Evaluating your home’s electrical load is important for avoiding issues with your electrical system and preventing safety hazards. It’s equally important to know the total load capacity of your electrical system and the capacity of each of your electrical circuits.
Why Electrical Loads and Load Capacities Matter
Electrical load refers to the total power draw on a single circuit or across the home’s electrical system. Electrical load capacity is the maximum amount of power a circuit or an electrical system can supply. If the total load on a circuit exceeds the circuit’s load capacity, the circuit breaker gets tripped. This safety measure prevents an electrical fire from potentially occurring as a result of the circuit being overloaded.
You can also cause the main breaker in your electrical panel to trip if your current load exceeds your electrical system’s maximum load capacity. However, what more commonly happens is that less power flows through some of the circuits. This often causes some of the home’s lights to flicker since they aren’t receiving as much power as they should.
How to Calculate Electrical Load Capacity
The electrical load capacity of a circuit or an electric system tells you how many total watts of electricity it can supply. The maximum wattage is determined based on the amperage of a circuit or the amperage of a home’s electrical service panel. In the US, the electric grid operates on 120/240-volt power. The power coming into the house is 240 volts, but most circuits are only 120 volts. The exception is the dedicated circuits for appliances like an air conditioner or clothes dryer, which operate at 240 volts. When looking at an individual circuit, you can calculate the maximum wattage by multiplying the voltage and amperage of the circuit. For instance, a 20-amp, 120-volt circuit has a total load capacity of 2,400 volts. If you have a 100-amp electrical service panel, it means the load capacity of your entire electrical system is 24,000 watts.
How to Calculate Electrical Loads
The main reason for knowing the current electrical load and total load capacity of any circuit in your home is to avoid overloading the circuit and causing its breaker to trip. Knowing your electrical system’s total load and load capacity is also important for avoiding overloads and potential safety issues. You can also determine if your electrical system can support additional loads. For instance, if you want to install something like an EV charging station or are putting an addition onto your house, you need to know if your electrical panel is large enough or if you need to upgrade to a new electrical panel. You generally want to make sure that your current load never exceeds 80% of a circuit’s total capacity or that the total load in your home is never above 80% of your electrical panel’s total capacity.
Calculating the load of a single circuit is quite easy. Add up the wattage of your light bulbs and whatever you have plugged in and turned on to determine the total current load. This lets you know whether you can also plug in something like a vacuum to that circuit without overloading it.
Calculating your entire home’s electrical load is a bit more difficult and is usually something you’ll need to have a professional electrician do. The reason it’s difficult is that the load continually fluctuates based on how many appliances, electronic devices, and lights are currently on. This is why electricians use a formula that enables them to estimate what your maximum load would likely ever be at any one time.
The formula estimates the load for the home’s lighting and outlets on the 15-amp circuits. This is done by averaging 3 watts for every square foot. The electrician then adds up the wattage of all of the 20-amp circuits and the wattage for all of the major appliances. This tells them the maximum total load. They subtract 8,000 volts from the total wattage to calculate the average potential load because only the first 8,000 watts are factored in at 100%. They then only factor in 40% of the remaining maximum load above 8,000 watts, which gives them the average potential load at any given time.
If you need an experienced residential and commercial electrical contractor in Forest Lake or the Twin Cities area, Plugz Electric has you covered. We offer expert installation, repair, and maintenance services. We can also help if you need to have a load calculation performed to determine if you need to upgrade your electrical panel. To schedule an inspection and load calculation or any other service, contact us today.
