Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

NEMA Enclosure Standards for Electric Motors

Sponsored Links

The enclosures of electrical motors are standardized by NEMA (National Electrical Manufacturers Association) as:


Ventilation openings in shield and/or frame prevents drops of liquid from falling into motor within up to 15 degree angle from vertical.

Designed for reasonably dry, clean, and well ventilated (usually indoors) areas. Outdoors installation require the motor to be protected with a cover that does not restrict the flow of air to the motor.

Totally Enclosed Air Over (TEAO)

Dust-tight fan and blower motors for shaft mounted fans or belt driven fans. The motors mounted within the airflow of the fan.

Totally Enclosed Non-Ventilated (TENV)

No ventilation openings, enclosed to prevent free exchange of air (not airtight). No external cooling fan, relies on convection cooling.

Suitable where the motor is exposed to dirt or dampness. Not suited in very moist humid or hazardous (explosive) air.

Totally Enclosed Fan Cooled (TEFC)

Same as TENV with an external fan as an integral part of the motor. The fan provides cooling by blowing air on the outside of the motor.

Totally Enclosed, Hostile and Severe Environment

Designed for use in extreme conditions - moist and/or chemical environments. Not for hazardous locations.

Totally Enclosed Blower Cooled

Same as TEFC with external fan on a power supply independent of the inverter output. Full cooling even at lower motor speeds.

Explosion-Proof Motors

The motor ambient temperature shall not exceed +40oC. Motors are approved for the classes:

CLASS I (Gases, Vapors)

  • Group A - Acetylene
  • Group B - Butadiene, ethylene oxide, hydrogen, propylene oxide
  • Group C - Acetaldehyde, cyclopropane, diethel ether, ethylene, isoprene
  • Group D - Acetone, acrylonitrite, ammonia, benzene, butane, ethylene dichloride, gasoline, hexane, methane, methanol, naphtha, propane, propylene, styrene, toluene, vinyl acetate, vinyl chloride, xylem

CLASS II (Combustible Dusts)

  • Group E - Aluminum, magnesium and other metal dusts with similar characteristics.
  • Group F - Carbon black, coke or coal dust
  • Group G - Flour, starch or grain dust

CLASS III (Fibers and flyings)

  • Group G - Flour, starch or grain dust
Sponsored Links

Related Topics


Electrical engineering with units, amps and electrical wiring. Wire gauges, electrical formulas, motors and more.

Related Documents

Dust Explosions - Substances, Critical Temperatures and Concentrations

Critical temperatures and concentration parameters for substances like coal, zinc, uranium and more.

Electrical Enclosure Types by NEMA

Description of NEMA electrical enclosures types.

Electrical Motors - Frame Dimensions

Electrical motors NEMA frame dimensions.

Electrical Motors - NEMA Frame Assignments

NEMA frame assignments.

Electrical Motors Efficiency Ratings

NEMA - electrical motor efficiency ratings.

Hazardous Areas - North America Classification

North American hazardous locations classification with classes, divisions and groups

IP - Ingress Protection Ratings

IP - Ingress Protection rating is used to specify the environmental protection - or electrical enclosure - of electrical equipment.

NEMA - National Electrical Manufacturers Association

National Electrical Manufacturers Association.

NEMA Insulation Classes

Electrical insulation systems rated by standard NEMA classifications to maximize allowable operating temperatures.

Sponsored Links

Search Engineering ToolBox

  • the most efficient way to navigate the Engineering ToolBox!

SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!


We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.