Choosing the right home standby generator is about more than matching the generator's kW rating to your home's mains power supply. A common misconception is that an 8kW mains supply automatically means you need an 8kW generator. In reality, your generator may need to be larger depending on the appliances, motors and electrical equipment you want to run.
Understanding your home's power requirements, generator fuel type, noise level, installation location and automatic transfer requirements will help you choose a reliable backup power solution that is suitable for your property.
How Much Power Does a Home Standby Generator Need?
The first step when choosing a home standby generator is calculating the electrical load you need to support. Simply matching your generator's rated output to your home's mains connection is not always enough.
Equipment such as air conditioners, electric gates and doors, refrigerators, dishwashers, water pumps and electric motors can require significantly more power when starting than they use during normal operation. Depending on the equipment, starting power can be substantially higher than its rated running power.
This is why a home standby generator should be sized according to the equipment you intend to operate, including both running wattage and starting or surge requirements.
If you are unsure how to calculate your home's electrical load, ask a qualified electrician to assess your requirements. They can help identify which appliances need to operate during an outage and determine an appropriate generator capacity.
Can You Use a Smaller Generator During a Power Outage?
Yes. If your generator is intended strictly for emergency backup, you may be able to reduce the required generator size by deciding which appliances and systems are essential during a power outage.
For example, you may choose to prioritise refrigeration, lighting, security systems, water pumps and selected heating or cooling equipment while leaving non-essential appliances switched off.
However, it is important not to undersize a generator simply to reduce the initial purchase price. Homes are becoming increasingly dependent on electrical appliances and equipment, so choosing a generator with some additional capacity can provide greater flexibility for future requirements.
What Fuel Type Is Best for a Home Standby Generator?
Home standby generators are commonly available with petrol or diesel engines. The right fuel type depends on how you intend to use the generator, your existing fuel arrangements, expected operating hours and installation requirements.
Petrol Generators
Petrol generators can offer a lower initial investment and are well suited to shorter-duration emergency backup applications. They can also be a practical option for homeowners who already use petrol-powered equipment.
For occasional backup use where the generator only needs to operate for a limited period, a petrol model can be a cost-effective solution.
Diesel Generators
Diesel generators are well suited to applications where extended operating times and continuous power are important. They are commonly used for demanding commercial, industrial and standby applications where the generator may need to operate for long periods.
Diesel generators are available across a wide range of capacities, making them suitable for everything from smaller backup systems through to large commercial power requirements.
If a diesel generator is expected to operate in very cold conditions, particularly around or below 0°C, appropriate cold-start or preheating equipment may be required depending on the engine and installation.
How Important Is Generator Noise Level?
Noise is an important consideration when installing a generator at a residential property. Like any engine-driven machine, a generator produces mechanical and exhaust noise while operating.
Generator noise is commonly expressed in decibels (dBA), with measurements often specified at a distance such as 7 metres. When installing a generator in a residential or built-up area, choosing a suitably enclosed or sound-attenuated model can help minimise disturbance.
Where possible, avoid installing an open-frame generator directly in a residential outdoor environment without appropriate protection and consideration of exhaust, ventilation and noise requirements.
A silent or enclosed generator can be a better choice where reduced operating noise and weather protection are important considerations.
Where Should a Home Standby Generator Be Installed?
The installation location is another important factor when choosing a standby generator. Generators may be installed outdoors in an appropriate location or, where permitted and properly designed, within a dedicated enclosure or plant room.
If the generator is installed outdoors, make sure the generator enclosure is designed for outdoor conditions and provides suitable protection from weather exposure.
Open-frame generators should not simply be placed inside a garage, shed or other enclosed space. Engine exhaust contains carbon monoxide and other combustion gases that can be hazardous or fatal. Indoor generator installations require professionally designed ventilation and exhaust systems.
A suitable generator location should:
- Provide sufficient space around the generator for servicing and maintenance.
- Allow adequate airflow for engine cooling and combustion.
- Provide a correctly designed exhaust system where applicable.
- Keep exhaust gases away from people, windows, doors and air intakes.
- Protect the generator from flooding and excessive water exposure.
- Keep the generator away from fuel, flammable materials and chemicals.
- Prevent unauthorised access to the equipment.
- Provide adequate access for delivery, installation and future servicing.
Always follow the generator manufacturer's installation requirements and have fixed standby generator installations completed by appropriately qualified professionals.
Why Is Generator Location Important?
Generator location can be overlooked when planning a backup power system. Before purchasing a generator, consider how the unit will physically reach its final installation position.
Large generators may need to be transported through gates, doorways, stairwells or other restricted access points. Checking these requirements before purchase can prevent expensive installation complications later.
