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When planning changes to building infrastructure, you must understand the current electrical layout of the building and its capacity.
In simple terms, spare capacity is the amount of additional electrical load your building can safely support before the system reaches its limits.
The formula for figuring out the spare capacity is:
Incoming Supply Capacity – Existing Demand = Spare Capacity
Knowing the capacity of your building can help you plan upgrades and extract maximum efficiency from the system without risking electrical faults.
Whether it is an office space, a shop, a retail store, or a rental, the importance of a properly functioning electrical system cannot be overstated.
Read on to find out all about how to figure out how much spare capacity your building has and how to manage it effectively:
From the outside, any building can appear to have plenty of power because of its extensive use of lights, sockets, and equipment that apparently work normally.
However, if you look closely, you will find out that the electrical infrastructure could already be operating close to its maximum limits.
Spare capacity is influenced by several factors such as:
If the building operates normally without faults, it usually indicates that there are no demand and supply issues within the electrical system, but if you notice flickering, burnt-out equipment, and fluctuations, then this might indicate that you have low spare capacity and may need to plan upgrades.
Spare capacity isn’t just a nice-to-know number that you keep in the back of your mind. For growing businesses, it’s a reality that needs to be always accounted for when the business is being expanded.
Unfortunately, spare capacity is also rarely explored by inexperienced electricians who are usually only focused on blindly finishing the job at hand.
Failing to account for spare capacity and load limits can lead to losses, downtime, and even damage. All these things can cause friction during expansion and may even cost the business more time and money down the road.
Typically, businesses realise limitations when it’s too late, and in most cases, the conversation around spare capacity arises when the business installs:
Infrastructural expansion done on a limited load can result in damage and losses of new equipment, which can also lead to downtime. This is why business owners need to consult with a professional installation company like Calder Electrical before executing expansion plans.
Qualified electricians don’t just look at the current capacity numbers, but they also take an active part during the expansion discussions of the business.
Typically, electricians may review the following:
The maximum demand is the actual electrical consumption during peak periods. A growing business may have a large supply but low actual usage, meaning significant capacity may be available.
However, knowing how much spare capacity or headroom you have is important because it allows you to plug in new equipment into the current ecosystem without problems.
In most cases, especially with businesses already running heavy equipment, buildings may already be running at a chokehold, and adding more load just adds to the problem.
Usually, the problems aren’t immediately apparent. However, the added stress on top of the maximum load can accelerate the depreciation of electrical equipment. So, given enough time, these systems are bound to fail and may result in damage or, worse, fires and accidents.
Professional electricians review existing equipment and calculate expected future demand based on the plans shared by the business owners.
Installation companies aim to keep enough breathing room to ensure that everything runs smoothly even if a few more pieces of equipment are installed.
To do this, load calculations are done to figure out the current capacity and where the building needs to be in the next 5 years.
As mentioned above, the formula for load calculation is:
Incoming Supply Capacity – Existing Demand = Spare Capacity
For example, if the existing building demand is 120kVA and the incoming supply capacity is 250kVA, then the approximate spare capacity will be around 130kVA (250kVA – 120 kVA)
Good electrical systems are designed to be modular, meaning that you can add to the system later if you plan to expand. However, capacity is not only about available power; if your system is old, then it may require upgrades before additional load can be added.
Several signs show that your building may be running out of capacity, such as:
If these signs occur, then it’s high time you have the system investigated. Please keep in mind that even with good systems, you are bound to revisit the infrastructure before expanding it.
Without proper planning, businesses may face delays to expansion projects, unexpected electrical upgrade costs, equipment downtime, and even compliance issues, which can lead to failed insurance or safety inspections.
The answer to this question is highly subjective. There is no universal figure, but there are a few best practices that help businesses plan for future growth.
The idea behind maintaining a healthy spare capacity is to establish a reasonable margin rather than designing a system that is already near its maximum capacity.
Too much spare capacity can result in business owners spending more than they need to for their current expansion plans, while too little can result in electrical problems.
The safe zone is to stay in the middle and keep just enough headroom to help your business grow without hindrance.
Here are the main upgrades that electricians will consider when optimising the spare capacity for your building:
The first step is to consider the incoming supply to the building.
This is a good place to start because spare capacity is based on simple math. If you need more to come out the other end, then you need to put in more at the front end.
The incoming supply capacity upgrade checks whether the existing electrical supply is adequate for your business’s expansion plans.
For example, if you run a restaurant and want to expand by installing new heavy equipment in the kitchen or developing a separate test kitchen, then you will need a major increase in load since a typical large-scale restaurant will have high-load appliances that work non-stop during business hours.
