How to calculate the required power of your residential electrical panel

Generally speaking, an electrical panel will break down when its power is too low for your energy use. It is therefore essential to calculate the power you need to supply your house or building before choosing a device or a supply. This will prevent you from untimely disconnections while you go about your daily business.

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What is the power of an electrical panel?

The power of an electrical panel is the maximum amount of electricity that can be used at any one time in a building or residence. It is expressed in kVA (kilovoltampere) or kW (kilowatt).

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In other words, if your electrical panel is rated at 6 kVA, the total amount of electricity you can use at one time is 6 kW. Otherwise, the device may trip, resulting in a power outage that can damage your appliances.

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How to calculate the power you need for your electrical panel?

The power you need for your electrical panel depends on several factors:

• The living area of the building;
• Electrical appliances;
• Lighting;
• Heating devices.

1- Make a list of the appliances you use and their power

To start, you must list all the devices you have and their power. Here is an illustration:

• Heating device: 70 W/m² for 100 m²;
• Iron: 400 W ;
• Washing machine: 2 500 W ;
• Dishwasher: 750 W ;
• Refrigerator: 500 W ;
• Lighting: 40 W per room for 3 rooms;
• Other electrical accessories: 50 W.

2- Calculate the amount of electricity used if all appliances are running simultaneously

Next, you need to calculate the amount of electricity used if all the appliances are running at the same time. For our example, it is (70 x 100 + 400 + 2500 + 750 + 500 + 40 x 3 + 50) W = 11,320 W, or 11.32 kW. Therefore, the power you need for your electrical panel is around 12 kW.

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3- Make adjustments according to use

You can make adjustments by assuming that you do not use all the devices at the same time. In fact, only the heaters and refrigerator run at the same time and should be included in the calculation. On the other hand, it is possible to arrange your schedule so that the dishwasher, washing machine and iron do not run simultaneously. In this case, the power requirement would become (70 x 100 + 2500 + 40 x 3 + 50) = 9670 W, or 9.67 kW.

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Conclusion

In short, you need to have an estimate of how you use your appliances and lighting devices in order to calculate the power required for your electrical panel. In general, it varies from 3 to 12 kW for a residence and from 12 to 36 kW for a commercial building.

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