The main electrical service delivered to your house from the electrical utility company has a total available capacity, measured in amps, or amperes. Most homes have an electrical service of between 100 to 200 amps. Amperage is a measurement of the volume of electricity flowing through wires, and this measurement can vary between 30 amps in very old homes that have not been updated to as much as 400 amps in a very large home with extensive electric heating systems.
Knowing the size of a house's electrical service can help you know if an update is needed or if the service is large enough to handle an update, such as a remodeled kitchen or room addition.
The 400 amp service is usually required for larger homes that demand more heating and air conditioning capacity, as well as homes that utilize jetted tubs, hot tubs, saunas, or other large demand appliances and equipment.
A 100-amp service is good for a home of less than 3,000 square feet that does not have central air-conditioning or electric heat. A home larger than 2,000 square feet that has central air-conditioning or electric heat probably needs a 200-amp service. Use the equation listed above to deduce exactly how many amps your home needs.