NEMA 4 enclosures

What Is a NEMA 4 Enclosure & Why Do Phase Converters Use Them?

A NEMA 4 enclosure surrounds the internal components of a phase converter to protect it from environmental elements such as dirt, dust, water, and corrosion. The enclosure is designed to prevent damage to the internal electrical equipment that would render the system incapable of powering your projects. We have created an outline of what a NEMA 4 enclosure is, its characteristics, and the different NEMA ratings.

NEMA 4 Enclosures

A NEMA 4 enclosure is a type of enclosure system that protects internal electrical equipment from water and dust. These enclosures are rated based on their ability to protect equipment from the elements. NEMA enclosures are rated in accordance with the National Electrical Manufacturers Association (NEMA). The higher the rating, the better protection they offer against dust, water, and other damaging environmental factors.

NEMA 4 enclosures are typically used in industrial settings where there is a high risk of liquid or water damage. They are also often used as safety barriers around hazardous materials or equipment.

NEMA 4 Enclosure Characteristics

In addition to protecting electrical equipment from the intrusion of harmful environmental elements, NEMA 4 motor enclosures have some key characteristics:

  • Seal-tight door
  • Steel or aluminum construction
  • Durable
  • Airtight
  • Built for indoor and outdoor use

Main Types Of NEMA Ratings for NEMA Enclosures

Every NEMA enclosure receives one of the following ratings: NEMA 1, NEMA 3, NEMA 3R, NEMA 3RX, NEMA 4, NEMA X, and NEMA 12. The higher the rating number is, the more protection the enclosure provides against dirt, water, and other damaging environmental factors. Besides providing varying levels of protection, each NEMA rating differs in application use and corrosion prevention.

Check out our NEMA rating guide below before choosing which enclosure is right for you:


Any NEMA enclosure will have a minimum NEMA 1 rating. This is the baseline level for NEMA system ratings. Enclosures with a NEMA 1 rating are designed to prevent some solid objects—such as dirt or grass—from falling in and damaging the internal electrical equipment. These enclosures are intended primarily for indoor use.


Enclosures with a NEMA 3 rating can be used both indoors and outdoors. They protect internal electrical equipment against solid objects, water, and external ice formation. The NEMA 3 enclosure features a protective barrier between the inside and outside of the enclosure containing no opening that would allow contact with energized parts. These enclosures are mostly used for low voltage, low current applications.

Tips & Insights: What Is Three-Phase Power? Applications & Advantages


Like enclosures with a NEMA 3 rating, NEMA 3R enclosures are designed for indoor and outdoor use. They’re resistant to solid objects, external ice formation, and corrosion and provide greater protection against water damage than NEMA 1 or NEMA 3 enclosures.


NEMA 3RX enclosures can be used for indoor and outdoor applications to protect internal equipment against solid objects, water, external ice formation, and corrosion. However, these NEMA enclosures don’t protect against fine dust particles that travel through the air. If you want the enclosure to block out dust particles, you’ll have to add a separate ventilation component.


NEMA 4 enclosures prevent dust and rain from entering the system while protecting the internal components from ice that forms on the exterior. You can use NEMA 4 enclosures for indoor and outdoor applications.


NEMA 4X enclosures have the same features as NEMA 4 enclosures with the bonus of protecting against corrosion. Since they protect against corrosion and can withstand harsh environments, they’re designed for outdoor applications. However, they’re effective for indoor applications also.


NEMA 12 enclosures are designed for industrial indoor use only and prevent dirt, dust, and similar particles from falling inside and damaging the electrical components. These NEMA enclosures also protect against water damage due to dripping or splashing.

phase converters with NEMA 4R enclosures

Our Rotary Phase Converters Are Engineered With NEMA 4R Enclosures

We want every customer to purchase long-lasting products. This is why we protect our rotary phase converters with durable NEMA 4R enclosures.

Features Of a NEMA 4R Enclosure:

  • Carbon steel construction that withstands harsh weather conditions
  • Intended for both indoor and outdoor use
  • Protects circuits from dust, debris, water, and corrosion
  • Includes a wall mount phase converter panel

View Our Selection Of Rotary Phase Converters

If you want a rotary phase converter that offers long-term protection against damaging environmental elements, go to the experts at Phoenix Phase Converters. We design, develop, and manufacture single phase to 3 phase converters to fit the specifications of your application. By using durable materials, we craft products that are made to last.

We offer the best-priced, most reliable rotary phase converters on the market. View our large selection of phase converters and equipment. When you need a product that will supply reliable single and three-phase power, trust our team to help you find the correct equipment.