Understanding NEMA Standards for Electrical Enclosures


The National Electrical Manufacturers Association (NEMA) has developed rating standards for electrical enclosures. Each rating has different specifications, but all of them are designed to help protect electrical components, personnel, and property from damage.

Some of the most common types of NEMA enclosures are described below.

NEMA Type 1

Most commonly used for indoor commercial applications such as junction, switch, and utility boxes, NEMA Type 1 electrical enclosures require the least amount of protection. They can be found in environments with some risk of falling dirt, but no risk of airborne contaminants or exposure to splashing liquids.

Because they are already in relatively protected environments, filtered fans are typically sufficient to cool NEMA Type 1 enclosures.

NEMA Type 3R

Used for applications such as meter cabinets or utility boxes, NEMA Type 3R enclosures can be used either indoors or outdoors. Because they are designed to be weatherproof, they can withstand elements such as rain, snow, and windblown particles.

Filtered fans are commonly used for NEMA Type 3R enclosures.

NEMA Type 4

Typically used in industrial applications such as wiring enclosures, hydraulic controls, and operator consoles, NEMA Type 4 enclosures are watertight. Designed to protect against all types of weather and direct hose blasts in factory washdown environments, these enclosures must use a closed-loop cooling system to ensure that no contaminants enter the unit.

Depending on the ambient temperature surrounding the enclosure, either air to air heat exchangers or air conditioners can be used for NEMA Type 4 enclosures.

NEMA Type 4X

Similar to the specifications for NEMA Type 4 enclosures, the Type 4X designation provides additional protection against corrosion. They are often found in marine environments; industrial food processing; water treatment; oil and gas drilling, refining and processing; and paper manufacturing applications.

Both air to air heat exchangers and air conditioners are suitable closed-loop cooling systems for a NEMA Type 4X enclosure, again, depending on the ambient temperature.

NEMA Type 12

Enclosures of this type are designed to be dust-tight for indoor use, but not necessarily as watertight as NEMA Type 4 enclosures. Although they do provide protection against some splashing, they do not provide sufficient protection in an extreme washdown environment with high-pressure hoses.

A closed-loop cooling system is required for NEMA Type 12 electrical enclosures.

Thermal Edge is here to help you select and install cooling systems for NEMA rated electrical enclosures. We provide all of the equipment you need to ensure that your enclosure meets the recommended standards and keeps your valuable equipment protected. Contact us today to schedule a consultation.

Which types of NEMA enclosures do you encounter in your business?