Last updated:
Every Johannesburg homeowner knows the ritual. The lights go out, you wait, and some time later they come back on with a flicker and a click. What you may not realise is that the moment the power returns can be the most dangerous part for your appliances. Fridges, TVs, routers, pool pumps and computers are all at risk from surges, and the damage is often blamed on “old age” when the real culprit is dirty power.
What is a power surge?
South African mains supply is nominally 230 V. A surge is a short spike well above that, lasting anywhere from a few microseconds to a few seconds. Electronics are designed with some tolerance, but repeated or large spikes wear down components or destroy them outright.
There are two main types:
- Internal surges come from within your own property, such as a large motor (geyser element, aircon compressor, pool pump) switching on and off.
- External surges come from the grid itself: switching by the utility, faults on the line, and lightning.
Why Johannesburg is a surge hotspot
Load shedding and the return of power
When supply is restored after an outage, voltage can overshoot or fluctuate for a short time while the network re-stabilises. When a whole street comes back on at once, every fridge compressor, geyser and aircon demands current at the same moment. The result can be a sag followed by a spike.
Highveld lightning
Johannesburg gets some of the most intense lightning in the world during the summer storm season. A strike does not have to hit your house. A strike on a nearby line or pole can send a surge along the cables and into your circuits.
Ageing infrastructure and older wiring
Many suburbs have older housing stock with outdated distribution boards, no earth leakage protection, and degraded or loose neutral connections. A loose neutral is especially dangerous, because it can cause some outlets to see far more than 230 V, and it can destroy several appliances at once.
Warning signs of surge damage
- Appliances that fail soon after power returns.
- Lights that flicker, dim or burn out repeatedly.
- Buzzing or a burning smell from outlets or the distribution board.
- Plug sockets that are warm, discoloured or crackling.
- Digital clocks and electronics resetting for no reason.
- Breakers that trip often.
Burning smells or hot sockets are an immediate reason to switch off at the main and call an electrician.
The layers of protection
The best protection is layered, like a defence in depth.
1. Whole-house surge protection at the distribution board
A surge protection device (SPD) installed at the distribution board diverts large surges to earth before they spread through the house. It is the first and most important line of defence, and it protects hard-wired items like geysers, stoves and lighting that plug-in protectors cannot cover. SPDs are rated by type and by how much current they can divert, and they must be matched to the installation. They also wear out after absorbing big hits, so check the status indicator and replace them when they show a fault.
2. A properly installed earth
Surge protection only works if the surge has somewhere to go. If your earth connection is poor or missing, the best SPD in the world cannot do its job. Have an electrician test your earthing, especially in older houses.
3. Point-of-use protection for sensitive equipment
For TVs, computers, home offices and entertainment systems, add a quality surge-protected plug strip or a small UPS. Choose products from reputable brands with a clear joule rating and a protection indicator light. Very cheap extension leads often have no protection at all, even when they say they do.
4. A UPS for the things that matter
A UPS (uninterruptible power supply) gives a short bridge of battery power and filters the incoming supply. It is ideal for routers, PCs, servers and security systems. Many South Africans now use inverter systems, but not all inverters clean the power or switch over safely. Ask your installer how the changeover is handled, because a slow or poorly built changeover can cause its own surges.
5. Unplug during storms and on return of power
It is the oldest advice and it still works. Unplug valuable equipment during electrical storms. After a long outage, consider leaving key appliances unplugged or switched off for a minute or two once the power returns, so you can see that the supply has settled.
Fridges and freezers
Fridge and freezer compressors are vulnerable when power cuts and returns quickly, because the compressor tries to restart against pressure still in the system. Many fridges have a built-in delay, but older ones do not. A fridge guard (a plug-in device that delays restart and cuts out on over- and under-voltage) is a cheap way to protect an expensive item, and worth using on freezers full of food.
Safety first: what not to do
- Do not overload a single socket with multiple adaptors.
- Do not use damaged cords or “daisy-chain” extension leads.
- Do not bypass or tape over a tripping breaker.
- Do not open the distribution board yourself.
- Do not connect generators or inverters to the house wiring without a proper changeover switch installed by a qualified electrician. Back-feeding the grid is illegal and can kill a person working on the line.
Your distribution board matters
An up-to-date board with earth leakage protection, correctly sized breakers and a surge device is the foundation of a safe home. If your board still has old rewireable fuses, no earth leakage unit, or signs of heat damage, it is time for an upgrade. A Certificate of Compliance (CoC) is also a legal requirement when selling a property, so it pays to have the installation checked well before you list.
Frequently asked questions
Will insurance cover surge damage?
Many household policies cover damage from power surges and lightning, but conditions and excesses vary. Keep your receipts, take photos, and ask your electrician for a written report on the cause of the damage to support your claim.
Do I need surge protection if I already have an inverter?
Often yes. An inverter does not necessarily protect against grid surges or lightning, and the changeover itself can be a source of spikes.
How long does a whole-house SPD last?
It depends on how many surges it absorbs. Check the indicator regularly and have it tested during any routine electrical inspection.
Let us help
Supa Nova Electrical Power & Plumbing has been serving Johannesburg since 1981. We can inspect your distribution board, test your earthing, and fit surge protection suited to your home. We cover a 20 km radius of Maryvale, offer free quotations, and charge no call-out fee: just labour plus a R400 travelling fee. We work Monday to Friday, 7:00 to 17:00 (Saturdays by prior arrangement).
If a surge has already tripped your board or damaged an appliance, our emergency electrician service can help. Once protection is fitted we can also issue an electrical certificate of compliance, and you can see all of our electrical services here. Related reading: why your earth leakage keeps tripping.
Call us on 011 485 1324 to protect your home before the next storm.