EV Charger Wiring: Complete Wiring Guide
Bill of materials
Level 2 EV chargers run for hours at a time, making them continuous loads per NEC 625.41. The circuit must be sized at 125% of charger amperage: a 48A charger requires a 60A circuit, not 50A.
EV charger circuits are continuous loads per NEC 625.41. The circuit must be rated at 125% of the charger nameplate current. GFCI protection is required per 625.54 for all EV charging equipment.
32A charger (40A breaker)
| Component | Specification | NEC basis |
|---|---|---|
| Wire (copper) | 8 AWG THHN | Table 310.16, 110.14(C) |
| Wire (aluminum alt.) | 6 AWG THHN | Table 310.16, 110.14(C) |
| Breaker | 40A double-pole | 240.4 |
| Voltage | 240V single-phase | |
| Conduit (EMT) | 3/4" EMT | Chapter 9 Table 4 |
| GFCI | Required (GFCI breaker or device) | 625.54 |
| Max distance (3% VD) | 144 ft at 240V copper | 210.19(A) Note 4 |
48A charger (60A breaker)
| Component | Specification | NEC basis |
|---|---|---|
| Wire (copper) | 6 AWG THHN | Table 310.16, 110.14(C) |
| Wire (aluminum alt.) | 4 AWG THHN | Table 310.16, 110.14(C) |
| Breaker | 60A double-pole | 240.4 |
| Voltage | 240V single-phase | |
| Conduit (EMT) | 3/4" EMT | Chapter 9 Table 4 |
| GFCI | Required (GFCI breaker or device) | 625.54 |
| Max distance (3% VD) | 153 ft at 240V copper | 210.19(A) Note 4 |
Installation notes
This project requires GFCI protection per NEC 625.54. The simplest approach is a GFCI breaker at the panel, which protects the entire circuit. For 240V circuits, use a 2-pole GFCI breaker sized to match the circuit. GFCI breakers cost $40-80 depending on amperage.
For the wire run, you have two options: NM-B cable (Romex) for interior runs through framing, or individual THHN conductors in conduit for exposed runs, outdoor installations, or runs through unfinished spaces. NM-B is faster to install but cannot be used outdoors or in conduit. For conduit, use EMT (metallic) or PVC Schedule 40.
Run length matters: every foot of wire adds voltage drop, reducing power to your equipment. The table below shows the exact voltage drop at common distances. If your run exceeds the 3% threshold, upsize one gauge.
Voltage drop by distance
Percentage voltage drop at common run lengths. NEC recommends 3% maximum for branch circuits and 5% for combined feeder plus branch.
| Distance | 8 AWG Co | 6 AWG Al | 6 AWG Co |
|---|---|---|---|
| 25 ft | 0.5% | 0.5% | 0.3% |
| 50 ft | 1.0% | 1.1% | 0.7% |
| 75 ft | 1.6% | 1.6% | 1.0% |
| 100 ft | 2.1% | 2.1% | 1.3% |
| 150 ft | 3.1% | 3.2% | 2.0% |
| 200 ft | 4.2% | 4.3% | 2.6% |
Common products for 8 AWG Copper circuits
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Related wire data
Detailed ampacity: 8 AWG copper, 6 AWG aluminum. Wire size lookup: 40A circuit. Calculators: voltage drop · panel load calculator.
How NEC edition affects this project
Not every state uses the same NEC edition. The table below shows how requirements for this project differ depending on which edition your state has adopted. Find your state's edition here.
| Requirement | NEC 2023 | Earlier editions |
|---|---|---|
| Garage EVSE requirement | New attached garages must have EV-ready outlet or EVSE per 625.40 | No requirement for EV infrastructure in new construction |
| Load management | Multiple EVSE permitted on single feeder with load management per 625.42 | Each EVSE must be individually sized at full continuous load |
| GFCI | GFCI required for outlets up to 50A in garages | GFCI required for 125V 15/20A in garages only |
Currently, 17 states enforce NEC 2023, 21 use NEC 2020, 7 use NEC 2017, and 2 are still on NEC 2008. Three states (Arizona, Mississippi, Missouri) defer to local jurisdictions. Find your state to see which specific rules apply to your location.
Inspection preparation
Before your EV charger inspection, verify these frequently-checked items:
| Check | NEC Ref | Common Fail |
|---|---|---|
| Breaker sized for continuous load (125%) | NEC 625.41 | EVSE continuous load not factored (e.g., 48A charger needs 60A breaker) |
| Wire gauge matches breaker and run length | NEC 310.16 | Undersized conductors for circuit amperage or distance |
| EVSE listed and labeled | NEC 625.10 | Unlisted or improperly rated charging equipment |
| Outdoor installation: weatherproof enclosure | NEC 625.10 | Indoor-rated EVSE installed outdoors |
| Proper conduit/cable for location | NEC 300.5/334 | NM cable used outdoors or underground without proper protection |
See the full inspection checklist tool for all 9 items with progress tracking.
Frequently asked questions
What wire size do I need for ev charger wiring?
Use 8 AWG copper or 6 AWG aluminum on a 40A breaker at 240V. This is based on NEC 2023 Table 310.16 ampacity with 110.14(C) termination limits and 125% continuous load sizing per 210.19(A)(1).
Does ev charger wiring require GFCI?
Yes. GFCI protection is required per NEC 625.54.
NEC 2023 references verified April 2026