Do You Need a 200-Amp Service Upgrade? An Honest Assessment

What service size actually is

Your "service" is the maximum power the utility connection, meter equipment, and main panel can deliver at once — the width of your house's electrical pipe. 100 amps was the postwar standard and still serves millions of homes fine; 200 amps is today's default for new construction. The number that matters isn't the label, though — it's whether your actual simultaneous demand fits inside it.

The honest capacity math

Here's what surprises people: 100 amps is a lot. At 240 volts that's 24,000 watts flowing at once. A gas-heat, gas-range house running lights, fridge, TVs, laundry, and a window AC might peak at a third of that. The NEC's load calculation (Article 220) exists because appliances don't all run at once — and when an electrician runs that calculation for your house, you get a real number instead of a salesman's feeling.

The loads that change the math are the big electrification items:

• EV charging — a 40–48A Level 2 charger is the single biggest habit-changer; it's like adding a second central AC that runs all night
• Heat pump / electric heat — heating with electrons is the largest load most houses ever add
• Induction/electric range, electric dryer, electric water heater — each modest alone; they stack
• Hot tub, sauna, welder, serious shop tools

A 100A house adding an EV and a heat pump has genuinely outgrown its pipe. A 100A house adding LED bulbs and a smart thermostat has not.

Signs you're actually at the limit

• The main breaker (not branch breakers) trips when big loads coincide
• Whole-house dimming when the dryer or AC starts — though loose connections cause this too, and they're urgent where capacity is merely inconvenient
• The load calculation says demand exceeds ~80% of service size
• No panel spaces left plus new circuits needed (sometimes that's a subpanel problem, not a service problem — cheaper)

The alternatives your quote may not mention

The electrification era produced clever middle paths:

• Load management devices — an EV charger that pauses while the dryer runs, or a smart splitter sharing one circuit between dryer and charger, can fit an EV into a 100A house legally and happily. (Code explicitly supports this now.)
• Right-sized EV charging — most commuters are fully recharged overnight at 16–24 amps; the 48A charger is a want, not a need.
• A subpanel solves "out of spaces" without touching the service.

When upgrading is simply right

If the load calc says so; if you're heading toward EV + heat pump anyway; if the panel is an FPE/Zinsco or a corroded relic needing replacement regardless (upgrading while replacing is the two-birds move); or if you're opening walls in a major remodel. The upgrade is disruptive paperwork-heavy work exactly once — doing it during other work is how you get it nearly free of extra hassle.

Get the load calculation first. It's the difference between buying capacity you need and buying a bigger number.