NEMA Connector Guide

Connector specifications

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

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 Largely superseded by NEMA 14-30P in new installations.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.

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.