EV Charger Branch, Feeder & Service Calculator
Size branch circuits, feeders, and service entrances for EVSE installations under NEC 625 — supporting Level 1, Level 2, and DC Fast charging with demand factor application and multi-unit feeder aggregation.
Overview
EV charging infrastructure is one of the fastest-growing NEC design challenges, and Article 625 introduces continuous-load factors, demand factor options, and load-management system provisions that are easy to misapply. This calculator works through the complete circuit design hierarchy: branch circuit conductor and OCPD sizing for individual EVSE units, feeder aggregation with demand factors for multiple units, and service entrance sizing. It supports Level 1 (120 V), Level 2 (208 V / 240 V single-phase, 208 V / 480 V three-phase), and DC Fast concepts across NEC 2017 and 2020 editions. Conductor material (aluminum or copper) and temperature rating (60°C, 75°C, or 90°C) are selectable. The Trace tab shows step-by-step NEC calculation logic so every result is traceable to a code section. A Challenge mode presents EVSE design problems for self-assessment. NEC Reference panels are provided for Articles 625, 220, and 310. Designed for engineers and contractors sizing charging infrastructure for commercial and industrial occupancies.
App preview
A live look at the app you'll launch — every control on the left drives the visualizations on the right in real time.
Inside the lab
What you'll do
- 01Apply the NEC Article 625 continuous-load factor to EVSE branch circuit sizing
- 02Select conductor size and OCPD rating for Level 1, Level 2, and DC Fast EVSE circuits
- 03Aggregate multiple EVSE loads with demand factors to size a common feeder
- 04Distinguish load-managed EVSE systems and explain how they affect feeder and service sizing
- 05Compare NEC 2017 vs. 2020 Article 625 provisions and identify changes relevant to EVSE design
- 06Trace every sizing step to the applicable NEC section using the Calculation Trace tab
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