Most Bay Area homes built before 1990 run on a 100-amp (or smaller) service that was never designed for an EV charger, a heat pump, and an induction range running at once. The quick way to know if yours is keeping up: look at the main breaker number on your panel, then count what's already pulling power. If you're at 100A and planning to electrify, you'll likely need an upgrade — here's exactly what each service size can handle, what an upgrade costs locally, and how to read your own panel in five minutes.
What Your Service Size Can Actually Run
| Service Size | Typical In | What It Comfortably Handles |
|---|---|---|
| 60A (or fuse box) | Pre-1960 homes | Basic lighting and outlets only — upgrade strongly recommended |
| 100A | 1960s-1980s homes | Standard home; tight once you add EV + heat pump + induction |
| 200A | Modern / renovated homes | Full electrification: EV, heat pump, induction, A/C |
| 400A | Large homes / ADUs | Two EVs, ADU, pool, whole-house electrification |
Important: a 100-amp panel isn't automatically "too small." We run a real load calculation before recommending an upgrade — sometimes smart load management ($1,000–$1,500) does the job for a fraction of a full upgrade. Don't let anyone sell you 200 amps without measuring your actual usage first. We cover this in do you really need a 200-amp panel.
How to Read Your Own Panel in 5 Minutes
- Find the main breaker — the big switch at the top. The number on it (100, 125, 200) is your service size.
- Check the brand. If it says Federal Pacific (FPE), Stab-Lok, or Zinsco, plan to replace it — these are documented fire hazards.
- Look for a fuse box instead of breakers — that means the system is decades out of date.
- Touch nothing that's warm. A warm or buzzing panel is a same-day call, not a someday project.
Warning Signs Worth Acting On
Individually these seem minor. Together they mean your system is running near its limit:
- Breakers trip when two big appliances run at once
- Lights dim when the A/C or microwave kicks on
- Warm outlets or switch plates, or a buzzing panel
- Extension cords have become permanent
- Two-prong (ungrounded) outlets throughout the house
In a Burlingame home we serviced last year, "occasional" breaker trips turned out to be a backstabbed connection arcing inside a wall — a real fire risk caught before it became a real fire. Small symptoms are information.
What Upgrades Cost in the Bay Area (2026)
| Job | Typical Cost |
|---|---|
| 100A → 200A panel upgrade | $2,500 - $4,500 |
| FPE / Zinsco / fuse-box replacement | $2,800 - $5,000 |
| Smart load management (avoid an upgrade) | $1,000 - $1,500 |
| Adding a dedicated circuit | $300 - $800 |
For the full line-item breakdown by amperage, permits, and PG&E coordination, see our 2026 Bay Area panel upgrade cost guide.
Why a Licensed Electrician (and a Permit) Matters
In California, panel and service work must be done by a licensed C-10 contractor and requires a permit with inspection. Unpermitted electrical work can void your homeowner's insurance, create liability when you sell, and — most importantly — put your family at risk. A permit isn't red tape; it's the paper trail that protects your home and your sale.
Not Sure What Your Home Can Handle?
Fox Electric helps homeowners across San Carlos, Redwood City, San Mateo, Belmont, Palo Alto, Menlo Park, and the wider Bay Area figure out what their electrical system can actually support — before they buy an EV, remodel a kitchen, or add an ADU. We measure real load, give upfront pricing, and only recommend an upgrade when you actually need one.
Call us at (650) 550-0719 or request a free quote online. Estimates are always free.
