The NEMA Numbering System

Posted on 1/16/17 12:00 AM

NEMA (National Electrical Manufacturers Association) has a variety of standards for electrical manufacturers. This is so that consistency and safety can be achieved. A numbering system has been created to standardize the description and rating of NEMA plug and socket patterns.

The NEMA pattern and numbering system consists of four main identifiers.

First Identifier

The first identifier can be blank or have the letter “L.” This determines whether the device will use straight or locking blades.

Second Identifier

The second identifier is a number which determines the voltage rating. For example:

“1” identifies that the configuration is rated for 125VAC, Class II
“5” identifies that the configuration is rated for 125VAC, Class I
“6” identifies that the configuration is rated for 250VAC, Class I

The rating given is the highest voltage allowed for use with the device by the standard, ANSI/NEMA WD-6. In a Class I application, the component must have the ability to provide grounding. In a Class II application, no grounding is required.

Third Identifier

The third identifier is also a number. This specifies the amperage rating. The amperage rating, like the voltage rating, is the highest amperage allowed for use with the device by the standard.