Why You Need a Generator in Pretoria
Last winter I got called to a house in Centurion where the owner had bought a 3kVA petrol generator off Marketplace and plugged his entire DB board into it using a male-to-male cable he made himself. The generator was screaming at full load, the voltage was sagging to 180V, and his fridge compressor was clicking on and off every few seconds. That call-out cost him more than a proper installation would have from the start.
Pretoria homes face a unique combination of power challenges. Load shedding is the obvious one, but we also deal with municipal infrastructure failures, transformers blowing in Hatfield, cable theft in Brooklyn, ageing substations in Arcadia that cause unplanned outages lasting two or three days.
Then there is the Highveld thunderstorm season from October to March. I have seen a single lightning strike in Garsfontein take out an entire street's supply for 36 hours because the municipal fuses blew and there was no crew available to replace them.
A generator is not optional anymore, it is basic infrastructure. The question is not whether you need one. It is which size to get, what type of changeover switch to fit, and how to install it so it does not kill someone or burn your DB board out.
Types of Generators for Home Use
I had a customer in Waterkloof Ridge who bought a petrol inverter generator to run his borehole pump, geyser, and pool pump. It lasted three weeks before the alternator burned out from sustained overload. Wrong tool for the job. Here is what each type is actually suited for:
Petrol Generators (2kVA - 8kVA)
The most common entry-level option. Affordable to buy but relatively expensive to run. Best suited for powering essentials, lights, TV, Wi-Fi router, phone charging, during short outages. Not ideal for running geysers, stoves, or air conditioning. Typical cost: R5,000 to R25,000 for the unit alone.
Diesel Generators (5kVA - 20kVA+)
The workhorse of backup power. More fuel-efficient than petrol, significantly longer lifespan, and capable of running heavier loads. This is what I recommend for most Pretoria homes that want to power more than just the basics. A 10kVA diesel unit can comfortably run lights, plugs, a geyser, and most essential circuits. Typical cost: R25,000 to R80,000+ for the unit.
Inverter Generators
Quieter than conventional generators and produce cleaner power, which is better for sensitive electronics. Popular in estates like Midstream and Irene Farm Villages where noise restrictions apply. More expensive per kVA than standard generators. Typical cost: R15,000 to R60,000.
Three-Phase Generators
Required for homes or businesses with three-phase power supply. Less common in residential properties but essential for some larger homes in suburbs like Waterkloof and Bryanston, or for commercial premises. Significantly more expensive and complex to install.
How to Size Your Generator
This is where most people burn money. A customer in Moreleta Park bought a 5kVA generator because the salesman at the hardware store said it would "run the whole house." It could not even start his pool pump, the motor draws nearly 2,250W on startup, and the generator's peak capacity was already eaten up by the fridge and geyser. He had to buy a second, larger unit. The first one sits in his garage collecting dust.
On the other end, I see people buying 20kVA diesel units for a three-bedroom townhouse. The generator runs at 15% load, which causes wet-stacking, unburnt fuel builds up in the exhaust, carbon deposits coat the cylinders, and the engine life drops dramatically.
The key is understanding your essential load, the circuits you actually need to keep running during a power outage, not your entire home's total capacity. Here is a rough guide:
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Lights (10 LED bulbs) | 100W | 100W |
| TV + decoder | 200W | 200W |
| Wi-Fi router | 20W | 20W |
| Fridge/Freezer | 150W | 600W |
| Microwave | 1,000W | 1,500W |
| Electric geyser (150L) | 2,000W | 2,000W |
| Pool pump | 750W | 2,250W |
| Air conditioner (small) | 1,200W | 3,600W |
| Electric gate motor | 300W | 900W |
Sizing rule of thumb
- Small home (lights, plugs, fridge): 3-5kVA generator
- Average 3-bedroom home (lights, plugs, fridge, geyser): 7-10kVA generator
- Large home (most circuits including pool pump): 10-15kVA generator
- Always factor in starting watts, motors draw 2-3x their running wattage on startup
- A professional load assessment before purchase saves you from expensive mistakes
Generator Installation Costs in Pretoria (2026)
The cost of a generator installation has two main components: the generator unit itself, and the installation work (changeover switch, wiring, weatherproof housing, and connection to your DB board). Here is what you should budget for in 2026:
| Installation Type | Cost Range (excl. VAT) |
|---|---|
| Manual changeover switch + wiring (basic) | R4,500 - R7,000 |
| Automatic changeover switch + wiring | R8,000 - R15,000 |
| Full installation (generator + auto changeover) | R30,000 - R80,000+ |
| Generator weatherproof enclosure/housing | R3,000 - R8,000 |
| Fuel line and tank installation | R2,000 - R5,000 |
| DB board modification for generator circuits | R2,000 - R4,000 |
| Three-phase changeover installation | R15,000 - R25,000 |
Prices are estimates based on typical Pretoria market rates as of March 2026 and exclude VAT (15%). Generator unit costs are additional and vary by brand, size, and supplier.
The running costs nobody mentions
Everyone budgets for the generator and changeover switch. Nobody budgets for fuel, oil changes, filters, and annual servicing. A 10kVA diesel running 4 hours a day during Stage 4 burns through R80-R150 in diesel per day, that is R2,400-R4,500 a month. Oil changes every 100-200 hours add another R500-R800 each time. Factor this in before you decide on a generator size.
