The Short Answer
An earth leakage trips when it detects electricity escaping to earth instead of returning along the neutral, normally 30 milliamps or more. If it keeps tripping, something in your house is leaking current. The usual suspects are a failing geyser element, water in an outdoor socket or light, a faulty appliance, damaged wiring, a badly wired inverter, or an old earth leakage unit that has become oversensitive.
The unit itself is almost never the real problem. It is doing its job. The fix is to find the circuit or appliance that is leaking, switch it off, and have it repaired.
Quick diagnosis
- Trips when it rains: water in an outdoor fitting, pool pump, gate motor or ceiling light
- Trips at the same time each night: something on a timer, most often the geyser
- Trips when you use one appliance: the appliance is faulty, not the wiring
- Trips when grid power returns or the inverter switches over: an inverter earthing fault
- Trips instantly with every breaker off: call an electrician, do not keep resetting
What Your Earth Leakage Is Actually Doing
The earth leakage unit, sometimes called an earth leakage relay, an RCD or simply "the big switch with the test button", watches the current going out on the live wire and coming back on the neutral. In a healthy circuit those two are equal. When they are not, the difference has gone somewhere else: into the earth wire, into wet brickwork, or through a person.
Residential units in South Africa are rated to trip at 30 mA, and SANS 10142-1 requires that protection on socket-outlet circuits. At 30 mA a shock is unpleasant but survivable. A few hundred milliamps through the chest for long enough is not. The unit is designed to cut the supply in a fraction of a second, which is why it is the single most important safety device on your DB board.
It is different from a circuit breaker. A breaker trips when a circuit draws too much current, for example when the kettle, heater and microwave all run on the same plug circuit. An earth leakage trips on leakage, which can be tiny in terms of load. That is why an earth leakage can trip while nothing much is switched on, and why it can be harder to diagnose.
How to Find the Faulty Circuit Safely
You can narrow the problem down yourself without opening anything. All of this is done with switches on the front of the DB board. If the board is wet, smells burnt, or you feel even a tingle touching it, skip straight to calling an electrician.
Unplug everything you can
Kettle, washing machine, fridge, TV, chargers, the lot. This takes appliances out of the picture so you are testing the wiring first.
Switch off every circuit breaker
Leave the main switch on, but flip every individual breaker down. On most Pretoria boards that is somewhere between eight and twenty switches.
Reset the earth leakage
Push it back up. If it trips straight away with every breaker off, stop here. The fault is in the board, the incoming supply, a neutral-to-earth short, or the unit itself, and that is a job for an electrician.
Switch breakers on one at a time
Wait about a minute between each. When the earth leakage trips, the breaker you just switched on is your suspect. Switch that one off, reset, and carry on with the rest to make sure there is only one.
Plug appliances back in one at a time
With the good circuits restored, reconnect your appliances one by one. If the trip follows a specific appliance, it is the appliance. Old kettles, washing machines, dishwashers and bar heaters are the repeat offenders.
Leave the suspect off and call us
Note which circuit it is. We will test the insulation on that circuit with a proper meter, which tells us whether the problem is in the cable, a fitting or something connected to it.
Why this doesn't always work
Most household breakers in South Africa only switch the live wire. The neutral stays connected even when the breaker is off. So if the fault is a neutral touching earth somewhere, say a nail through a cable or a waterlogged light fitting, switching that circuit's breaker off may not stop the trip. You end up chasing the fault from circuit to circuit. That pattern is a strong clue in itself, and it is exactly what an insulation test is for.
Why It Trips When It Rains
Gauteng's storm season runs roughly from October to March, and the afternoon downpours find every weak seal on your property. Water conducts. When it reaches a live part, a little current leaks to earth and the unit trips. When things dry out the next morning, the leak disappears and everything resets fine, which is why rain-related faults feel random.
These are the places we find water most often in Pretoria homes:
Outdoor sockets
Weatherproof covers that crack in the sun, or were never weatherproof to begin with. Patio and braai-area plugs are the classic.
Garden and wall lights
Perished rubber seals, spike lights sitting in irrigated beds, and cable joints buried in soil with insulation tape around them.
Pool pump and gate motor
Connections in pump rooms that flood, and gate motor cabling running through damp trenches. Both live outside and get no attention until they fail.
