Technical Reference

NEMA Connector Guide

NEMA WD 6 straight-blade and locking connector specifications, pin configurations, applications, and selection guidance. The authoritative reference for North American power connectors.

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Naming Convention

The NEMA naming convention

NEMA designations follow the format [Series]-[Amperage][P or R]. The physical pin layout is intentionally unique to each voltage/amperage combination — you cannot accidentally plug a 250V cord into a 125V receptacle, which is a key safety feature of the NEMA system.

Series number
Encodes voltage and grounding. Series 1–8 are 125V or 125/250V. Series 5 = 125V grounded (most common). Series 6 = 250V grounded. L-prefix = locking.
Amperage
15, 20, 30, 50, or 60A. Higher amperage connectors have physically different pin layouts — a 20A plug cannot insert into a 15A receptacle and vice versa.
P or R suffix
P = plug (the male end, on the cord). R = receptacle (the female end, on the wall or equipment). NEMA 5-15P is the plug; NEMA 5-15R is the wall outlet.

Connector specifications

Straight-blade (non-locking) and locking (L-series) configurations. Ampacity ratings at 25°C ambient — derate for higher temperatures.

Designation	Voltage	Amperage	Ground	Common Applications
NEMA 1-15	125V	15A	Ungrounded	Small appliances, Lamps, Chargers
NEMA 5-15P	125V	15A	Grounded	Computers, Office equipment, Consumer electronics
NEMA 5-20P	125V	20A	Grounded	Power tools, Medical equipment, Commercial appliances
NEMA 6-15P	250V	15A	Grounded	Air conditioners, Power tools, Lab equipment
NEMA 6-20P	250V	20A	Grounded	HVAC, Welders, Commercial equipment
NEMA 10-30P	125/250V	30A	Ungrounded	Dryers (legacy), EV chargers (legacy)
NEMA 14-30P	125/250V	30A	Grounded	Electric dryers, EV charging (Level 2), Large appliances
NEMA 14-50P	125/250V	50A	Grounded	EV charging, RV parks, Commercial ranges
NEMA L5-15P	125V	15A	Grounded	Industrial equipment, AV/entertainment, Generator connections
NEMA L5-20P	125V	20A	Grounded	Generators, Industrial panels, Portable equipment
NEMA L6-20P	250V	20A	Grounded	Data centers, PDUs, Server power
NEMA L6-30P	250V	30A	Grounded	UPS systems, Computer rooms, Industrial equipment
NEMA L14-30P	125/250V	30A	Grounded	Generator transfer, Portable generators, Emergency power

Connector detail

NEMA 1-15 — Ungrounded 2-prong. Household lamps, clocks, small appliances. Being phased out in favor of NEMA 5-15P in new construction.
NEMA 5-15P — Standard North American 3-prong. The most common plug in the US and Canada. Required in all new residential and commercial construction.
NEMA 5-20P — Identical to 5-15P but with a T-shaped neutral blade for 20A circuits. Common in commercial kitchens, workshops, and hospital-grade applications.
NEMA 6-15P — 250V grounded connector for air conditioners, workshop tools, and equipment that requires higher voltage at lower current.
NEMA 6-20P — 250V 20A connector. Common for commercial HVAC equipment, welders, and high-current workshop loads.
NEMA 10-30P — Older ungrounded 30A dryer connector. Largely superseded by NEMA 14-30P in new installations. Still found in pre-1996 residential wiring.
NEMA 14-30P — Current standard for electric dryers and many Level 2 EV chargers. Provides both 125V and 250V at 30A with full grounding.
NEMA 14-50P — Standard for EV chargers (Tesla NEMA 14-50 adapter), RV hookups, and high-current commercial cooking equipment.
NEMA L5-15P — Twist-locking version of NEMA 5-15P. Used in applications where vibration or accidental disconnection is a concern.
NEMA L5-20P — Twist-locking 20A at 125V. Common for generator transfer connections and industrial power distribution.
NEMA L6-20P — Twist-locking 250V at 20A. Widely used in data centers for PDU connections and server power supplies.
NEMA L6-30P — High-current twist-locking 250V. Used for computer room PDUs, UPS systems, and industrial equipment feeds.
NEMA L14-30P — Twist-locking 4-wire connector providing both 125V and 250V at 30A. Critical for generator transfer switches.

Hospital-grade NEMA connectors

Hospital-grade means more than a UL listing. It's a construction specification designed for patient care areas where equipment disconnection could be life-threatening.

Feature	What it means
Green dot	UL hospital-grade marking. Required for all receptacles and cords installed in patient care areas.
Brass contacts	Heavy-duty brass or nickel-plated brass rather than steel. Withstands 4,000+ insertion cycles vs. ~1,000 for commercial grade.
Cord grip	Reinforced strain relief at both plug and receptacle. Prevents conductor damage from cord pulls.
NEMA WD-6	Must meet NEMA WD-6 requirements for hospital-grade construction, tested under UL 498 for receptacles and UL 817 for cords.
Markings	"Hospital Grade" printed on the plug body. Required on all listed hospital-grade products.

NEMA 5-15P and NEMA 5-20P are the most common hospital-grade configurations. Required by NEC 517 in patient care areas, ICUs, and operating rooms.

Twist-locking (L-series) connectors

L-series NEMA connectors have curved blades that engage a twist-locking mechanism when rotated approximately 30° after insertion. They require a deliberate twist-then-pull to disconnect — accidental removal requires significantly more force than standard straight-blade connectors.

Common in industrial environments, generator transfer panels, and any application where vibration, mechanical shock, or accidental cord pulls would cause a problem. The locking mechanism adds a pull-out force of 100–200N depending on the connector model.

Important: L-series plugs are NOT compatible with standard straight-blade receptacles. A NEMA L5-20P plug will not insert into a NEMA 5-20R receptacle — they are entirely different physical connectors despite having the same voltage and amperage rating.

Shop NEMA power cords

4,000+ configurations in stock — standard, hospital-grade, locking, and custom. Talk to an engineer for help selecting the right connector for your application.