Electrical Panel Upgrade Guide — 100A to 200A and Beyond
The panel is the one upgrade that enables everything else — EV charger, heat pump, induction range, finished basement. Here's when to upgrade, to what, and what the work involves.
Quick answer: Panel upgrade costs: 100A $800–1,500 · 200A $1,500–3,000 · 400A $2,500–4,500. Sub panel +40% of base; rewiring +60%. Upgrade triggers: EV charger on a full panel, heat pump, frequent breaker trips, Federal Pacific/Zinsco panels (fire hazard — replace regardless). 200A is the modern standard.
The trigger list — upgrade when you…
- Add an EV charger and the panel is full or 100A
- Install a heat pump (adds 20–40A of load)
- Trip breakers regularly or dim lights when appliances start
- Own a Federal Pacific, Zinsco or fuse box (documented fire hazards)
- Renovate/add square footage (code requires capacity review)
What amperage you actually need
100A: gas appliances, no EV, no AC-heavy home — legacy adequate. 200A: the modern standard — EV + heat pump + electric range + AC all coexist. 400A: big all-electric homes, shops with welders, or two EVs fast-charging. Going 200A today costs $1,500–3,000; retrofitting later mid-project costs more, so size for the electrification you'll do in 10 years.
Sub panel vs full upgrade
A sub panel ($600–1,200) splits circuits into a second box — right when the main panel is full but service amperage is adequate (e.g., garage shop circuits). Full upgrade replaces the box and raises service amperage — required when total load exceeds the service. An electrician's load calculation decides which; it's 15 minutes and should be free with a quote.
What the work involves
Power off 4–6 hours. Utility disconnect/reconnect (the utility's schedule, often next-day). New box, breakers, grounding, bonding. Permit + inspection always. Old cloth or aluminum branch wiring found during the work: budget the +60% rewire line. One day of work, one inspection, done for 30+ years.