NEMA 3 vs. 3R: Understanding the Difference and How To Choose

Knowledge Base for common NEMA Electrical Enclosure Ratings

‍

The question in terms of which electrical enclosures are suitable for your application, environment and give enough protection to your equipment, but not overwhelming and make you overpay for it? Words like “waterproof,” “weatherproof,” “water or rain resistance”, “corrosion resistance” and the like are used to describe the characteristic of electrical and electronic enclosures. Unfortunately, these terms are not clear enough and not clearly comparable to each other, inherently ambiguous indeed. Is the protection from rain, how much rain can it protect? how is it submerge in the water also how long, deep can the enclosure be submerged under the water?T

he following charts provide a general comparison of the most common NEMA rated enclosures, defined by The National Electrical Manufacturer’s Association (NEMA). These ratings represent the standard to specify enclosures with the right level of protection from both liquid and solid objects for industrial applications per NEMA 250-2003. Most commercial and industrial facilities require enclosures that can protect electrical wiring & equipment from adverse weather conditions including heavy rain, snow, ice formation and from potentially harmful wash-down cleaning with alkaline solutions. The chart provides short descriptive definitions for each category that is helpful to engineers, designers, equipment installers and other interested individuals. For more detailed information, refer tonema.org(“Enclosures for Electrical Equipment (1000 Volts Maximum)”). Call Nemaco if you have any additional technical questions about electrical enclosures.

‍

What are NEMA 250 type 3 rating?

NEMA 3 enclosures are manufactured and designed to protect household electrical controls, rotating equipment, generator skids. Also, they protect equipment used aboard ship docks, construction sites, and even equipment used in subway systems or tunnels.These are the main hazards NEMA 3 protects against:

• Accidental personnel contact
• Solid protection from dust and airborne particles
• Water ingress protection from rain, sleet
• Ice formation protection

Common applications for NEMA 3 include:

• Circuit breaker and boxes
• Junction boxes
• Security systems
• Farming equipment
• Air conditioning or heating equipment
• A/V systems installed outdoors
• Utility meters

‍

What are NEMA 250 type 3R rating?

NEMA 3R enclosures are designed for both indoor or outdoor nonhazardous applications. They offer protection similar to NEMA 3 but are optimized for regular weather conditions. Heavy rainfall can still cause ingress in a plain NEMA 3, so 3R is the smart choice for rain-resistant applications.Type 3R enclosures are commonly found in residential, commercial, and some industrial settings, protecting safety switches, mobile power distribution, and similar equipment at a very low cost.

‍

‍