EV Charging Outlet Types: A Field Guide

A heavy-duty electrical receptacle mounted on a wall

The outlet decides your charging speed far more than the charger does. Here is what you will encounter, what each delivers, and which adapters are worth owning.

Outlet types and what they deliver
Outlet	Volts	Circuit	Max charging	Miles per hour	Where you find it
NEMA 5-15	120 V	15 A	12 A / 1.4 kW	about 5	Every normal wall outlet
NEMA 5-20	120 V	20 A	16 A / 1.9 kW	about 7	Garages, workshops
NEMA TT-30	120 V	30 A	24 A / 2.9 kW	about 10	RV sites and campgrounds
NEMA 6-20	240 V	20 A	16 A / 3.8 kW	about 13	Workshops
NEMA 10-30	240 V	30 A	24 A / 5.8 kW	about 20	Older dryer outlets, no separate ground
NEMA 14-30	240 V	30 A	24 A / 5.8 kW	about 20	Modern dryer outlets
NEMA 6-50	240 V	50 A	40 A / 9.6 kW	about 34	Welder outlets
NEMA 14-50	240 V	50 A	40 A / 9.6 kW	about 34	Ranges, RV hookups, EV circuits

Maximum charging is 80% of the circuit rating -- the continuous-load rule. Miles per hour assume 3.5 mi/kWh. Always confirm your charger supports the outlet type before adapting to it.

The three worth carrying adapters for

NEMA 14-50. The one that matters. It is the EV-charging standard, it is on every RV hookup, and it gives you 40 amps. Most portables ship with this plug already.
NEMA 5-15. The fallback that works everywhere. Most portables include this adapter.
NEMA TT-30. Only if campgrounds appear on your routes, but then it is genuinely useful -- about 100 miles overnight.

Everything else is situational. Buy an adapter when you know you will meet the outlet, not on the theory that you might.

The one to be careful with: NEMA 10-30

The old three-prong dryer outlet has two hots and a neutral, but no separate ground. Modern practice requires a separate ground for this kind of load, and many chargers will refuse to operate without one -- correctly.

If your charger explicitly supports a 10-30 adapter, follow its manufacturer's instructions. Do not improvise a ground, do not use an adapter that ties neutral to ground, and if in doubt, do not use the outlet.

How to tell what you are looking at

The pin pattern is the identifier. A 5-15 has two flat blades and a round ground. A 14-50 has two angled flat blades, an L-shaped neutral and a round ground -- it is unmistakably large. A 6-50 has two flat blades and a ground with no neutral. TT-30 is round with three angled slots and looks like nothing else.

If you cannot identify it with certainty, photograph it and ask before plugging anything in. A wrong assumption here is not a mild inconvenience.

FAQ

Questions people actually ask

What outlet do I need for a Level 2 EV charger?

Most commonly a NEMA 14-50, a 240-volt 50-amp receptacle that allows 40 amps of continuous charging, or roughly 34 miles of range per hour.

Can I charge my EV from a dryer outlet?

Sometimes. A modern NEMA 14-30 allows 24 amps, about 20 miles per hour. Older NEMA 10-30 outlets have no separate ground and many chargers will refuse them, correctly.

What is a NEMA TT-30 outlet?

The standard 120-volt, 30-amp RV site outlet. With the right adapter it allows about 24 amps of charging, roughly 10 miles of range per hour.

Can I chain two adapters together?

No. Every plug junction is a heat source under a continuous load, and stacking them concentrates the risk where you cannot see it.

Sources

Where these numbers come from

Portable Level 2 EV charger 40A (UL) -- J+ Booster 2 — J+ AmericasPublished adapter range: 5-15, 5-20, 6-15, 6-20, 6-50, 14-50, TT-30.
NEC Article 625: EV charging equipment — WireRefContinuous-load rule behind the maximum charging column.