How To Calculate Safe Electrical Load Capacities

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It's hard to know how much electrical load your home can handle. You might overload a circuit and cause a fire, or worse.  You could be putting your life and property at risk by using too many high-powered appliances at once.

With so many devices drawing energy from the grid, it's important to understand your home's electrical load capacity. This will help you plan and manage the distribution of electricity throughout your house. Keep reading to understand how to calculate your home's electrical load capacity.

What Is Electrical Load Capacity?

Electrical load capacity is the total amount of current a wire can handle. The total electrical capacity of the electrical service panel is measured in ampere or amps. When making significant additions to your home, you should calculate the electrical load capacity on anything that runs on electricity in your home.

What Is Electrical Load Capacity?
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The electrical load is measured in wattage or watts, or hours. The electrical load capacity is the total electrical current your household wiring can handle. For example, if you have a refrigerator rated at 600 watts, and a light fixture with two 60-watt bulbs, your wiring circuit's total electrical load capacity cannot exceed 1200 watts or 12 amps.

The national electrical codes are the basis to ensure that wiring is safe and meets safety requirements for a given location. The national electric code recommends that individual branch circuits in a modern residence be at least 40 amps, equivalent to eight standard 15 amp outlets per circuit.

Importance of Electrical Load Calculation

Finding the correct electrical load capacity by adding all the wattages for appliances and devices. Not only will they be affected if you overload your circuit, so will your safety. By finding the electrical load, you'll also be able to determine whether you have to change your electrical service.

It will also tell you the power supplied in the home isn't enough for your electrical use. The electrical service is commonly measured in amps, and you can find the amount provided on your electrical power bill, stating that it's 120 volts, 20 amps.

To avoid overload, the best-licensed electricians recommend dedicating single circuit appliances that consume so much energy, such as refrigerators, washing machines, air conditioners, and dishwashers. You can avoid spending money on repairs due to overloading by having basic knowledge in calculating your electric load.

How to Calculate Electrical Load Capacity

Different homes need different amp services, and you can use a bit of math to figure out what kind of electrical load your home requires. For instance, a 60-amp service is probably inadequate for a modern home, while a 100-amp service is good for a home not less than 3000 square feet that don’t have central air conditioning or electric heat.

How to Calculate Electrical Load Capacity
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A home larger than 2000 square feet with central air conditioning or electric heat needs a 200-amp service.

How to Find Electrical Load Capacity

Calculating electrical load for your home needs you to calculate the amperage load of all the various appliances and light fixtures. Find the total wattage of all the appliances and devices plugged into a circuit breaker box by consulting their labels.

If you want to check your home's circuit load without finding out its wattage, use an electric load calculation cord available for purchase at hardware stores. If you have an electrician install it, then they can show you how to find your circuit breaker box-s amperage and calculate the wattage of each appliance or device on the electrical circuit.

Once you know how many amps your load calculation reads, multiply it by 120 to find its voltage and then multiply that number by the amperage of each appliance you plan into that circuit. If your total is higher than the circuit's capacity, then unplug one or more devices before it can safely deliver power where your family needs it.

The electrical circuit works like how the water flows from a pipe. The water pressure is in volts, and the water flow rate is in the amps. The water wheel represents watts which depend on the pressure. You can use these formulas to calculate individual circuit's capacity, electrical loads, and the entire electrical service panel.

How to Add Capacity to Your Electrical Load

Installing a new circuit isn't that difficult but ensure your service panel can handle the extra load. This is because a circuit panel with too many circuits can be dangerous. Fuse boxes rarely have space for new circuits, so replace the fuse box with a circuit breaker if you have a fuse and need a new service.

If there's a slot in the breaker box, you can remove an open space and install a new breaker. The capacity of your box depends on the circuit breaker rating label. If there's no open space, the local electrical codes might allow you to replace a single breaker with a tandem breaker.

Electrical Load Box Sizes

The size of your electrical load box will determine your home electrical capacity. Here are the three categories of electrical load boxes:

Small Fuse Box

A small fuse box might be found in older homes. They are small enough to fit into a standard low-rise electrical box. They can accommodate single or tandem circuit breakers and offer limited electrical wiring space. It can supply only one 240-volt appliance such as an oven and clothes dryer.

Medium Sized Service Panel

You might find this electrical load box in homes built before electric dryers became common appliances. The fuse box can supply power for up to three 240-volt appliances such as clothes washers, stoves, and dryers. It's also the minimum panel amperage required by the national electrical code.

Large Service Panel

This electrical load center has even more room for wiring and breakers. This type of fuse box might be required in a home that uses large electrical appliances and includes heating and air conditioning equipment. Upgrading to this fuse box can give you more flexibility to use more circuits without worrying about overloading the system.

Large Service Panel
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How to Inspect a Service Panel

An electrical service panel should be located where adults can get to it easily and children can't. Ensure you firmly attach any exposed cable to the sides of the panel and clamp it tight to the knockout holes. Inspect all connections for corrosion or loose wires. 

If a 14-gauge wire is connected to a 20 amp breaker or fuse, replace the breaker with one that's 15 amps to prevent the wire from overheating. And if you find a hopeless tangle, call a qualified electrician for an evaluation. Call professional repair right away if you also find melted or nicked wire insulation.

FAQs on How to Calculate Safe Electrical Load Capacity for a Home

How do you calculate electrical panel load?

You calculate the total load on the breaker panel by adding the amperage ratings from each circuit breaker then multiply that sum by 120 volts.

Final Thought on Calculating Electrical Load Capacity for a Home

As you can see, calculating your home's electrical load capacity is necessary, especially if you're planning to buy new appliances or extend your electrical load. This is helpful for you to avoid appliances damage and possible danger in the future.

 

 

Kristina Perrin

Kristina Perrin

Kristina is an expert DIY home remodeler and mom to three. When she's not cooking or experimenting with new recipes, you can find her working on new home improvement projects or writing about her favorite kitchen appliances or DIY projects on Kitchen Infinity blog.

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