Professional electricians will look at the following for increasing the spare capacity:
Wiring is the artery of your electrical system. If the arteries are clogged due to damage or if the supply load is too much for them to handle, then you will run into issues. This is especially important for older buildings that often fail modern compliance standards.
Rewiring may not directly increase the spare capacity, but it has a significant impact on the efficiency of the electrical system.
A common reason to revisit wiring requirements for transitioning buildings can be due to rubber or VIR cabling that can degrade over time. These buildings may also not have RCD protection and have undersized circuits, which can add to the problem when operating at maximum.
Electricians will consider the following upgrades when revisiting the wiring system for the building:
The distribution board systems or consumer units are key in managing spare capacity for your building.
If you are planning to expand your business, you may need to go over the current and intended specifications for the electrical system.
In the case of upgrades, old fuse boards are commonly replaced because they usually lack modern RCD protection and cannot handle additional circuits.
Why is this important? Well, the first reason is efficiency and safety, and the second is insurance.
Insurance companies may reject outdated equipment and may even charge you higher premiums based on the overall health of your electrical system, especially if the system shows issues after expansion.
If your business is in an old building, then it would be a good idea to go with modern upgrades, which include metal-clad consumer units that offer superior protection and surge protection devices.
There is more than one way to increase the spare capacity. Energy efficiency is one of the most important aspects of running any business because it directly lowers costs and boosts the business’s bottom line.
Growing businesses can consume a lot of energy, which is why you will need to install an efficient system that is designed for maximum output with minimum input, thereby increasing the spare capacity of the building.
This makes the business more feasible and allows the owners to expand with full confidence, knowing that their building can handle the additional load.
Energy efficiency is also a top priority for most professional electricians. After all, it gives the business owners a two-for-one deal where you get savings and increased capacity and efficiency.
Simple changes such as going with energy-saving LED lights and equipment or installing inverter-based equipment that runs with variable voltage requirements can go a long way.
If you want to take savings to the next level, then you may also install a solar system for your business.
A solar system can not only increase the spare capacity of the building but also help you get a good handle on the actual consumption thanks to modern metering and AI-powered monitoring devices that come with good solar installations.
This way, you can know exactly how much you are spending and saving and where you can save even more. It can also allow business owners to install new equipment and monitor their impact on the system over time.
Additionally, businesses can also increase spare capacity and savings by exploring the following changes:
When you expand your business, you will often have to take on green initiatives to strengthen your brand image in the public eye.
There are several ways to do this; the most popular method is going the solar route. Solar installations are becoming popular because they help reduce the carbon footprint and drive down costs for businesses. As we have already mentioned, it’s a two-for-one deal!
You can even add value to your business by going with a spot for EV charging. Of course, this addition impacts the spare capacity, but the change is nuanced.
Professional installers look to offset the EV charging load by installing an adequate system. For example, a typical EV charging spot consumes anywhere from 7 kW to 22 kW of active power for slow AC charging and between 50 kW and 350 kW for rapid fast charging.
At this rate, a standard public commercial charging spot can draw up to between 600 kWh and 1,500 kWh of electricity per month. This can negatively impact the spare capacity unless you offset it with a system that accounts for this change.
For growing businesses, starting with just one charger is the best way to go forward because it allows you to assess the customer reaction, sentiment, and footfall. If the numbers are favourable, then you can expand accordingly by adding more panels and installing adequate load balancing systems to maintain spare capacity.
Wiring and electrical installations are tasks that require a certain skill set to be performed successfully. When hiring an electrician to plan and conduct a full electrical installation for your property, make sure that they are fully certified, qualified, and that they understand your requirements.
At Calder Electrical, we have been providing electrical services to residential, commercial, and industrial properties for over 40 years and are specialists in all aspects of electrical installations, maintenance, and testing.
All our work is fully insured, and we work to meet the standards set by the NICEIC to make sure all your electrical installations meet the current regulations, and all the notifiable work is signed off by the local authorities.
Our team can generate a Visual Inspection Report (VIR) to identify anything visual that does not comply with the standards or looks unsafe, as well as a full Electrical Installation Condition Report (EICR), where we will identify and test each circuit to make sure they are not deteriorating and are safe for use within the current standards and regulations set by the BS 7671.
We can also provide PAT testing of appliances to make sure that any items such as kettles, computers, and microwaves are safe for use in the home and workplace.
If you have unplanned issues within your home or business, we can provide a call-out service to rectify and solve any problems, such as circuit tripping, loss of power, broken items that need repairing, or to check if you feel something is unsafe or a potential hazard.
Contact us here or call us at 0800 612 3001 to get in touch with our professional electricians for more information on how to plan an electrical installation for a property and how much spare capacity your building has.
Photo by mostafa mahmoudi on Unsplash
