NEC 625 — EV Charger Sizing and the 125% Continuous-Load Rule
EV chargers are continuous loads under NEC 625.42. The branch circuit must be sized at 125% of the charger nameplate. What this means for breaker, conductor, and load-calc decisions.
NEC 625.42 defines EV charging equipment as a continuous load — current at maximum is expected for 3 hours or more. Under NEC 215.2 and 230.42, continuous loads must be sized at 125% of the connected load when calculating service or feeder ampacity. This is THE most common mistake electricians make on EV charger installs.
What it means in practice:
- A 48 A Tesla Wall Connector (the most common Level 2 EVSE in NJ) needs a 60 A breaker (48 × 1.25 = 60). Conductor sizing follows the breaker — 6 AWG CU minimum, often upsized to 4 AWG for runs over ~50 ft to keep voltage drop under 3%.
- A 40 A charger (e.g. ChargePoint Home Flex on a 40A setting) needs a 50 A breaker (40 × 1.25 = 50). 8 AWG CU is typical.
- A 32 A charger needs a 40 A breaker (32 × 1.25 = 40). 8 AWG CU is typical.
Disconnect requirements per NEC 625.43: EV charging equipment rated greater than 60 A or 150 V to ground must have a service disconnect within sight of the equipment. Most residential 48 A chargers don't trigger this — they're 240 V line-to-line and 120 V line-to-ground, so the threshold is whether the breaker is over 60 A. 60 A is right at the edge, and many AHJs interpret "greater than 60 A" strictly so a 60 A breaker doesn't require a separate disconnect.
GFCI per NEC 625.54: EV charging equipment is required to be GFCI-protected when it's cord-and-plug connected (NEMA 14-50 receptacle installs). HARDWIRED installations don't require GFCI protection — this is the cleanest install and what most NJ contractors prefer.
Load calculation impact: when adding an EV charger to an existing service, the calc must include the charger at 125% in either the Standard or Optional method (NEC 220 Part III or IV). On a 200A service, a 48 A charger adds 11,520 VA × 1.25 = 14,400 VA to the calculation — not always trivial, especially in older homes with electric ranges and dryers. Always run the calc before quoting an install.
The free Malfettone Load Calculator at /tools/load-calculator has EV charger presets at 32 A / 40 A / 48 A with the 125% multiplier already applied — one click adds the charger to the calculation.
This guide is an educational summary written by a licensed NJ master electrician. It is not a substitute for the National Electrical Code or for the judgment of your local AHJ. For real permit work, verify every code interpretation with your authority having jurisdiction and a licensed electrician of record.