Installing a Level 2 EV Charger (48A)
Install a 48A Level 2 EV charger in a residential garage — circuit sizing, panel capacity check, and NEC 625 compliance.
Scenario Overview
Install a 48A hardwired Level 2 EVSE (Tesla Wall Connector) in an attached garage on an existing 200A residential service. Verify panel capacity and size the circuit.
Given Information
- •Existing 200A, 120/240V residential service
- •EVSE: 48A, 240V hardwired (Tesla Wall Connector)
- •Cable run: 35 feet from main panel to garage wall
- •Panel currently at approximately 145A calculated demand
- •Conduit: EMT surface-mounted in garage
Calculation Steps
Calculate Circuit Requirements
48A EVSE = continuous load (operates > 3 hours).
NEC 625: OCPD = 48A × 1.25 = 60A.
Need a 60A breaker and conductors rated for 60A.
Result: 60A circuit required
Size Conductors
60A at 75°C: NEC Table 310.16 — 6 AWG copper = 65A. Adequate.
For EMT in garage: use 6 AWG THHN copper (2 hots + 1 ground, no neutral for 240V-only EVSE).
Ground wire: NEC 250.122 — 60A circuit = 10 AWG copper EGC.
Result: 6 AWG copper THHN + 10 AWG EGC
Check Voltage Drop
35 ft run, 48A (actual load), 6 AWG copper (R = 0.491 Ω/1000ft).
VD = 2 × 35 × 48 × 0.491 / 1000 = 1.65V.
VD% = 1.65 / 240 = 0.69% — excellent.
Result: 0.69% voltage drop ✓
Verify Panel Capacity (120% Rule)
Existing demand: 145A. Adding 60A EV = 205A total breaker.
NEC 705 120% rule doesn't apply here (that's for solar backfeed).
For standard loads: verify total demand doesn't exceed 200A service.
New total calculated demand: 145A + (48A × 240V / 240V) = 193A.
Within 200A service capacity.
Result: 193A total demand — within 200A service ✓
GFCI Protection (NEC 625.54)
NEC 625.54 requires GFCI protection for all EV charging equipment.
NEC 2023: GFCI now applies to 250V circuits including 240V EVSE.
Options: GFCI breaker (60A dual-function) or EVSE with built-in GFCI.
Tesla Wall Connector has built-in GFCI — compliant without GFCI breaker.
Result: Built-in GFCI satisfies NEC 625.54
Conduit and Installation
Conduit: 2× 6 AWG THHN + 1× 10 AWG bare copper in EMT.
NEC Ch9: 6 AWG THHN area = 0.0507 in², 10 AWG bare = 0.0116 in².
Total: 2(0.0507) + 0.0116 = 0.113 in². 40% of ½" EMT (0.304 in²) = 0.122 in².
½" EMT is adequate.
Result: ½" EMT conduit
Final Answer
Install the 48A Tesla Wall Connector on a dedicated 60A, 240V circuit using 6 AWG copper THHN in ½" EMT, with a 10 AWG copper EGC. 60A 2-pole breaker in the main panel. Panel capacity verified at 193A on 200A service.
Key Takeaways
- •EV charging is always a continuous load — apply 125% to EVSE rated current
- •Many EVSEs have built-in GFCI, eliminating the need for expensive GFCI breakers
- •Always verify panel capacity before adding a 40-60A EV charger circuit
- •For homes near panel capacity, consider EV load management (NEC 625.42) instead of service upgrade
Calculators Used
NEC References
- NEC 625 — Electric Vehicle Power Transfer System
- NEC 625.54 — GFCI Protection
- NEC 210.20(A) — Continuous Load Factor