What Electrical Service Size Actually Means
Your home's electrical service is the main supply from the utility company to your panel. The amperage rating—100A, 200A, or occasionally 150A—tells you the maximum current your entire house can pull at once before the main breaker trips.
Think of it like a water main. A larger pipe delivers more volume. A 100-amp service can handle roughly 24,000 watts at 240 volts. A 200-amp service doubles that to around 48,000 watts. That difference matters when you're running central air, an electric range, a heat pump, an EV charger, and a pool pump simultaneously.
Most homes built before the 1980s have 100-amp service. Anything built in the last twenty years typically has 200-amp. If you're planning major renovations—adding square footage, installing a hot tub, or switching from gas to electric appliances—your existing service may not keep up.
When 100-Amp Service Is Enough
A 100-amp panel works fine for smaller homes with modest electrical loads. If you have gas heat, a gas water heater, a gas range, and no plans for high-draw additions, 100 amps may cover you for years.
Typical 100-amp households run a central AC unit (15-20 amps), a gas furnace blower (8-12 amps), a refrigerator, lights, TVs, and smaller appliances without issue. You're not loading every circuit at peak simultaneously—diversity factor keeps actual demand well below the service rating most of the time.
Problems surface when you add electric baseboards, a second AC compressor, or a Level 2 EV charger pulling 40-50 amps. Suddenly you're close to or over capacity during peak evening hours. Nuisance main-breaker trips are the warning sign. If that's happening, you need an upgrade or load management devices—and neither is a DIY project.
Why 200-Amp Service Is the Modern Standard
Code doesn't mandate 200-amp service for every home, but builders install it by default because it future-proofs the house. Electric vehicles, induction cooktops, heat-pump HVAC, tankless electric water heaters, home offices with server racks—none of these were common thirty years ago.
A 200-amp panel gives you headroom. You can add a 60-amp subpanel for a detached garage workshop. You can install a NEMA 14-50 outlet for an EV without derating other circuits. You won't hit capacity limits during a Florida summer when two AC zones, the pool pump, the dryer, and the range all run at once.
Resale value benefits, too. Home inspectors and buyers flag 100-amp service as a potential upgrade cost. Listing a home with 200-amp service removes that objection and signals the electrical system can handle modern demands.
Cost and Scope of a Service Upgrade
Upgrading from 100-amp to 200-amp service isn't just swapping the panel. The utility company may need to replace the transformer or service drop. You'll need a new meter base, a new service mast or underground lateral, heavier service conductors (often aluminum for cost, sometimes copper), and a larger main panel with more circuit positions.
Permit and inspection fees add to the bill. The utility coordination alone can take weeks. Total cost in South Florida typically ranges from a few thousand dollars into five figures, depending on service entrance location, underground vs overhead, distance from the street, and how much interior rewiring you bundle into the project.
Get an up-front quote before any hammers swing. A licensed electrician will calculate your load, check utility requirements, pull permits, and coordinate the meter disconnect. Trying to DIY any portion of a service upgrade is illegal and dangerous—you're working on the service conductors that feed your entire home.
For a full breakdown of our electrical services and what a panel upgrade entails, visit our services page.
How to Know If You Need an Upgrade Now
Check your main panel. If it's a Federal Pacific, Zinsco, or another recalled brand, replace it regardless of amperage—those panels have documented failure rates. If you see rust, burn marks, a warm panel cover, or a humming sound, that's an immediate safety issue.
Beyond that, add up your planned loads. A Level 2 EV charger is 40-50 amps. A central AC is 15-25 amps per zone. An electric range is 40-50 amps. A heat-pump water heater is 15-30 amps. If the total approaches or exceeds 80% of your 100-amp service rating, you're in upgrade territory.
Flickering lights when the AC starts, breakers that trip on hot afternoons, or the need to shut off one appliance to run another—all signs your service is maxed. Don't ignore them. Chronic overloads heat up connections, degrade insulation, and create fire risk over time.
A load calculation by a licensed electrician takes the guesswork out. They'll measure your actual usage, account for future additions, and tell you whether you need 200 amps or if load management and a subpanel can buy you time.
What Happens During the Upgrade
First, the utility company disconnects your service at the meter. Your house goes dark. The electrician removes the old meter base and panel, installs the new service mast or lateral, pulls larger conductors, mounts the 200-amp panel, lands all your existing branch circuits, and reconnects grounds and neutrals per NEC requirements.
Grounding and bonding are critical. The main panel is the only point where neutral and ground bond together. Subpanels downstream must keep them separate. Miss that detail and you create shock hazards and code violations.
After rough-in, the utility sets a new meter and reconnects the service drop. The inspector checks torque on lugs, wire sizing, panel fill, AFCI/GFCI protection on required circuits, and grounding electrode connections. Once you pass, power comes back on—often the same day if everything goes smoothly.
Good electricians protect your belongings, label every circuit clearly, test every breaker, and clean up completely. If you're also upgrading to AFCI breakers on bedroom circuits or adding whole-house surge protection, they'll integrate that work seamlessly.
Making the Right Choice for Your Home
If your home is small, all-gas, and you have no plans for EVs or major additions, 100-amp service may last indefinitely. If you're renovating, adding square footage, electrifying appliances, or installing renewable energy, 200-amp service is the safer bet.
Don't base the decision on initial cost alone. A service upgrade is a once-in-a-lifetime project for most homeowners. Undersizing it to save money now means doing it twice later—at greater total expense and inconvenience.
Work with a licensed, insured electrician who will pull permits, coordinate the utility, and guarantee code-compliant work. Check our blog for more guidance on panel upgrades, circuit additions, and electrical safety. If you need help sizing your service or have questions about an existing system, reach out for a professional assessment.