40 A charger on a NEMA 14-50 outlet (50 A breaker): parts list
Short answer: A plug-in charger drawing 40 A needs a 50 A circuit and a NEMA 14-50 or 6-50 outlet. Mike Holt's Article 625 guide pairs that 50 A breaker with 8 AWG copper rated 75°C, or 6 AWG if you use NM cable.
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| Part | What to use |
|---|---|
| Circuit breaker | 50 A two-pole (40 A × 125% = 50 A) |
| Wire | 8 AWG copper THHN/THWN at 75°C (50 A), or 6 AWG NM-B cable (55 A at 60°C) |
| Outlet | NEMA 14-50R or 6-50R; ChargePoint asks for the outlet 20–26 in. off the floor because its input cord is 12 in. |
| Charger | Plug-in unit set to 40 A (ChargePoint Home Flex: 50 A circuit → 40 A max) |
| Protection | The 2023 NEC requires GFCI on this garage outlet; ChargePoint recommends hardwiring where GFCI is required, to avoid nuisance trips |
Power you get
| At 240 V | 9.6 kW |
|---|---|
| At 208 V | 8.3 kW |
| Added in 8 hours | 76.8 kWh |
Things to check
- ChargePoint says to use a new, dedicated, non-GFCI two-pole breaker. That conflicts with the 2023 NEC garage GFCI rule, which is why ChargePoint suggests hardwiring instead.
- 40 A at 240 V is 9.6 kW. On 208 V it is about 8.3 kW.
- Over eight hours, 9.6 kW adds about 76.8 kWh.
Ground-wire size is not listed; your electrician sizes it under NEC Table 250.122. Have a licensed electrician do the work and pull the permit. All four setups.
Sources: Mike Holt – Article 625 Electric Vehicle Power Transfer System (PDF); NEC Table 310.16 ampacities (nectables.com restatement); ChargePoint – Home Flex electrician installation tips; ChargePoint – Home Flex: wire the circuit; City of Saint Paul – 2023 NEC garage electrical checklist (PDF) (accessed 2026-10-25).