a circuit breaker, while smaller leakage currents may need a safety switch to detect and interrupt them. Damaged insulation, moisture or faulty equipment can create leakage paths. A standard circuit breaker should not be relied on to detect the small currents that can injure a person. Do not assume the circuit is safe because a breaker has not tripped. Keep clear of damaged fittings and arrange professional assessment.

What to do when a breaker trips

Stop before troubleshooting if there is smoke, sparking, a burning smell, unusual heat, water damage or damaged switchboard equipment. Keep clear and seek urgent assistance. For fire or immediate danger, move to safety and call 000. For shocks or tingles from taps, appliances or metal fittings, stay clear, warn others, do not touch the switchboard and call Energex immediately on 13 19 62.

If there are no danger signs, the board is dry and undamaged, and you can identify the normal controls, switch off and unplug safely accessible plug-in equipment on the affected circuit. Do not disconnect hardwired equipment, open fittings or enter the roof space to investigate. You may attempt one reset using the device's operating instructions. Some lever-operated devices need to move fully to OFF before ON, and you should not force a mechanism or guess how an unfamiliar device works.

If it will not reset or trips again, leave the affected circuit off and call a licensed electrician. Do not repeatedly reset, bypass or hold the device on, and do not reconnect suspect equipment elsewhere to test it.

Can the last appliance prove what caused the trip?

No. If a trip follows connection or use of an appliance, that equipment may be involved, but the sequence alone does not prove it is faulty. Combined load, wiring or another condition may contribute. Leave suspect equipment unplugged and arrange advice or testing before using it again. Likewise, a breaker that will not reset does not prove the fixed wiring is the cause, because hardwired equipment, overlooked appliances or the protective device may be involved. For guidance specifically about a tripped safety switch, read our safety switch troubleshooting article.

When to arrange fault finding

Arrange an investigation if trips recur, the device will not reset or you are uncertain what has happened. Tell us which switch tripped, what equipment was running, how long it had been running and whether the problem follows rain or recent work. Dr Watt works through the symptoms and test results, explains the findings and discusses repair options. If the board itself is the issue, see our switchboard upgrades.

Fault finding is generally charged for investigation time, and applicable charges are explained before attendance is arranged. Call Lior on 0410 699 352 to discuss the fault and check availability. Urgent and after-hours attendance is subject to availability. Do not wait for a callback where there is immediate danger.

QLD Electrical Contractor Licence 82601 · 30+ years' electrical experience · Based in Mooloolah Valley