Electrical Terms Definitions

Note: the following are very brief descriptions of some terms used in the US.  For expanded definitions and exact requirements, please refer to the latest edition of the codes and specifications involved, or refer to your local electrical codes and regulations.

Explosion proof:

As defined by the National Electrical Code (latest edition).  Is divided into Class I (gasses and vapors) Groups A, B, C, and D and Class II (dusts) Groups E, F, and G.

Class I, Group D:

Contains the National Electrical Code provisions for electrical installations which may contain ammonia, gasoline, hexane, natural gas, or other similar vapors.

Class II, Group G:

Contains the National Electrical Code provisions for electrical installations which may contain flour, grain, or similar dust.

National Electrical Code (NEC):

A division of the National Fire Prevention Association (NFPA) that issues standards for the installation of electrical equipment and systems.

National Electrical Manufacturers Association (NEMA):

A group which issues standards for the manufacture of electrical equipment.

NEMA enclosure types: (abbreviated) (IEC equivalents in parenthesis)

· Type 1: General purpose—indoor. (IP10)

· Type 2: Dripproof—indoor (IP11)

· Type 3: Dusttight, raintight, sleettight—outdoor (IP54)

· Type 3R: Raintight, sleet resistant—outdoor (IP14)

· Type 3S: Dusttight, raintight, sleettight—outdoor (IP54)

· Type 4: Watertight, dusttight, sleet resistant—indoor and outdoor (IP56)

· Type 4X: Watertight, dusttight, corrosion-resistant—indoor and outdoor (IP56)

· Type 5: Dusttight, drip-proof—indoor (IP52)

· Type 6: Occasional submersion, watertight, sleet resistant—indoor and out (IP67)

· Type 6P: Prolonged submersion. Watertight, sleet resistant—indoor and out (IP67)

· Type 12: Dusttight and driptight—indoor (IP52)

· Type 12K: Dusttight and driptight, with knockouts—indoor (IP52)

· Type 13: Oiltight and dusttight—indoor (IP54)

· Type 7: Class I , Groups A, B, C, or D—indoor

· Type 8: Class I , Groups A, B, C, or D—indoor and outdoor

· Type 9: Class II , Groups E, F, or G—indoor

· Type 10: Requirements of Mine Safety and Health Administration (MSHA)

· TEFC : Totally enclosed, fan cooled (IP54 min.)