The 32A derate rule
National Electrical Code 625 requires continuous loads (anything pulling more than 3 hours) to be sized at 125% of the breaker. A NEMA 14-50 outlet is typically on a 40A or 50A breaker:
- 50A breaker → 40A breaker × 80% = 40A max continuous. Most portables cap at 32A regardless.
- 40A breaker → 32A max continuous. This is what most portables actually use.
Either way, you'll get 32A continuous from a NEMA 14-50 — not the 50A the outlet's name suggests.
When NEMA 14-50 is the right choice
- You have a Tesla and want to use the Mobile Connector instead of a Wall Connector
- You travel between two homes and want to take the charger with you
- You're renting and the landlord allows an outlet but not a hardwired install
- Your car caps at 32A onboard (Chevy Bolt, etc.) — the 14-50 captures the full rate
- You're future-proofing a garage for a future-buyer who'll bring their own portable
When hardwired is better
- You have a Tesla and want the manufacturer warranty (Tesla requires hardwired)
- Your car can use 48A (most Teslas, Rivian, Ioniq 5/EV6, BMW i4) — hardwired gets you the full rate
- Permanent home, plan to live there long-term
- You don't need to take the charger anywhere else
The decision rule: NEMA 14-50 if you want portability or your car caps at 32A. Hardwired everything else. Network installers will recommend the right one without upsell — both are roughly equivalent profitability for them.