Electric fence energiser
Usually on its own plug, often in a garage or outside box. Water in the energiser or its supply plug will trip the whole circuit.
Ceiling lights under a leaking roof
Water runs along the trusses and drips into a downlighter. If trips started after a hailstorm, check your ceiling for damp patches.
The geyser area
A leaking geyser or blocked drip tray can soak the isolator and thermostat cover. Combine that with a corroded element and it trips every storm.
A useful test: next time it rains, switch the outdoor lighting and outdoor plug circuits off before the storm arrives. If the earth leakage stays up all afternoon, you have found your area. Leave them off until an electrician has looked, because a fitting that leaks to earth in the rain is a shock risk to anyone touching it.
Common Causes, the Clues, and the Fix
When we arrive on a tripping call-out, the pattern of the trips usually tells us where to look before we have unpacked the meter.
| Cause | Typical clue | Usual fix |
|---|---|---|
| Failing geyser element | Trips when the geyser timer comes on, or a while after | Replace element, check thermostat and wiring |
| Water in an outdoor fitting | Trips in rain or after the sprinklers run | Replace or reseal the fitting, correct the cable joint |
| Faulty appliance | Trips when one specific appliance is used | Repair or replace the appliance |
| Damaged cable | Trips after renovations, picture-hanging or rodent activity | Locate and repair the damaged section |
| Neutral-to-earth fault | Trips even with the suspect breaker off | Insulation testing to trace the fault |
| Inverter earthing fault | Trips when grid power returns or during changeover | Correct the neutral-earth bonding arrangement |
| Too much on one unit | Random trips, worse with lots of electronics on | Split circuits across two earth leakage units |
| Worn earth leakage unit | Trips with nothing on, or the test button feels stiff | Test trip current and time, replace the unit |
The geyser deserves special mention. Pretoria's hard water scales elements up, the scale traps heat, and eventually the element sheath cracks. Water then reaches the heating coil and current leaks to earth, but only while the element is energised. Our geyser guide covers the other warning signs.
The "too much on one unit" cause is more common than people expect. Every computer, TV, LED driver and phone charger leaks a tiny amount of current to earth by design. Individually it is nothing. Put a home office, two TVs, a fish tank and fifty LED downlighters on one 30 mA unit and the background leakage can sit uncomfortably close to the trip point, so the next small leak pushes it over. Good practice is to keep standing leakage well below the trip rating, which on bigger homes means splitting the board across more than one earth leakage unit.
Tripping at Night, or Seemingly at Random
Night-time trips almost always have a timer behind them. Think about what switches itself on while you sleep:
- The geyser, if it is on a timer or a smart controller that heats overnight
- The pool pump, which is often set to run in the early hours
- The fridge or freezer defrost heater, which cycles every few hours
- Outside lights on a photocell or timer, collecting dew in the early morning
Write down when the trip happened, as best you can tell from your clocks or alarm system log, and compare it to those timers. That one piece of information often saves an hour of fault finding.
Truly random trips, with no link to weather, time or appliance, point towards either the cumulative leakage problem above, an intermittent fault such as a loose connection that arcs to earth, or a tired earth leakage unit. Units do wear. When we test one during an inspection we measure the actual current and time it takes to trip, and an old unit that trips well below 30 mA is a nuisance, while one that trips too slowly or not at all is dangerous.
Tripping When the Power Comes Back or the Inverter Switches Over
This one became common during the load shedding years and we still see it weekly. The earth leakage trips the moment grid power returns, or the moment the inverter changes from grid to battery. Everything else works perfectly.
The cause is almost always the neutral-to-earth bond. On grid power, your neutral is bonded to earth at the supply. When a hybrid inverter islands your house during an outage, it has to create its own neutral-earth bond so that your earth leakage has a reference and can still trip on a real fault. When the grid comes back, that bond has to be released. If the inverter, an external changeover contactor, or the way the essential and non-essential boards are wired gets this wrong, the earth leakage sees an imbalance at the switchover and trips.
The more serious version
Nuisance tripping at changeover is annoying. The opposite fault is worse: an installation where the earth leakage never trips on battery power because there is no neutral-earth reference at all. The house runs fine, so nobody notices, but during an outage you have no shock protection. We test for this on every inverter installation by simulating a grid failure and checking that the earth leakage still operates.