The site should also be assessed for potential flooding, drainage, ventilation, exhaust discharge and access for routine maintenance.
What Is an Automatic Transfer Switch (ATS)?
An Automatic Transfer Switch (ATS) allows a standby generator to become part of an automatic backup power system. When a mains power failure is detected, the system can start the generator and transfer the selected electrical loads from the utility supply to the generator.
This means the homeowner does not necessarily need to be present to manually start the generator during a power outage.
Depending on the system, generator start-up and transfer can take a short period of time. The exact sequence and transfer time depend on the generator, ATS and installation configuration.
ATS equipment is available for different installation environments, so the switchgear must be selected to suit the generator and installation location.
Does an ATS Affect Generator Sizing?
Yes. When a standby generator automatically restores power, several electrical loads may reconnect at approximately the same time. This can create a significant temporary demand on the generator.
If the generator is undersized, the additional starting load can cause an overload or prevent the generator from successfully supporting the connected equipment.
This is why generator sizing should consider not only the normal running load but also motor starting currents, surge requirements and the way loads are restored during a power outage.
A manual changeover switch can also be considered for some applications. It can provide a straightforward and cost-effective way to connect selected circuits to a portable or standby generator, subject to correct electrical installation.
Discuss the best changeover arrangement with your electrician or generator supplier based on your home's electrical system and backup requirements.
How Do You Maintain a Home Standby Generator?
Like any engine-powered machinery, a generator requires regular maintenance to remain reliable when you need it most.
Routine servicing should follow the manufacturer's recommended maintenance schedule and may include checking engine oil, filters, battery condition, fuel system components, cooling systems and other service items.
For standby generators that may sit unused for extended periods, regular testing is particularly important. A scheduled test run can help identify starting, battery or fuel-system problems before an actual power outage occurs.
Proper maintenance can significantly improve generator reliability and help extend the working life of the equipment.
What Should You Consider When Choosing a Home Standby Generator?
Generator capacity is only one part of the decision. Before purchasing a home standby generator, consider:
- Power output: Calculate your running and starting power requirements.
- Fuel type: Consider petrol or diesel based on your application and expected operating hours.
- Noise level: Choose an appropriate generator enclosure for residential environments.
- Installation location: Allow sufficient ventilation, exhaust clearance, access and weather protection.
- Transfer method: Determine whether an automatic transfer switch or manual changeover system is appropriate.
- Essential loads: Identify which appliances and circuits must remain operational during an outage.
- Future requirements: Consider whether your home's electricity demand may increase over time.
- Maintenance: Make sure servicing and replacement parts are readily available.
- Professional installation: Fixed standby generator systems should be correctly installed and connected by qualified professionals.
Frequently Asked Questions About Home Standby Generators
FAQs
What size generator do I need for my home?
The required generator size depends on the appliances and electrical equipment you need to operate during a power outage. You should calculate both their running and starting power requirements rather than simply matching the generator to your home's mains supply.
Is an 8kW generator enough for a house?
An 8kW generator may be suitable for some homes but not others. The correct size depends on the electrical loads you want to run, particularly appliances and motors with high starting power requirements.
Is petrol or diesel better for a home standby generator?
Neither fuel type is universally better. Petrol generators can be suitable for shorter-duration emergency backup, while diesel generators are often preferred for applications requiring extended operation and high durability. Your expected usage and installation requirements should determine the best option.
Can a home standby generator run an air conditioner?
Yes, provided the generator has sufficient capacity to handle the air conditioner's running and starting requirements. Air conditioning systems can have significant starting demands, so these must be included when sizing the generator.
Do I need an automatic transfer switch for a standby generator?
Not necessarily. An automatic transfer switch provides automatic changeover between mains electricity and generator power, while some systems use a manual changeover switch. The appropriate solution depends on the generator and electrical installation.
Can a standby generator be installed indoors?
Generators must not be operated in enclosed spaces without a professionally designed installation that provides suitable ventilation and exhaust gas management. Carbon monoxide from engine exhaust is extremely dangerous. Always follow the manufacturer's installation requirements and applicable electrical and building regulations.
Find the Right Home Standby Generator with Riequip
Choosing the right home standby generator requires more than selecting a kW rating. Your running load, starting power requirements, fuel type, noise level, installation location and transfer system all need to be considered.
If you're unsure which generator is right for your home, the team at Riequip can help you understand the available options and identify equipment suited to your requirements.
Need help choosing a generator? Call Riequip on 0800 378 478 or get in touch with our team to discuss your requirements.
You can also explore our range of generators and find a reliable power solution for your home or property.
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