One of the most common questions homeowners ask when considering a panel upgrade is how many amps they actually need. The answer depends on the size of your home, the appliances you use, and what you plan to add in the future. Getting this right matters because an undersized panel creates safety risks and limitations, while an oversized panel means paying for capacity you will never use.
For homeowners in Aiken, SC, the decision usually comes down to choosing between 100-amp, 200-amp, or in some cases, 400-amp service. Here is a practical breakdown of each option, what it supports, and how to determine which one is right for your home.
Understanding Amp Ratings
Before comparing panel sizes, it helps to understand what the amp rating actually means. The amperage rating of your electrical panel indicates the maximum amount of electrical current that can flow into your home from the utility at any given moment. Think of it like the diameter of a water pipe: a larger pipe allows more water to flow through at the same time.
A 100-amp panel can deliver up to 100 amps of current simultaneously across all circuits. A 200-amp panel can deliver up to 200 amps. A 400-amp panel, which actually consists of two 200-amp panels, can deliver up to 400 amps.
It is important to understand that you are rarely using the full capacity of your panel at any one time. Most homes use a fraction of their panel's rated capacity during normal operation. The rating represents the peak capacity, which accounts for those moments when multiple high-draw appliances are running simultaneously, such as the air conditioning, electric dryer, oven, and water heater all operating at the same time.
The NEC requires that your panel's rating be sufficient to handle the calculated electrical load of your home, with appropriate safety margins. An electrician performs this calculation, called a load calculation, by adding up the power requirements of all your appliances and circuits and applying the NEC's demand factors.
100-Amp Service: When It Is Enough
A 100-amp panel was the standard for residential construction from the 1960s through the 1980s. For the homes of that era, which typically had gas heating, gas water heaters, gas cooking, and fewer electrical devices, 100 amps was adequate.
Today, a 100-amp panel may still be sufficient for a specific set of circumstances. If your home meets all of the following criteria, 100 amps might be enough:
Small to medium-sized home. Generally under 2,000 square feet, with a modest number of circuits and outlets.
Gas appliances. If your home uses natural gas or propane for heating, water heating, cooking, and clothes drying, the electrical demand is significantly lower than an all-electric home. Gas appliances use only a small amount of electricity for controls and ignition, while their electric equivalents can draw 20 to 50 amps each.
No plans for major electrical additions. If you do not plan to add an electric vehicle charger, hot tub, pool equipment, workshop with heavy tools, or other significant electrical loads, your existing 100-amp service may continue to serve you adequately.
No central air conditioning or a small system. Central air conditioning is one of the largest electrical loads in a home. A typical 3-ton residential AC unit draws approximately 15 to 20 amps at 240 volts. If your home does not have central air, or has a small, efficient system, 100 amps may still be workable.
However, even in homes where the current load fits within 100 amps, there is an important consideration: future flexibility. Upgrading from 100 to 200 amps during a panel replacement adds only a modest amount to the overall cost, while the capacity difference is substantial. Many homeowners who choose to stay at 100 amps find themselves needing to upgrade again within a few years when they add an appliance or make a change they did not anticipate.
200-Amp Service: The Modern Standard
A 200-amp panel is the current standard for residential construction and the most common upgrade for older homes. It provides enough capacity for the vast majority of residential electrical needs, including the loads that modern homeowners consider essential.
A 200-amp panel comfortably supports:
Central air conditioning. Even a large 5-ton system with a heat pump can run alongside other major appliances on 200-amp service without approaching the panel's capacity.
Electric water heater. A standard 50-gallon electric water heater draws about 18 to 25 amps at 240 volts. A tankless electric water heater can draw considerably more, sometimes 100 amps or more for a whole-house unit, but even this is manageable on a 200-amp panel with proper load planning.
Electric range and oven. A typical electric range draws 30 to 50 amps, which is well within the capacity of a 200-amp panel alongside other household loads.
Electric dryer. A standard electric dryer draws about 24 to 30 amps at 240 volts.
Electric vehicle charger. A Level 2 EV charger, which is the type most homeowners install for overnight charging, typically draws 30 to 50 amps at 240 volts. A 200-amp panel can accommodate one EV charger alongside normal household loads for most homes.
Modern kitchen appliances. Dishwashers, garbage disposals, microwaves, and other kitchen circuits all fit comfortably within a 200-amp panel's capacity.
Home office equipment. Computers, monitors, printers, and networking equipment add relatively modest electrical loads that a 200-amp panel handles without difficulty.
For the average home in the Aiken area, 200-amp service provides ample capacity for current needs and enough headroom for typical future additions. This is why we recommend 200-amp panels for most residential panel upgrades. It is the sweet spot between adequate capacity and reasonable cost.
