Why your power keeps tripping (and what's actually happening)

It's 9:30 PM on a Wednesday. You're halfway through loading the dishwasher when every light in the kitchen goes out. The fridge hums to a stop. You walk to the switchboard in the hallway, flip the switch back up, and ten minutes later it trips again. This is the third time this week.

By the end of this article, you'll know which switch is tripping, what's causing it, and when you actually need to call someone.

Which switch tripped — circuit breaker or RCD?

Your switchboard has two types of switch. They look similar but do different jobs.

Circuit breakers are the smaller switches, usually black or grey, labelled with room names or numbers (Kitchen, Bedroom 2, Lights). They protect individual circuits from overload — too many appliances drawing power at once. When one trips, only that circuit loses power. The rest of the house stays on.

RCDs (residual current devices, also called safety switches) are the larger switches, usually white or cream, with a test button. They monitor current leakage and cut power in 0.03 seconds if they detect it. When an RCD trips, multiple circuits go dark — often half the house or more. RCDs are mandatory in NSW for power points, lighting, and any circuit installed or modified after 2000.

Look at your switchboard. If one small switch is down and the rest are up, it's a circuit breaker. If a large switch with a test button is down, it's the RCD.

Why circuit breakers trip

Circuit breakers trip for one reason: too much current on that circuit. Each breaker is rated for a maximum load — typically 10 amps for lighting, 20 amps for power points. When the total draw exceeds that, the breaker cuts power to prevent the wiring from overheating.

Common causes in Sydney homes:

• Multiple high-draw appliances on one circuit. Kettle, toaster, and microwave all running at once in the kitchen. Space heater and hairdryer on the same bedroom circuit. The breaker isn't faulty — you've just hit the limit.
• A faulty appliance drawing more current than it should. Washing machine with a worn motor. Fridge with a failing compressor. Unplug appliances one by one and reset the breaker. If it stays on, the last thing you unplugged is the problem.
• Old wiring with degraded insulation. More common in pre-1980s homes. The insulation breaks down, resistance increases, and the circuit heats up faster under normal load. This requires a sparkie — you're not fixing it yourself.

If the same breaker trips every time you use a specific appliance, that appliance is the problem. If it trips randomly with no pattern, the wiring or the breaker itself is suspect.

Why RCDs trip

RCDs trip when they detect current leakage — electricity escaping the circuit and flowing somewhere it shouldn't. This happens when:

• Water gets into electrical equipment. Outdoor power points, garden lights, pool pumps. Did one in Marrickville last November — post-war brick, where the previous owner had run garden spike lights off an extension lead buried under mulch. Every time it rained, the RCD tripped. Took us 20 minutes to find the corroded splice.
• An appliance has a fault to earth. Worn insulation inside a kettle, dishwasher, or washing machine. The RCD detects current leaking through the earth wire and cuts power. Unplug appliances one by one, same process as a circuit breaker.
• The RCD itself is worn. RCDs have mechanical parts that degrade over 10 to 15 years. If yours trips with no load on the circuit — nothing plugged in, nothing running — the RCD is probably at end of life. Replacing it costs $180 to $280 plus GST.

If your RCD only trips when it rains, start with outdoor circuits. If it trips randomly regardless of weather, start unplugging appliances.

The decision tree — what to do right now

If a circuit breaker trips once and stays on after reset: probably fine. Could be a momentary surge from the grid or an appliance startup spike. Monitor it. If it trips again within 48 hours, investigate.

If a circuit breaker trips twice in one day: you have an overload or a faulty appliance. Unplug everything on that circuit. Reset the breaker. Plug appliances back in one at a time, waiting 10 minutes between each. When it trips, you've found the culprit.

If an RCD trips once and stays on: same as above. One-off trips happen. If it trips again within a week, you have a fault.

If an RCD trips repeatedly — three times in a week, twice in a day: do not keep resetting it. You have current leakage somewhere. This is a shock hazard. Call a licensed electrician. In NSW, you can verify licences at NSW Fair Trading.

If you reset the switch and it trips immediately — won't stay up at all: major fault. Do not force it. Call a sparkie today.

What actually fails in Sydney homes

In the homes we work in, the version of this that actually fails is outdoor wiring. Eastern Suburbs, Inner West, North Shore — doesn't matter. Outdoor power points crack. Junction boxes corrode. Pool equipment gets wet. Garden lights installed by the previous owner 15 years ago have been buried under soil and roots.

The second most common cause is old appliances. Dishwashers and washing machines over 10 years old develop earth faults as seals wear and water seeps into wiring. The RCD is doing its job — it's protecting you from a shock.

The least common cause, but the one people assume first, is the RCD itself being faulty. It happens, but not as often as people think. If your RCD is tripping, it's usually detecting a real fault.

When you have a real problem vs a quirk

Real problem:

• Trips repeatedly (more than twice in a week).
• Trips immediately on reset.
• Trips only when you use a specific appliance.
• Trips only when it rains.
• Trips and you smell burning plastic or see scorch marks on a power point.

Quirk:

• Trips once every few months with no pattern.
• Trips during a thunderstorm (voltage spike from the grid).
• Trips when you turn on a high-draw appliance and the circuit was already near capacity (not a fault, just poor circuit design).

If it's a quirk, you can live with it. If it's a real problem, you're either calling someone or unplugging the faulty appliance permanently.

What a sparkie will actually do

A licensed electrician will:

1. Test the RCD with a proper tester (not just the test button — that only checks the mechanical trip, not the sensitivity).
2. Measure insulation resistance on each circuit to find leakage.
3. Inspect the switchboard for loose connections, corrosion, or worn breakers.
4. Check outdoor circuits first if the fault is weather-related.
5. Replace the faulty component — RCD, breaker, or appliance wiring.

If they quote you without doing steps 1 and 2, they're guessing. Walk away.

This article is general guidance only. Any electrical work in NSW must be performed by a licensed tradesperson — see NSW Fair Trading for licence verification.

Frequently asked questions

What's the difference between a circuit breaker and an RCD in Australia?

A circuit breaker protects your wiring from overload — too many appliances on one circuit. An RCD (residual current device, also called a safety switch) detects current leakage and cuts power in milliseconds to prevent electrocution. Both live in your switchboard. RCDs are mandatory in NSW for power points and lighting circuits.

Why does my RCD trip when it rains in Sydney?

Water ingress into outdoor power points, garden lights, or pool equipment causes current leakage. The RCD detects it and trips. Common culprits: cracked outdoor sockets, corroded junction boxes, or poorly sealed garden spike lights. If it only trips during or after rain, start with outdoor circuits.

Can I just reset the switch and ignore it?

If it trips once and stays on after reset, probably fine — could be a momentary surge. If it trips repeatedly (twice in a day, three times in a week), you have a fault. Ignoring it means either living without power on that circuit or risking a fire or shock hazard. Get it checked.

How much does it cost to fix a tripping circuit breaker in Sydney?

Depends entirely on the cause. If it's a faulty appliance you can unplug yourself, $0. If it's a worn RCD that needs replacing, $180 to $280 plus GST for the part and labour. If it's a wiring fault behind walls, could be $400 to $800. No sparkie quotes this consistently — you'll get three answers from three electricians.

If you'd rather not be the one standing in the hallway at 9:30 PM resetting switches and googling "RCD keeps tripping" — that's literally why we exist. Wenest members get this handled without the calls. See how it works.