🔎 How to find your panel amperage:
Look at the main breaker (usually at the top or bottom of the panel). The number printed on the handle (e.g., 100, 200) is your amperage. If you see a fuse box or can’t locate it, click here for more help.
- Complete the form to get personalized advice.
⚡ This tool provides an estimate based on NEC 220.82 (optional method). Always consult a licensed electrician for a final assessment.
What is the 80% rule?
NEC requires that continuous loads (like EV charging) do not exceed 80% of the circuit's rated capacity. For example, a 40A breaker can safely handle 32A continuously.
What is a load calculation?
A load calculation sums all the electrical demands in your home (lighting, appliances, HVAC) to determine total amperage required. The NEC 220.82 optional method is the standard for residential load calculations.
What if my panel is “tight”?
“Tight” means you have limited spare capacity. You may be able to install a smaller charger, use load management, or add tandem breakers to free up space.
What is load management?
Load management devices (like the Emporia Load Management or Wallbox Power Boost) automatically adjust EV charging to avoid overloading your panel. They cost $400–$800 and can often avoid a $2,000+ panel upgrade.
What is a tandem breaker?
A tandem breaker fits two circuits in one slot, freeing space in your panel. This is a low-cost solution if your panel has limited physical slots but sufficient amperage.
This tool is for educational and estimation purposes only. It is not a substitute for a professional electrical inspection. Always follow local building codes and consult a licensed electrician.