NEMA Plug and Receptacle Chart: Common Configurations Explained

A NEMA plug designation is more than a model number. It identifies a standardized electrical configuration so a plug is physically matched to the receptacle, voltage, current rating, conductor arrangement, and grounding scheme it was designed to use.

For example, NEMA 5-20R is a 20-amp, 125-volt receptacle in the grounding NEMA 5 family. NEMA L14-30P is a 30-amp locking plug in the 125/250-volt NEMA 14 family. Once you know how the code is built, a plug-and-receptacle chart becomes much easier to read.

NEMA wiring-device configurations are standardized under ANSI/NEMA WD 6. The configuration system is intentionally keyed so devices with incompatible electrical characteristics cannot normally be mated simply because they look similar.

How to Read a NEMA Plug or Receptacle Number

Most common designations follow the same pattern: an optional L for a locking device, a configuration-family number, a hyphen, an ampere rating, and a P or R suffix for plug or receptacle.

The family number carries the electrical arrangement. The amperage after the hyphen does not tell you the voltage by itself. A 30-amp NEMA 5 device and a 30-amp NEMA 6 device are both rated 30 amps, but they belong to different voltage families and are not interchangeable.

Common Straight-Blade NEMA Plug and Receptacle Chart

Straight-blade devices insert and remove without a twist. The table below focuses on configurations electricians, facility teams, equipment buyers, EV owners, and RV users are most likely to encounter.

The familiar 5-20R has a T-shaped slot and is intentionally compatible with both 5-15P and 5-20P plugs. A 5-15R, by contrast, does not accept a true 5-20P plug. That one-way compatibility lets a 20-amp receptacle serve ordinary 15-amp cord sets without allowing a 20-amp plug into a 15-amp receptacle.

Common NEMA Locking Plug and Receptacle Chart

Locking configurations use an L prefix. The plug is inserted and rotated so the blades engage the matching receptacle or connector. Locking devices are common where vibration, movement, portable equipment, generators, temporary power, or accidental unplugging are concerns.

For products in this category, Lumera Electric groups common locking configurations under its twist-lock devices selection. Match the complete designation on the plug and receptacle rather than selecting by amp rating alone.

Straight-Blade vs. Locking NEMA Devices

Straight-blade devices prioritize fast connection and disconnection. Locking devices prioritize retention. Neither style is automatically higher quality or safer in every application; the correct choice depends on the equipment, environment, circuit, and whether unintended disconnection is a realistic problem.

What NEMA 5, 6, 10, and 14 Actually Mean

NEMA 5

NEMA 5 is the common 125-volt grounding family. The 5-15 configuration is the everyday U.S. household plug and receptacle, while 5-20 adds the 20-amp T-slot arrangement.

NEMA 6

NEMA 6 is a grounding family for 250-volt circuits without a neutral. It is common on dedicated 240/250-volt equipment, shop tools, welders, and some EV charging equipment.

NEMA 10

NEMA 10 is a legacy 125/250-volt three-wire family that does not provide a separate equipment-grounding conductor. It remains relevant when identifying older dryer and range installations, but it should not be treated as the default for new work.

NEMA 14

NEMA 14 provides both 125- and 250-volt capability with a separate equipment ground. NEMA 14-30 is familiar on modern dryer circuits, while NEMA 14-50 is widely encountered with ranges, RV connections, generators, and plug-in EV charging. Lumera also carries dedicated EV charging receptacles and accessories for common 14-50 and 6-50 applications.

How to Match a Plug to the Correct Receptacle

1. Read the equipment nameplate first. Confirm required voltage, phase, and current before looking at connector shape.
2. Read the complete NEMA marking on the existing plug, receptacle, connector, or inlet. Do not identify a device only by a quick visual comparison.
3. Confirm grounding and conductor count. A 125/250V four-wire configuration is not equivalent to a three-wire legacy configuration.
4. Confirm whether the application needs straight-blade or locking retention.
5. Check the product grade and environment. Industrial, wet-location, outdoor, corrosion-prone, and high-cycle applications may need features beyond the NEMA blade pattern.
6. Verify the branch circuit and overcurrent protection. The receptacle configuration must agree with the actual circuit, not merely with the plug you want to connect.

Common NEMA Plug Selection Mistakes

• Assuming the number after the hyphen tells the whole story. It tells the ampere class, not the voltage family.
• Treating NEMA 6-50 and NEMA 14-50 as interchangeable because both are commonly 50-amp 240/250-volt connections. NEMA 14 includes a neutral; NEMA 6 does not.
• Mistaking TT-30 for a 240-volt receptacle. TT-30 is a 30-amp, 125-volt RV configuration.
• Using adapters to force incompatible equipment onto a circuit without confirming voltage, grounding, neutral, and load requirements.
• Choosing a 20-amp receptacle simply because a circuit has a 20-amp breaker. The wiring method, number of receptacles, equipment, and applicable code all still matter.
• Confusing NEMA wiring-device configurations with NEMA enclosure Types. They are different standards describing different product characteristics.

If you are comparing ordinary 15A and 20A wall devices rather than specialty plug patterns, Lumera’s outlet types guide explains the differences between 15A, 20A, tamper-resistant, weather-resistant, and GFCI requirements.

The Bottom Line

A NEMA chart is a compatibility map. Start with the electrical requirements, then match the full designation: family, amperage, grounding arrangement, locking or straight-blade style, and plug or receptacle suffix. Never choose by appearance alone, and never modify blades or use an adapter to bypass a configuration mismatch without verifying that the complete circuit and equipment are designed for the connection.