EV charger load equation
This calculator estimates charger current and total planned feeder load after applying charger quantity and simultaneity.
where:
- Icharger
- Current per charger[A]
- P
- Power per charger[kW]
- V
- Supply voltage[V]
- PF
- Charger power factor
- N
- Number of chargers
- Ks
- Simultaneity factor as a decimal
- Iplanned
- Planned distribution load current[A]
Final EV charging design should also check load management, earthing system, RCD/RCBO type, SPD selection, and local EV charging rules.
How to calculate EV charger load
EV charging load planning starts with power per charger, supply phase, voltage, charger quantity, power factor, and the expected simultaneity or load-management factor. The result estimates current per charger and the planned coincident feeder current.
- Select single-phase or three-phase AC charging.
- Enter rated input power and supply voltage per charger.
- Enter charger quantity and power factor.
- Apply a project-specific simultaneity factor or controlled-load limit.
- Verify feeder, protection, earthing, residual-current protection, and voltage drop.
EV charger load calculation example
Four 11 kW three-phase chargers at 400 V and 0.98 power factor each draw about 16.2 A. With an 80% simultaneity factor, the planned coincident feeder current is approximately 51.8 A.
Icharger = 11,000 / (√3 × 400 × 0.98) = 16.2 A
Iplanned = 16.2 × 4 × 0.80 = 51.8 A
| Input or result | Value |
|---|---|
| Chargers | 4 × 11 kW |
| Supply | 400 V three-phase |
| Power factor | 0.98 |
| Simultaneity | 80% |
| Current per charger | 16.2 A |
| Planned feeder current | 51.8 A |
Installed EV charging power vs. coincident demand
Installed power is the sum of charger nameplate ratings. Coincident demand is the load expected at the same time after load management or diversity. The simultaneity factor should come from the charging strategy, site operating profile, utility limit, or energy-management design rather than a generic assumption.
| Quantity | Meaning |
|---|---|
| Installed power | Maximum combined nameplate charging power |
| Simultaneity | Expected or controlled fraction operating together |
| Planned demand | Feeder load used for preliminary distribution planning |
Protection checks for EV charging circuits
Final EV supply equipment design must follow manufacturer instructions and locally adopted installation rules. Check overcurrent protection, residual-current protection and DC leakage handling, earthing arrangement, surge protection, isolation, cable thermal loading, voltage drop, and load management. DC fast charging needs a more detailed input and power-quality study.
Complete the EV feeder design
Use planned current as an input to cable and breaker checks, then confirm actual charger input current and protective-device requirements from the equipment documentation.
Circuit Breaker Size CalculatorCable Size CalculatorSPD Calculator
Assumptions
- AC chargers
- Balanced three-phase loading when three-phase is selected
- Demand management is represented by simultaneity factor
Important Warnings
- Final EV charging design must check IEC 61851, local code, RCD/RCBO requirements, earthing system, and load management.
- DC fast chargers require a more detailed system study.