Signs You Have Outgrown Your Current Panel
If you currently have a 100-amp or 150-amp panel, there are several warning signs that indicate you may be pushing its limits:
Breakers trip frequently. If you regularly trip breakers when running multiple appliances, your panel may be struggling to handle the load. This is especially common when the air conditioning is running and someone turns on the dryer or uses a high-draw kitchen appliance at the same time.
You use extension cords or power strips extensively. If you are relying on extension cords and power strips because you do not have enough outlets or circuits, your electrical system may need more capacity. This is a symptom of an undersized panel with too few circuits.
Lights dim or flicker when appliances start. When a large appliance like an air conditioning compressor starts up, it draws a brief surge of current. If your lights dim noticeably when this happens, it can indicate that the panel is near its capacity and the voltage is sagging under the load.
You cannot add the appliances you want. If an electrician has told you that your panel cannot support a new appliance such as an EV charger, hot tub, or workshop equipment, a panel upgrade is the solution.
Your panel is full. If every breaker slot in your panel is occupied and you need additional circuits, you have outgrown your panel's physical capacity even if the amperage might technically be sufficient.
400-Amp Service: When Bigger Is Necessary
A 400-amp service is not a single 400-amp panel. It consists of a 400-amp meter base that feeds two separate 200-amp panels, each with its own main breaker. This configuration is used when the total electrical load of the property exceeds what a single 200-amp panel can support.
In the Aiken area, we see 400-amp service most commonly in the following situations:
Large homes with all-electric systems. Homes over 3,500 to 4,000 square feet that use electricity for heating, water heating, cooking, and drying have substantial electrical demands. When you add central air conditioning, a pool or spa, and multiple high-draw appliances, the total load can exceed 200 amps.
Homes with detached workshops or outbuildings. If you have a workshop with welders, air compressors, or other industrial-grade equipment, the workshop alone may require 100 amps or more. Combined with the house's demand, this can push total requirements beyond 200 amps.
Multiple electric vehicles. If your household has two or more electric vehicles and you want to charge both simultaneously at Level 2 speeds, the additional 60 to 100 amps of charging load may require 400-amp service.
Homes with pools, hot tubs, and extensive outdoor equipment. A pool pump, pool heater, hot tub, outdoor kitchen, landscape lighting, and irrigation system can add significant electrical load. Combined with a large home's baseline demand, these additions can justify 400-amp service.
Properties with guest houses or accessory dwelling units. If you have a guest house, in-law suite, or rental unit on your property that requires its own electrical service, 400-amp service at the main meter may be the most practical solution.
A 400-amp service requires a larger meter base, larger service entrance conductors, and coordination with the utility company to ensure their transformer and service drop can support the increased capacity. The installation is more complex and more expensive than a standard 200-amp upgrade, so it is important to confirm that 400 amps is genuinely necessary before committing to the investment.
How We Determine What You Need
The proper way to determine what amp service your home needs is through a formal load calculation. This is not guesswork. It is a systematic process defined by the NEC (Article 220) that accounts for every electrical load in your home.
The calculation includes the general lighting and receptacle load based on your home's square footage, the nameplate ratings of all fixed appliances, the largest motor load with a 25% adder, and demand factors that account for the fact that not everything runs at the same time. The result is a calculated demand in amps that tells us the minimum service size your home requires.
Beyond the calculated minimum, we also consider your anticipated future needs. If you plan to add an EV charger in the next few years, or if you are considering converting from gas to electric appliances, we factor those future loads into the recommendation so you do not need another upgrade later.
For most homes in the Aiken area, the load calculation confirms that 200-amp service is the right choice. It provides enough capacity for current needs with comfortable headroom for additions. For smaller homes with gas appliances, 100 amps may be confirmed as adequate. For large, all-electric homes with heavy accessory loads, 400 amps may be warranted.
Cost Differences
The cost difference between panel sizes is meaningful but may be less than you expect. Upgrading from 100-amp to 200-amp service costs more than simply replacing a panel at the same amperage because it typically requires upgrading the service entrance conductors, the meter base, and sometimes the utility company's service drop. However, the incremental cost of the larger panel and breakers themselves is relatively modest.
Going from 200-amp to 400-amp service is a more significant investment because it requires a 400-amp meter base, dual 200-amp panels, larger service entrance equipment, and utility coordination that may include a transformer upgrade. This is why we only recommend 400-amp service when the load calculation genuinely warrants it.
The best approach is to get a proper load calculation and a detailed quote that breaks down the costs for each option. This allows you to make an informed decision based on your actual needs and budget, rather than guessing or defaulting to the most or least expensive option.
Next Steps
Unity Power & Light helps homeowners in Aiken, SC determine the right panel size for their homes. We perform load calculations, assess your current and future electrical needs, and provide clear, flat-rate quotes for panel upgrades at every service level.
Whether you are upgrading from an old 100-amp panel to 200 amps, or you need to evaluate whether your property requires 400-amp service, we give you straightforward recommendations based on the numbers, not upselling. Contact us to schedule an assessment.