EV Charging Load Calculations
Sizing service and feeders for charging loads.
Load calculations are the heart of every EV charging station permit design. They prove your electrical service can carry the new charging load — and they decide whether you need a service upgrade or can rely on load management.
The building blocks
Continuous load (125%)
EV charging is a continuous load, so under NEC Article 625 the branch circuit and overcurrent protection are sized to at least 125% of the equipment’s rated current.
Article 220 service load
The connected charging load is added to the building’s calculated load under Article 220 to confirm the service and feeders are adequate.
Service vs upgrade
Comparing the calculated load against the service rating tells you whether you need a service/feeder upgrade or a load-management strategy.
Avoiding an upgrade with load management
NEC 625.42 allows an energy/power management system to cap the charging demand so multiple chargers can share existing capacity without exceeding the rating of the main and feeder breakers. This often lets a site add chargers without an expensive service upgrade — and ELDAPRO can document the approach in your drawing general notes.
How ELDAPRO handles load calcs
ELDAPRO runs the load calculations, sizes the service entrance and feeders, and flags when the existing service can’t carry the new charging load — so you can plan an upgrade or load management early. For the full document list, see our EV charging station permit requirements guide.