Understanding Generator Load Management and Sizing

Power grids are taxed and becoming more and more unreliable. When the power goes out during Ohio’s increasingly common seasonal storms, a standby generator will kick into gear to keep your home or office running smoothly. But it can only make your life easier if it’s properly sized and configured. Choosing the right generator involves understanding both load management and generator sizing, two critical factors that will ultimately determine the performance, efficiency, and cost of the generator you select.

What Is Generator Sizing?

Generator sizing is the process by which your trusted generator installation and maintenance provider is able to determine how much electrical power your home needs during a power outage. Capacity is another term you may hear. This is measured in kilowatts (kW) and is based on the appliances and systems that you want to keep running via your generator when the power goes down.

Proper sizing is essential to selecting the correct models of GENERAC generators. Installing and operating a standby generator with the correct capacity for your specific needs ensures that:

• Your generator can handle demand without overloading
• Essential home or business systems stay powered
• You don’t overspend on unnecessary capacity

Choosing one of the many GENERAC generators that is either too large or too small for your specific needs can pose problems. While an undersized generator may struggle or shut down under a heavy electrical load, an oversized unit can lead to higher costs, both upfront and when it comes to operating expenses over time. For the most reliable performance now and in the future, it is vital to select a generator that is tailored to your power usage.

What Is Generator Load Management?

Load management that is used in GENERAC generators and other models refers to the system that controls how power is distributed throughout your home during an outage. To put it simply, load management controls which appliances run and when, preventing the generator from being overwhelmed. This method may also be known as load shedding, which happens automatically, but users can also opt to define loads according to an assigned priority. Oftentimes a transfer switch plays a part here, allowing the generator to feed power to only a limited number of circuits and appliances.

More often than not, electricity demands are cyclical and shift from one area of the home to another. So instead of running everything at once, generator load management principles prioritize and balance electrical demand to prevent overload and equipment stress or breakdown. Modern standby systems–especially GENERAC generators–typically use automatic load shedding technology to manage this process seamlessly.

It makes sense in theory, but what does this mean in practice? Essential devices and circuits receive priority and remain powered, while others may be shut off as the generator reaches capacity.

Here’s a real-life example:

• Your air conditioner (AC) may temporarily shut off when a high-demand appliance (like an oven or electric water heater) turns on. However, once demand drops (appliance is turned off), the AC automatically resumes operation.

Effective load management ensures that your generator operates as efficiently as possible while also preventing interruption in power supply to critical components and systems.

How Generator Sizing Works

Here’s a step-by-step rundown of how generator sizing works in practice.

Step 1: Identify Essential vs. Non-Essential Loads

Each home or business is unique, and you will have your own set of appliances, circuits and systems that are non-negotiable–you need these to be operational during a power outage. Start by separating what you need, from what you want. 

For homeowners, essential loads could include:

• HVAC systems
• Refrigerator/freezer
• Sump pump or well pump
• Water heater
• Medical equipment

For businesses, essential loads could be any critical systems that are required to maintain safety, security, and core operations during a power outage. These typically include systems that ensure business continuity and compliance with safety regulations, such as:

• Emergency lighting, fire alarm systems, fire pumps, smoke control systems, and security/access control systems
• HVAC systems, water pumps, septic pumps, and elevators
• Data servers, IT/communication systems, and POS systems
• Freezers and coolers to prevent inventory loss
• Medical equipment, surgical suites, and medical gas systems 

Once you have your needs outlined, you can then work with a professional installer of GENERAC generators to include enough capacity to also allow for additional, optional loads.

Non-essential loads for homeowners might include:

• Pool equipment
• EV chargers
• Secondary appliances

Non-essential loads for businesses may include:

• Air conditioning and heating systems that are not required for processes or safety
• Microwaves, coffee makers, vending machines, water coolers, copiers, and printers
• General office lighting or exterior decorative lighting
• Some elevators and non-essential computers
• Production machines that are not critical to operations 

Step 2: Calculate Power Requirements

Once you have a list of the appliances and systems that are must-haves in the event of a power outage, you’ll need to tally up their individual power requirements. This involves understanding the difference between running watts vs. starting watts, along with understanding why starting loads matter for motors.

