Understanding NEMA Standards

The National Electrical Manufacturers Association (NEMA) includes over 700 standards and application guides, as well as providing business analytics and advocacy for electrical equipment manufacturers.

NEMA Standards

NEMA Standards contribute to the design, manufacturing, and distribution of electrical equipment. The standards are relevant to products like electric immersion heaters, lighting, utility, building, and transportation systems.

The standards improve the selection of materials, equipment, and processes. This helps to maximize safety for people, property and the environment. As well, standardization has a direct financial benefit to organizations, streamlining operations, growing markets, and reducing costs.

NEMA codes and standards are selected, revised, and approved by committee. To pass a vote, new standards must consider the interests of all affected, comply with policies and procedures, and be technically sound.

Document Types

There are several document types available under NEMA standards. But the basic approach to reading the standards is the same for all types. 

You start your search with a clear and specific goal. For example, searching for “replacing electrical wiring device,” would bring you to the Guidelines for Electrical Wiring Device Replacement standard.

Once you have selected the Standard, read its scope to make sure it covers your needs. The scope is a clear statement describing what is included in the identified standard. You may also see specific for application, dimensions, testing, or specific brand-name products. If the contents matches your needs, scroll to the table of contents and select the appropriate section. 


Standards are the most recognizable document type. They can be relevant to all readers, rather than specific roles or specialties. 

White Papers

White papers are also relevant to a wide audience. They can apply to everyone from the layperson to installers and engineers. The content is generally practical dealing with things like hazards identification and mitigation.

Application Guidelines

Guidelines are more specifically targeted than standards. They may be written for people with specific roles. For instance, employees who work directly with the product(s), installers, and inspectors.

Standards for Future Design

These standards are generally geared towards designers and engineers. As the name suggests, these documents provide information for future development and design.

Reference System

To identify or retrieve NEMA standards, there is a specific reference numbering system. Just as a library has the Dewey Decimal System, NEMA has its own alphanumeric system. The three elements of this reference system are: 

  1. A two letter designation referencing the product type or section. For instance, “MG” is used for products in the Motors and Generators section
  2. The numeric designation of that product section
  3. The publication date. The date may list the republication or reaffirmation date instead of the original publication date.


Proper usage of NEMA Standards are a great help in selecting the best electrical equipment, processes, settings, and application. For selecting or replacing electric immersion heaters, contact a Wattco representative to determine the ideal configuration for your needs and budget.