How to Tell if a Motor is Water-Protected

In many electric motor applications, protection from water intrusion is especially important. Some applications, like those found in the food production industry, need motors that can stand up to the moisture and caustic chemicals used in washdown environments.

Knowing how to determine the level of protection and understanding the different levels of that protection can help you to increase the life of your components, leading to less unplanned downtime. Let us guide you through the options to ensure motor lifespan and protect your valuable equipment.

Grading Motor Resistance With Ingress Protection Ratings

Ingress Protection (IP) ratings grade the resistance of an enclosure against the intrusion of dust or liquids. These internationally-recognized ratings are published by the International Electrotechnical Commission (IEC) to explain how products can withstand various environmental factors.

IP ratings are represented by combining two rating numbers. The first number represents the protection against solid foreign objects. The second number represents the ability to withstand liquids. A third character (a letter) can be used to describe additional information but is often omitted.

Before a manufacturer can assign an IP Rating to a product, they must conduct independent testing. This ensures that the product provides the level of protection stated by the rating, allowing customers to determine if a product will meet the needs of their environment.

NEMA Designations Rate Enclosures and Environment

Like IEC, NEMA has designations indicating the protection provided by a motor’s enclosure. However, NEMA designations are in words, such as Open Drip Proof or Totally Enclosed Fan Cooled instead of the two-digit Index of Protection (IP) designation explained above.

Open Drip Proof (ODP) motors have venting in the end frame and/or main frame, situated to prevent drops of liquid from falling into the motor within a 15° angle from vertical. These motors are designed for use in areas that are reasonably dry, clean, well-ventilated, and usually indoors. If installed outdoors, ODP motors should be protected with a cover that does not restrict air flow.

Totally Enclosed Non-Ventilated (TENV) motors have no vent openings. They are tightly enclosed to prevent the free exchange of air but are not airtight. TENV motors have no cooling fan and rely on convection for cooling. They are suitable for use in applications exposed to dirt or dampness, but not for hazardous locations or applications having frequent hose downs.

Totally Enclosed Fan Cooled (TEFC) motors are the same as TENV except they have an external fan as an integral part of the motor to provide cooling by blowing air over the outside frame. Totally Enclosed Air Over motors are specifically designed to be used within the airflow of the fan or blower they are driving. This provides an important part of the motor’s cooling. Totally Enclosed Hostile and Severe Environment motors are designed for use in extremely moist or chemical environments, but not for hazardous locations.

Explosion Proof motors meet Underwriters Laboratories or CSA standards for use in the hazardous (explosive) locations shown by the UL/CSA label on the motor. The motor user must specify the explosion proof motor required. Locations are considered hazardous because the atmosphere contains or may contain gas, vapor, or dust in explosive quantities. The National Electrical Code (NEC) divides these locations into classes and groups according to the type of explosive agent.