Can a Diesel Generator Run a Whole House? A Homeowner’s Guide
With South Africa’s power challenges continuing to impact daily life, many homeowners are turning to diesel generators for uninterrupted electricity. But can a diesel generator run your entire home — including major appliances, electronics, and lighting? This guide breaks down everything you need to know to answer that question.
🔍 Quick Answer:
Yes, a diesel generator can run a whole house — provided it is correctly sized to your home’s power requirements. For most medium to large households in South Africa, a 7.5kVA to 20kVA diesel generator is typically sufficient to power essential appliances, lights, and electronics during load shedding or extended outages.
1. How Much Power Does a House Use?
The average South African household consumes between 3kW and 6kW during load shedding (excluding energy-intensive appliances like geysers, ovens, and air conditioners). Here’s a typical breakdown:
| Appliance | Power Consumption |
|---|---|
| Fridge/Freezer | 150–300W |
| Lights (LEDs) | 100–300W |
| Wi-Fi Router & TV | 50–200W |
| Microwave | 800–1500W |
| Geyser | 3,000W |
| Washing Machine | 1,000–2,000W |
| Air Conditioner | 1,500–3,000W |
📌 Total load when conservative: 3–5kW
📌 Total load with all appliances on: 8–10kW or more
2. Generator Size Needed to Power a Whole House
To run an entire house, including geysers and ACs, you’ll need a diesel generator in the 7.5kVA to 20kVA range. Here’s a guide:
| Home Type | Recommended Generator Size |
|---|---|
| Small home / essential loads only | 5.5kVA – 7.5kVA |
| Medium house with major appliances | 8kVA – 12kVA |
| Large house / full backup including geyser and AC | 15kVA – 20kVA+ |
✅ Diesel generators offer better fuel economy, longer lifespan, and are ideal for high-demand, long-duration use.
3. Benefits of Using a Diesel Generator
| Benefit | Description |
|---|---|
| ⛽ Fuel Efficiency | Diesel engines burn less fuel under load compared to petrol. |
| 💪 Durability | Designed for continuous use and heavy-duty applications. |
| 🔋 High Output | Easily powers large homes and high-wattage appliances. |
| 🔧 Lower Maintenance | Longer intervals between servicing compared to petrol units. |
4. Single vs Three-Phase Power Considerations
-
Most residential homes use single-phase power.
-
Large homes or properties with pumps, pool systems, or 3-phase air conditioning may require a three-phase diesel generator.
🛠 Always check your DB board or consult an electrician to verify your power supply setup before purchasing.
5. Can You Connect a Diesel Generator to Your DB Board?
Yes — through a manual changeover switch or automatic transfer switch (ATS). This allows your generator to power your home safely during outages.
Safety Tip:
❗ Never plug a generator directly into a wall socket. It’s illegal and dangerous. Use a certified electrician for a DB board installation.
6. How Long Can Diesel Generators Run?
Most diesel generators are designed for long runtime, making them ideal for prolonged blackouts. Here’s what to expect:
| Fuel Tank Size | Runtime @ 50% Load |
|---|---|
| 20 litres | 8–14 hours |
| 50 litres | 20–30 hours |
| 100 litres | 30–60 hours (depending on load and generator size) |
💡 Many diesel generators include large built-in tanks or can be connected to external tanks for extended use.
7. Real-World Example: Powering a 3-Bedroom House
Appliances running simultaneously:
-
Fridge
-
Lights in 5 rooms
-
Wi-Fi and TV
-
Microwave
-
Washing Machine
-
Laptop chargers
➡️ Total Estimated Load: ±5kW
✅ Recommended Generator: 7.5kVA diesel generator (for safety margin and surge capacity)
8. Frequently Asked Questions
Q: Can a diesel generator power my geyser and oven too?
A: Yes, but ensure you size it appropriately. A 15–20kVA unit can comfortably handle high-consumption appliances.
Q: Is diesel better than petrol for whole-house backup?
A: Yes. Diesel is safer to store, more efficient for long use, and diesel engines last longer.
Q: Can I automate my diesel generator startup during power cuts?
A: Yes, with an ATS (Automatic Transfer Switch) your generator will start and stop automatically with grid outages.
Q: Are diesel generators noisy?
A: Some models can be loud, but silent diesel generators with soundproof enclosures are available and suitable for residential use.
9. Internal Links for Additional Info
Conclusion
A properly sized diesel generator can power your entire home — from essentials to luxuries — offering a reliable solution during South Africa’s unpredictable power grid interruptions. With the right installation and generator capacity, your household can run seamlessly through outages.
Looking for a powerful and reliable diesel generator for your home?
👉 Browse our full range of diesel generators at Africa Power Equipment — trusted for backup power that works when it matters most.