DB box keeps tripping: 6 common causes and how to diagnose each (SA electrical guide)
Your distribution board trips every time you switch on the kettle, or randomly in the night. Here's how a registered SA electrician diagnoses the cause without burning hours of your callout fee.
First — which breaker is tripping?
The diagnosis is completely different depending on whether it's the earth leakage unit (ELU) or a circuit breaker. Look at the DB:
- The ELU is usually labelled "ELU" or "Earth Leakage" with a Test button. It protects against electric shock — current going to earth.
- Circuit breakers are labelled per circuit (lights, plugs, geyser, stove). They protect against overcurrent.
If everything goes off when one trips, it's the ELU. If only one room or one type of circuit dies, it's that breaker.
1. ELU trips when you use a specific appliance
Most likely cause: moisture in the appliance. The classic offender is a corroded geyser element — water has penetrated the heating element and current is leaking to earth. Switch off the geyser, leave it 4 hours to dry, switch back on. If it trips again immediately, the element needs replacement.
Other common offenders: kettles with cracked elements, washing machines with internal leaks, garden sockets after rain.
2. ELU trips randomly with no obvious cause
This usually points to a damaged appliance cable or a worn ELU itself. If your ELU is more than 15 years old and trips for no reason, it's at end-of-life. Replacement: about R450-R900 + labour.
3. Circuit breaker trips when kettle + microwave + heater on at once
This is the classic "ring overload": too many high-current appliances on the same plug-point ring. The breaker is doing its job. Solutions: (a) don't run both kettle and microwave at the same time, (b) get an electrician to add a dedicated circuit for the kettle.
4. Circuit breaker trips immediately when you flip it back on
Short circuit somewhere on that line — bare wire touching neutral or earth. Common cause: a damaged extension cord or a recently-installed light fitting wired wrong. Unplug everything on that circuit, then flip the breaker. If it holds, plug things in one at a time to find the offender.
5. Circuit breaker buzzes / hums when carrying current
Loose busbar connection. Heat builds up at the loose terminal, which causes the current to fluctuate, which makes the breaker hum. This is a fire risk. Switch off the main and call a registered electrician. Common after geyser installations or DB upgrades where someone forgot to torque the connections properly.
6. Burning smell from the DB
Switch off the main switch immediately. Don't open the DB cover — there's nothing safe to do at that point. Call an electrician urgently. This is usually arcing on a busbar or a melting breaker. Letting it continue can start a fire.
What you should NOT try yourself in SA
South African electrical regs (SANS 10142) make fixed-wiring work the legal preserve of registered electricians. You can replace a plug, swap a light bulb, repair an appliance cord — that's it. Anything inside the DB or in the wall is illegal for an unregistered person to touch, and your insurance will refuse to cover damage caused by unqualified work.
What a CoC actually proves
A Certificate of Compliance says a registered electrical contractor has tested your installation and certified it complies with SANS 10142-1 on the date of issue. Valid for 2 years if no further work is done. Required when you sell a property. Required for most insurance claims involving electrical fires.
Get this kind of triage in seconds
Sparky, our AI electrical assistant walks SA homeowners through DB-trip diagnosis in plain English, 24/7. If you run an electrical contracting business, set up your own branded version — your customers stop calling you at midnight asking "should I be scared?".
Want this kind of help on your own website?
BOTSIZA gives you a 24/7 AI assistant trained for your trade. From R299/month.
Set up your bot →