Quick answer
Run the load calculation before you spend anything — amps are capacity, not performance. A 100-amp service carries many homes fine until electrification stacks up: a heat pump, EV charger, induction range, and heat pump water heater together usually justify 200 amps ($8,000–$16,000 installed in the Puget Sound). But a load calculation plus load-management controls or a smart panel keeps plenty of 100-amp homes electrifying without the service upgrade.
- Amperage is how much the home can draw at once — 100 amps was the postwar standard, 200 amps is today's, and neither is 'better' unless your actual load needs it.
- The NEC load calculation decides it: square footage, fixed appliances, and the new electric loads you're planning, not the sticker on the panel door.
- A full 100A→200A service upgrade — new panel, meter base, mast, and utility coordination — typically runs $8,000–$16,000 installed here.
- Load-management devices and smart panels can shed or schedule big loads so a 100-amp service never exceeds its limit — often the cheaper path to a heat pump plus EV.
- For income-eligible households, WA HEAR can put up to $4,000 toward panel work when it enables electrification.
What does each option cost installed in the Seattle area?
The honest comparison is a service upgrade versus a smaller intervention that makes 100 amps enough. Which one your home needs is exactly what a load calculation tells you — done before equipment is ordered, not after.
| Option | Typical installed range | What that covers |
|---|---|---|
| Service upgrade (100A → 200A) | $8,000–$16,000 | New 200A panel, meter base and mast work, utility disconnect/reconnect coordination, permit and inspection — the full-capacity path when the load math genuinely exceeds 100 amps. |
| Panel replacement only (200A, same service) | $4,000–$9,000 | When the service conductors already support it and the panel itself is the limit (full slots, aging or recalled equipment), a like-for-like replacement restores capacity and safety without touching the service. |
| Load management or smart panel on 100A | Varies by home | A load-management controller for the EV charger or a smart panel that schedules big loads — often what lets a 100-amp home add a heat pump and Level 2 charging without a service upgrade. |
| Add a sub-panel | $1,500–$3,500 | Solves a different problem: no open breaker slots. It adds circuits, not capacity — the service amperage stays what it was. |
What changes the price
- The load calculation result — the one number that decides the question; everything else is preference.
- Meter and mast condition: if the service entrance needs rebuilding anyway, the upgrade increment shrinks.
- Permit authority: Seattle (SDCI), Bellevue, Everett and several cities self-inspect; Tacoma Power inspects its territory; state L&I covers the rest.
- Utility coordination: the disconnect/reconnect window is scheduled with your utility and can drive timeline more than the electrical work itself.
- What's coming next: pricing the panel for the EV charger you'll add in two years costs less than doing panel work twice.
Ranges are representative Seattle / Puget Sound installed prices, not a quote — your home's specifics set the real number. Eco gives you an upfront price before any work begins.
How do they work differently?
What 200-amp service changes
The service conductors, meter base, and main breaker are sized for double the simultaneous draw, and the new panel typically adds far more breaker spaces. Every future project — ADU, hot tub, second EV — lands in a panel with room to spare. The house's wiring beyond the panel is unchanged; capacity, not condition, is what you bought.
How a 100-amp home electrifies without the upgrade
Load management works because peak loads rarely coincide: an EV charger that pauses while the dryer and heat pump run, or a smart panel that schedules circuits, keeps total draw inside 100 amps. The NEC explicitly allows these managed designs — the equipment documents its limit, and the inspector signs off on the math.
Pros and cons, honestly
Upgrade to 200-amp service
Pros
- Permanent headroom for full electrification and whatever comes after
- New panel hardware retires aging or recalled equipment at the same time
- No load juggling — every appliance can run at once
Cons
- The most expensive path — $8,000–$16,000 installed
- Utility coordination and permit timelines add lead time
- Overkill if the load calculation says 100 amps still fits your plans
Stay on 100 amps with load management
Pros
- Thousands less upfront — often the difference that funds the heat pump itself
- Modern controls make the limit invisible in daily life
- Income-eligible HEAR support can still apply to enabling panel work
Cons
- Big simultaneous loads are scheduled, not unlimited
- A future ADU or major addition may force the service upgrade anyway
- Old panels at 100A may still need replacement for condition reasons
Which one should you choose?
When the 200-amp upgrade wins
Your load calculation comes back over 100 amps with the projects you actually plan; the panel is a recalled or slot-starved unit that needs replacing anyway; or you're electrifying everything — heat pump, water heater, range, dryer, and two-car EV charging — and want the house permanently ahead of demand.
When staying on 100 amps wins
The math fits with managed charging, the panel itself is in sound condition, and the money saved moves the heat pump or water heater project forward now. A managed 100-amp home electrifies just as completely — it simply schedules its biggest draws.
Also consider: the sub-panel
If the real problem is 'no open slots' rather than 'not enough amps,' a $1,500–$3,500 sub-panel adds circuit space without touching the service — a common miss that turns a one-day job into an unnecessary five-figure one.
Ready to compare for your home?
Get honest numbers for both options side by side — an upfront range, the considerations, and the rebates you qualify for, before any work begins.
Continue exploring
- Book: Panel upgrades →
- Book: EV charger installation →
- Book: Whole-home electrification →
- Compare: Panel Repair vs Replacement: Which Does Your Breaker Box Actually Need? →
- Compare: Level 2 vs Level 1 EV Charging: What Does Your Commute Actually Need? →
- Compare: Smart Home Energy Management vs the Traditional Home: What Actually Changes →
- Panel upgrade decision guide →
- SPAN smart panel vs traditional panel →
- How much does an electrical panel cost? →
- Washington rebates & incentives →
- All electrical comparisons →
Common questions
How do I find out if my home has 100-amp or 200-amp service?
The main breaker at the top of your panel is labeled with its rating — 100, 125, 150, or 200. That's the service size (the number on individual branch breakers is per-circuit). If the panel is a fuse box, it predates both standards and is worth an assessment on its own.
Can I add an EV charger and a heat pump on 100-amp service?
Frequently yes. A load calculation establishes the headroom, and a load-management device or smart panel keeps the charger inside it. Whether that's smarter than upgrading depends on the rest of your electrification plans — which is exactly the comparison above.
Where do these price ranges come from?
They're Eco's current installed ranges for Puget Sound homes — the same client-verified figures on our electrical panel cost guide — covering equipment, labor, permits, and utility coordination. Your written quote is exact; these ranges exist so you can plan before anyone visits.
Does a bigger panel lower my electric bill?
No — amperage is capacity, not efficiency. The bill changes come from the equipment the capacity enables, like a heat pump replacing resistance heat. The panel is infrastructure: it makes the efficient loads possible and safe.
Last updated: 2026-07-12