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Glossary of Terms - All Terms

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Glossary Subsets


The National Electrical Code (NEC) is the standard of the National Board of Fire Underwriters for electric wiring and apparatus, as recommended by the National Fire Protection Association.

Needle Roller

A cylindrical roller of small diameter, with a large ratio of length to diameter.

NEMA 1 Enclosure

A general purpose electrical enclosure. For indoor use where oil, dust, and water is not a problem.


National Electrical Manufacturers Association. A non-profit trade association supported by the manufacturers of electrical apparatus and supplies. NEMA sets standards to facilitate understanding between the manufacturers and users of electrical products.

NEMA 12 Enclosure

An electrical enclosure used for excluding oils, coolants, flying dust etc.

NEMA 2 Enclosure

A driptight electrical enclosure. For indoor use. Excludes falling moisture and dirt.

NEMA 4 Enclosure

A watertight electrical enclosure required for hose down applications or other applications where water comes from any angle.

NEMA 5 Enclosure

A dust tight electrical enclosure used for excluding non-hazardous dust.

NEMA 3 Enclosure

A weatherproof electrical enclosure that provides protection against rain, sleet and snow.

NEMA 9 Enclosure

A dust tight electrical enclosure used for applications where combustible dust is present. Acceptable for Class II Groups E, F and G.

Newton Meter (Nm)

Metric unit of measure representing force.


The point common to all phases of a circuit. The neutral in most systems is grounded at or near the point of service entrance only and becomes the grounded neutral.


Any unwanted voltage or current in an electrical circuit.


National Pipt Taper (requires pipe sealant)


National Pipe Taper Fuel or Dry Seal Pipe Threads (may not require pipe sealant)