Both versions need an electrician to correct, and both will be flagged on a COC inspection. If you have solar or a hybrid inverter, our solar and inverter COC guide explains what else gets checked.
Why You Should Never Bypass It
We regularly open DB boards where someone has moved a wire to feed circuits around the earth leakage, or bridged it out entirely, because it "kept tripping for no reason". It wasn't tripping for no reason. And the fault it was reacting to is still there, now with nothing watching it.
If you need power urgently, the right move is to leave the faulty circuit's breaker off and run the rest of the house normally. Most of the time you lose the outside lights or one plug circuit for a day, not the whole house.
What Fixing It Costs in Pretoria (2026)
Most tripping faults are found and fixed in a single visit. These are our 2026 prices; anything not listed is quoted once we know what we are dealing with, and we never start work without your go-ahead.
| Item | 2026 price | Notes |
|---|---|---|
| Fault-finding visit | R650 | Standard home: testing, diagnosis and a clear explanation |
| Larger or complex installations | R500 to R1,200 | Assessment fee scales with size and complexity |
| Earth leakage relay replacement | R800 to R1,500 | Where the unit no longer trips within 30 mA / 300 ms |
| Geyser element replacement | R1,200 to R2,000 | Including testing of thermostat and supply |
| Circuit breaker replacement | R250 to R600 | Faulty or incorrectly rated breakers |
| Outdoor fittings, cable repairs, inverter corrections | Quoted on site | Depends on access and what we find |
Full details are on our electrical fault finding page and our pricing page.
When to Stop Resetting and Call an Electrician
Resetting once to see what happens is fine. Resetting ten times a day is not a fix. Call us, or any registered electrician, straight away if:
It trips with every breaker off
The fault is in the board, the supply or the unit, not in a circuit you can isolate.
You smell burning
Switch off the main switch. Heat damage behind a wall is a fire risk, not an inconvenience.
Anyone felt a tingle or shock
From a tap, a geyser pipe, a metal door frame or an appliance. Leave the area off and call immediately.
The DB board is wet or warm
Do not touch it with wet hands or while standing on a wet floor.
For the first three, treat it as urgent. Our emergency electrician guide explains what to do while you wait.
Questions We Get Asked
Straight answers, from a Pretoria electrician who chases these faults every week.
How often should I press the test button?
Once a month. It proves the mechanism works. It does not prove the unit trips at the right current or fast enough, which is what we measure during an inspection.
Will a tripping earth leakage fail my COC?
The tripping itself doesn't, but the fault causing it usually will. A missing, bypassed or slow earth leakage is an automatic fail.
Can a storm or surge damage the earth leakage?
Yes. A nearby lightning strike can damage the unit or leave it oversensitive. Our surge protection guide covers how to protect the board.
My kettle trips it. Is that the wiring?
Almost certainly the kettle. Old kettles with scaled or cracked elements leak to earth when hot. Try a different kettle on the same plug before calling anyone.
Is it safe to leave one circuit off for a few days?
Yes, as long as nothing critical such as medical equipment is on that circuit. It is far safer than bypassing protection.
Should I just replace the earth leakage myself?
No. Work inside the DB board must be done by a registered person, and a new unit will trip just like the old one if the fault is still there.
It's Telling You Something. Listen to It.
A tripping earth leakage is the cheapest warning your electrical installation will ever give you. Most of the time the fault behind it is a R1,500 repair: a geyser element, a perished outdoor light, a worn unit. Ignored or bypassed, the same fault can become a shock or a fire.
Isolate the circuit, leave it off, and get it tested. We do fault finding across Pretoria, Centurion, Midrand and the surrounding areas, Monday to Saturday.
Call 072 681 4615 or request a callback online. Tell us when it trips and which breaker you have left off, and we can usually narrow it down before we arrive.
Written by Andre
Registered Electrician & Founder of INC Unlimited Pty. Ltd
With over 30 years of experience in the electrical trade across Pretoria and Gauteng, Andre and the INC Unlimited team have completed over 500 COC inspections, installations, and electrical projects. SANS 10142 compliant. Based in Equestria, Pretoria.