Everything you need for commercial electrical load calculation

Fusion explain how to calculate commercial electrical loads and also discuss other considerations for economic business.

Everything you need for commercial electrical load calculation

Commercial electrical load calculation is essential to operating a cost-effective and efficient business. Increasing your commercial electrical load factor results in lower costs. In this article, we’re going to explain how to calculate commercial electrical loads and also discuss other considerations for economic business.


Put simply, an electrical load is any part of a circuit that uses power. For example, a lightbulb is an electrical load when it comes to your home’s lighting circuit. Similarly, your microwave is an electrical load in your kitchen circuit. Other components that form part of your circuit and use power to do their part also count as electrical loads. For example, motors or resistors.

Electrical load is used as a unit of measurement. Electrical load explains how much power you use and where it is used. This information can be used to set electricity pricing rates by power suppliers. Or, it can be used by electrical engineers to determine the capacity of a circuit.

Commercial electrical load calculation is important to make sure your demand billing doesn’t get out of control.


There are three types of electrical load. These are classified by the way in which they consume energy. The three types are:

○ Resistive

○ Inductive

○ Capacitive

Resistive loads

Resistive loads include some kind of heating element in the component. For example, toasters, ovens, and fan heaters.

Inductive loads

Inductive loads are those that have a motor function. For example, washing machines, dishwashers, and vacuum cleaners.

Capacitive loads

A capacitive load is a type of load used by capacitor components. These components store energy like a battery.


The type of load explains the current pattern you’ll see as the power moves through the component. This can affect how voltage flows through a circuit. It’s important to know where reactance will occur to properly balance a circuit as an electrical engineer.

You also need to have some awareness of electrical load type for commercial electrical load calculation.


In electrical engineering, there are four main types of power system. Each type of power system will use different electrical loads. This affects how a circuit is constructed and balanced by an electrical engineer. As you read on, you’ll realise why commercial electrical load calculation is so different than for industrial, domestic or agricultural power systems.

In different power systems, the volume of power used and the peak times for power usage will be quite different. Imagine the difference in the power used in a home to the power used on a farm, for example. There will be different patterns and different times when power usage surges.

The four main types of power system are:

○ Domestic

○ Commercial

○ Industrial

○ Agricultural

Domestic power systems/domestic electrical loads

Domestic (or residential) power systems are the circuits you’ll find in a normal household. The main components in home circuits will be lighting and appliances.

Power usage in the home varies. Some appliances will be on constantly, like the landline phone or the fridge. Others are used intermittently, such as the radio or a laptop. There will also be ‘peak times’ for power usage, such as at the end of the day when the residents return from school or work.

Commercial power systems

Commercial power systems are used for premises such as shops, schools, and cinemas. Commercial electrical loads include lighting and air conditioning, for example. Unlike domestic electrical loads, commercial electrical loads are usually active for longer periods of time. Consider, for example, that most shops will have their lights on all day every day, while most households only turn on their lights when it starts to get dark.

Commercial electrical load calculation is vital to the running of an efficient and cost-effective business.

Industrial power systems

Industrial electrical loads may be much more varied than domestic and commercial electrical loads. For example, in a factory, you would expect there to be many inductive loads to power machinery and specialised equipment. These items will usually run for many hours a day, often without a break. As you can imagine, the power usage will be very different from a shop or household. There will be a lot more pressure on the electrical circuit.

Agricultural power systems

Agricultural power systems can be highly complex. For example, many agricultural locations will have remote buildings and machinery spread out across a lot of land. This means electrical circuits may need to tap into generators or offer very large grids. Resistive and inductive loads will be common for heating and cooling regulation for animals and crops. Similar to industrial and commercial power systems, agricultural electrical loads may operate for many hours of the day or even remain active permanently.


Calculating commercial load factor is a useful tool for understanding actual energy usage when most power systems will have energy lulls and energy peaks. When you calculate commercial load factor, you create a reliable average for power demand.

