Residential EV Charger Load Planner

Check whether your home service panel can host a Level 2 charger without tripping breakers. Enter the panel rating, continuous loads already present, and the charger’s continuous current to see safe headroom, whether a management system is required, and the projected nightly energy cost.

Main breaker rating (e.g., 100 A, 150 A, 200 A).
Sum of other continuous loads (HVAC, range, etc.) at their demand level.
Breaker rating × 0.8 for most Level 2 chargers (e.g., 50 A breaker → 40 A continuous).
Optional. Default 80% (NEC continuous-load rule).
Optional. Default 8 hours per session.
Optional. Default $0.14 per kWh.

This planner provides a simplified load calculation and does not replace a licensed electrician’s service load analysis or local code requirements.

Examples

  • 100 A panel, 52 A existing load, 40 A charger, default utilisation ⇒ Safe capacity 80.0 A, headroom 28.0 A, charger exceeds headroom by 12.0 A so load management or service upgrade required. Nightly energy 7.68 kWh costing $1.23.
  • 200 A panel, 90 A load, 32 A charger, utilisation 70%, 10 h charge, $0.20/kWh ⇒ Safe capacity 140.0 A, headroom 50.0 A, charger fits with 18.0 A spare. Energy 7.68 kWh costing $1.54.

FAQ

What if my panel has demand management already installed?

Set the allowed utilisation above 80% (e.g., 90%) only if the system actively sheds load. The calculator adjusts headroom instantly.

How do I estimate existing load?

Add up continuous appliances such as HVAC, water heaters, and ranges using their continuous draw, not breaker size. Your electrician can perform a load calculation to refine the value.

Can I model Level 1 charging?

Yes. Enter the Level 1 current (typically 12 A) and adjust charge hours to 12–14 to see energy demand and cost.

Additional Information

  • The NEC continuous-load rule limits sustained load to 80% of breaker rating unless demand factors justify less.
  • Continuous EV charging current equals 125% of the nameplate amp draw when sizing breakers; most 40 A chargers require 50 A breakers.
  • Energy use assumes 240 V single-phase supply; adjust hours to reflect time-of-use windows.

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