When electric appliances and systems start up, they often cause a surge in power. This is because the power needed to get running is typically more for larger appliances than the amount of power required for regular operation. This number above typical usage needs to be factored into your eventual total power needs when selecting a standby generator. Air conditioning units, refrigerators, water pumps and other motor-driven systems are key components that commonly require additional power at startup. 

Step 3: Determine Peak Demand

Now that you have all of your numbers in order, and you know which appliances and systems will be supported by your standby generator, you need to determine the absolute peak power demand you could encounter. Envision a scenario, perhaps either in winter or summer, when the HVAC system is running full force, someone is taking a shower, the dishwasher and fridge are running and you’re making dinner in the oven. Or maybe the washing machine is cleaning a load and the dryer is running. Whatever the most common systems that run together in your home that you’ll also want to be operational during a power outage, these are the power demands you’ll need to consider when determining your peak needs.

If you are selecting one of the many GENERAC generators available for commercial or industrial power support, this same advice applies, just according to your business context. And in either residential or business settings, remember that the combined demand you tabulate determines the minimum generator capacity required–it’s always a good idea to add a 25% safety buffer. Another way to get a handle on peak demand is to check utility billing history or conduct a 30-day usage monitor for the safest, most accurate estimate.

To find specific wattage needs for your appliances and systems, you can reference manuals from the manufacturer, get in touch with the manufacturer, or consult the appliance itself–kW needs are often listed on a label along with other model information. You can also consult generic wattage charts available online, or you can consult with a trusted provider of generator installation and maintenance, like the team at Generator Pros.

Benefits of Proper Load Management and Sizing

Choosing a generator that is ideally sized to your power needs and equipped with the proper load management strategies ensures that you are able to buy precisely the capacity you need–not more, not less. This is a more cost-effective option in the long run. A properly sized generator also improves efficiency and reduces fuel consumption, both when in use and during regular operation. When a generator is correctly matched to your needs, it will function optimally as well, which can help to extend its lifespan and prevent avoidable stress and wear and tear. Taken together, all of these factors ensure that a well-chosen standby generator will offer more reliable performance during peak demand and far into the future.

Common Generator Sizing Mistakes

Now that you know what to do and what to look for, it’s just as important to know what to avoid. Here are the most common mistakes that we see when customers are looking for GENERAC generators for their home or business:

• Undersizing: a generator that is too small for the required power needs can cause overloads and outages
• Oversizing: a generator that is too large for required power needs can lead to wasted money and fuel
• Ignoring Starting Watts: a standby generator that doesn’t account for starting watt surge can encounter operational issues and lead to equipment stress and premature breakdown
• Neglecting Future Needs: only considering current needs when purchasing a generator ignores potential future additions to a home or business

Why Professional Sizing Matters

Finding the right size of GENERAC generators for your specific needs while also incorporating potential future additions is a fine balance to strike. Load calculations can be complex and in addition to capacity, you need to ensure code compliance and that key safety requirements are met. That demands proper installation of transfer switches and the unit itself. It’s really best to work with a trained, certified technician who is experienced with the generator you are considering, prior to purchasing. The expert team at Generator Pros has decades of experience and is here to help you to iron out key details and make the right decisions. 

Your Source For Generator Installation and Maintenance

At Generator Pros, we are proud to offer premier models of GENERAC generators to our clients for the best protection against power outages and power quality issues. We handle all phases of electrical work involved with generator installation and maintenance, including repairs, scheduled checkups, and ongoing support. Our industry-trained and -certified crew have been serving Ohio and Pennsylvania communities since 1985. For any and all standby and mobile generator related needs for residential, commercial and industrial applications, look no further. Contact us to get started on your custom assessment today!