How to calculate commercial load factor

There are many reasons you might need to know the load factor of your power system. For example, a power supplier may use this measurement to calculate your billing. Alternatively, an electrical engineer may use this information to help them balance a circuit.

Contact our qualified electrical team for advice about improving electrical efficiency.


Knowing your load factor can help you to optimise your power usage, thereby lowering your electrical costs as you’ve lowered your power demand. For commercial and industrial power systems, this can represent huge savings over time.

The higher your load factor, the better you are spreading your power usage out – and the more money you are saving. For companies to use power economically, they should aim for as high a load factor as possible.

Marty’s Shoe Superstore is only operating at a load factor of 16.11%, which means there is plenty of money to be saved. Generally speaking, load factors above 75% are considered efficient, while load factors under 50% show that a company is not using their energy efficiently and are likely being hit by much higher electricity charges.

Why load factors differ

Companies that operate for longer periods of time will naturally have higher load factors. For example, a factory that has its machines running 24/7 will have a much higher power usage than a shop that is only open 9-5pm. To benefit from savings, you need to figure out the load factor that is optimal for your business.

Commercial electrical load categories

There are different categories of electrical loads in the commercial sector. These matter due to the many regulations governing electrical installation. To be safe and compliant, professional commercial electrical installers should always be used.

Commercial electrical load categories include:

○ Electrical power

○ Data centre equipment

○ IT equipment

○ Air conditioning units

○ Water heaters

○ Lighting

○ Alarm systems


By now, you understand that load factor affects your demand billing. That is to say, if you’re using energy inefficiently – as indicated by a low load factor – then you’re being charged money you don’t need to spend.

To improve your load factor:

○ Ensure you are only using appliances that bear the Energy Star rating.

○ Stagger starting times of appliances that take time to get going, such as grills and shrink wrap machines.

○ Install fluorescent lighting.

○ Make sure you’re not over or under-using your heating system.

○ Schedule work tasks with electricity usage in mind.

○ Avoid using multiple large appliances at the same time.

Contact our qualified electrical team for advice about improving electrical efficiency.


Earlier in this article, we touched upon how domestic, agricultural, industrial, and commercial electrical loads are all different. They’re different not only in their energy usage but in the types of electrical load they use (resistive, inductive, capacitive).

For this reason, a domestic electrician cannot install commercial power systems. The regulations are different, the circuits are different, and even the way the voltage flows is not the same between the different electrical load types.

Take a look at our article on commercial electrical codes in the UK for more information.

How to calculate commercial electrical load

You need to know your commercial electrical load to know which amperage your company needs. Amperage can range from 100-amp to 400-amp. The lower the amperage, the cheaper your billing. That being said, there will be a minimum amperage possible to run your business, depending on how much energy you use. If you overload the system, you can face a complete electrical outage.

To calculate commercial electrical load, you simply need to add together the wattage used when you combine all lighting, appliances, systems, etc. In other words, the wattage used by all commercial electrical loads in your premises.

This can be a time-consuming and confusing process! We suggest making a record in a table.

Contact our qualified electrical team for advice about improving electrical efficiency.

Hiring electrical load specialists for commercial electrical load calculation

At Fusion, we are experts in electrical engineering. We know electrical regulations like the back of our hand.

We operate with technical expertise in multiple sectors, including commercial and industrial. Our engineers know electrical loads are different in each sector and that a one-size-fits-all approach doesn’t work.

Furthermore, we are NICEIC Approved Contractors which means all of our work meets very strict standards of quality and safety, so you can be assured of peace of mind. We are also CHAS accredited (Contractors Health & Safety Assessment Scheme).

Our electrical engineers visit all sites prior to commencing any work to assess your needs, your electrical loads, and your load factor. We can then work with you to create the best installations that are balanced, safe, and efficient.

In addition, we are specialists in electrical maintenance. We can help ensure your electrics are always up to code in industrial and commercial settings.


Engineer carrying out electrical maintenance

Electrical loads are second nature to us. Which other companies can say that? We operate in a niche, which gives us powerful insights into energy and electrical installation. We are the electrical professionals.

For your free site survey, contact us today.

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