A heat pump quote comes back with a line item you didn’t expect: “service upgrade to 200A.” Or the EV dealer says you’ll need a panel upgrade for the charger. Before you add $3,200–$5,800 to the project, it’s worth knowing when 100 amps really isn’t enough.
The short answer: it depends on your actual load
New York’s own energy agency and independent researchers don’t fully agree, which tells you the answer is house-specific:
- NYSERDA: homes with 100–150 amps that add appliances, EV chargers or all-electric heat pumps could exceed their capacity, and a 200-amp panel is typically sufficient for an all-electric home.
- NYS Clean Heat Connect rates the likelihood: homes under 100 amps, or built before 1965, likely need more amperage; 100A, 150A and 200A homes possibly do; above 200A, unlikely. A 100A panel with no open breaker spaces is a case where an upgrade is best practice.
- The counterpoint (New Buildings Institute): many homes with 100- or 150-amp panels can go all-electric without an upgrade, especially with careful equipment choices.
The tiebreaker is a load calculation done by a licensed electrician, based on what you actually run, not on the panel’s label.
What typically pushes a Long Island house past 100 amps
| Load | Why it matters |
|---|---|
| Central air or a ducted heat pump | A 3-ton system draws roughly 30–40 amps, and runs for long stretches |
| Level 2 EV charger | A continuous 40–60 amp load, often overnight |
| Electric range, dryer, water heater | Big 240V loads that overlap with the above |
| Pool pump and heater, hot tub | Long run times plus high draw |
| Detached garage or workshop sub-panel | Adds connected load and often a long feeder |
| No open breaker spaces | Even if amps allow it, there’s nowhere to add the circuit |
Long Island’s housing makes this common: Levittown-era capes and ranches across Hempstead and the 1960s–70s colonials and high-ranches of Smithtown were built for far less power, and many still run on their first upgrade to 100 amps.
Alternatives to a full service upgrade
Ask your electrician whether any of these fit before committing to 200 amps:
- EV load management. A load-management device (or a charger with built-in power sharing) throttles charging when the house is busy, so the charger shares capacity instead of requiring more. See EV charger costs.
- Right-size the heat pump and choose efficient equipment, with a proper heating and cooling load calculation instead of sizing up “to be safe.”
- Keep a gas range or dryer for now and electrify those later, if you’re not going fully electric yet.
- A sub-panel or tandem breakers where the panel allows it, to solve a space problem without adding amps.
When to just do the upgrade
- The load calculation says you’re over, even with management
- You have a Federal Pacific, Zinsco or fuse panel (replace it anyway)
- The panel is full and old, or the meter pan and mast are failing
- You’re planning the heat pump, an EV and maybe solar in the next few years. One upgrade beats three partial fixes
If you go ahead, here’s the whole process: upgrading to 200 amps on Long Island, and the full price breakdown: panel upgrade cost.
Questions to ask for your quote
- Did you do a load calculation, and can I see it?
- Would load management avoid the upgrade?
- How many open breaker spaces do I have?
- If I do upgrade, are the permit, agency inspection and PSEG LI scheduling included?
Need it done? See panel & service upgrades on Long Island. Local rules: Hempstead, Smithtown.