Changeover Switches, The Most Important Part
The changeover switch is the single most critical component of your generator installation. More important than the generator itself. Get this wrong and someone dies, that is not an exaggeration.
Here is what happens when someone connects a generator to their DB board without a changeover switch: the generator backfeeds 230V through the meter, up into the municipal transformer, and steps it up to 11kV on the high-voltage side. A Tshwane linesman working on that line, thinking it is dead because the substation breaker is open, touches the conductor and gets killed. This has happened in South Africa. It is manslaughter, and you are liable.
I have ripped out at least a dozen of these illegal connections across Pretoria. One in Faerie Glen had a male-to-male plug lead, what electricians call a "suicide cord", running from the generator straight into a wall socket. The live pins were exposed on one end while the generator was running. The homeowner's kid could have grabbed it.
Manual Changeover Switch
A proper manual changeover uses a double-throw switch, typically a 63A or 100A unit mounted next to your DB board. You physically flip it from the ESKOM position to the GENERATOR position. The switch mechanically locks out one source before connecting the other, so both can never feed the board at the same time. Cheaper to install (R4,500-R7,000) and dead reliable. Downside: you need to be home to switch over.
Automatic Transfer Switch (ATS)
Detects when Eskom power fails and automatically starts the generator and transfers the load. When Eskom returns, it transfers back and shuts down the generator. More expensive (R8,000-R15,000 installed) but completely hands-off, your power simply stays on.
Essential Circuits Only
Most residential installations feed only essential circuits from the generator, lights, plugs, fridge, gate, alarm. This reduces the generator size needed and keeps installation costs down. Your geyser, pool pump, and stove stay on Eskom-only circuits.
Full Backup
The entire house runs from the generator during an outage. Requires a larger generator (10kVA+) and more expensive changeover equipment. Common in larger homes in Waterkloof, Bryanston, and upmarket estates where running the full household is non-negotiable.
The Installation Process, What to Expect
A proper generator installation takes a full day, sometimes two if we are running conduit over distance or modifying the DB board. Here is what the process looks like step by step:
Site Assessment & Load Calculation
We come out, open the DB board, and clamp-meter the main breaker and individual circuits to measure actual draw. We check the incoming supply, single-phase or three-phase, 60A or 80A main breaker, and work out which circuits are essential and which can stay off during an outage. This is where we catch problems early, like a DB board with no space for a changeover switch, or earth leakage trips that need sorting before anything else happens.
Generator Placement
The generator needs a level, well-ventilated location at least 1.5 metres from windows and doors. In estates like Midstream or Irene Farm Villages, we also ensure compliance with any HOA guidelines for generator placement and housing.
Changeover Switch Installation
The changeover switch mounts next to or inside the DB board. We run the Eskom feed through one side, the generator feed through the other, and the output to your essential circuits. The switch is mechanically interlocked so you cannot accidentally connect both sources at once. Wiring is 6mm or 10mm depending on the load, run in conduit, with proper gland entries and earth bonding throughout. Everything to SANS 10142.
Generator Connection & Testing
The generator is connected to the changeover switch, fuel lines are fitted, battery is connected (for auto-start units), and we test every circuit under load. We simulate a power failure to verify the changeover works correctly in both directions.
Handover & Training
We walk you through the operation, starting procedure, changeover operation, fuel management, and basic maintenance. You get full documentation including a compliance certificate for the electrical work.
Generator Maintenance, Keep It Running
I get emergency calls every time load shedding ramps up from people whose generators will not start. Nine times out of ten the fuel has gone stale, the battery is flat, or the oil has turned to sludge. A generator that has not run in six months is not backup power, it is a problem waiting for the worst possible moment.
Run It Monthly
Even if there is no load shedding, run your generator under load for 15-20 minutes every month. This keeps the engine lubricated, the battery charged, and the fuel circulating. A generator that sits idle develops stale fuel, corroded contacts, and seized components.
Oil & Filter Changes
Change the oil every 100-200 running hours (or annually, whichever comes first). Replace oil and air filters at the same intervals. This is the single most important maintenance task for diesel generators.
Fuel Management
Diesel degrades over time, if you are not using the generator regularly, add a fuel stabiliser. Keep the tank at least half full to reduce condensation. Never store petrol in the generator tank for more than 3 months without stabiliser.
Annual Service
A professional annual service includes oil and filter changes, spark plug or injector check, battery test, coolant level check (water-cooled units), and a full load test. Budget R1,500 to R3,000 per annual service depending on the generator type.
What It Comes Down To
Get the sizing right. Fit a proper changeover switch, manual or automatic, either is fine as long as it mechanically isolates Eskom from the generator. Have a registered electrician do the installation and issue a compliance certificate for the work.
Budget R30,000 to R80,000 for a complete residential installation, generator unit, changeover switch, wiring, and housing. A basic essential-circuits setup with a 5kVA petrol generator sits at the lower end. A full-house backup on a 15kVA diesel with automatic transfer switch is at the top.
At INC Unlimited, we do the load assessment, recommend a generator size, install the changeover switch, connect and test everything under load, and hand you a COC for the electrical work. If you want it done right the first time, get in touch for a free assessment and quote.
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.