NEMA 3 and NEMA 3R Electronics Enclosure
There are several electrical devices and equipment installed outdoors and most people do not even notice. From junction boxes to electricity transformers, all of these are protected by an enclosure. Engineers know that our electrical devices are what keep and maintain our comfortable lifestyle. However, to protect these devices, the engineer should choose the proper electrical enclosure.
With this in mind, which NEMA-rated electronics enclosure cabinets are considered weatherproof?
Commonly, these are the NEMA ratings ideal for weatherproof applications:
- NEMA 3 and its subsets
- NEMA 4 and NEMA 4X
- NEMA 12
But for this article, we will discuss NEMA 3 and its subset, NEMA 3R.
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.
| Protection Against the Following Conditions | NEMA 3 | NEMA 3R |
|---|---|---|
| Indoor Use | ✔︎ | ✔︎ |
| Outdoor Use | ✔︎ | ✔︎ |
| Access to hazardous parts | ✔︎ | ✔︎ |
| Ingress of solid foreign objects | ||
| Falling dirt | ✔︎ | |
| Circulating dust, lint, fibers, and flyings ** | ✔︎ | |
| Settling airborne dust, lint, fibers, and flyings ** | ✔︎ | |
| Windblown dust, lint, fibers, and flyings | ✔︎ | |
| Ingress of water | ||
| Dripping and light splashing | ✔︎ | |
| Hosedown and splashing water | ||
| Rain, snow, and sleet *** | ✔︎ | ✔︎ |
| Sleet **** | ||
| Occasional temporary submersion | ||
| Occasional prolonged submersion | ||
| Oil & Corrosion resistance | ||
| Oil and coolant seepage | ✔︎ | |
| Oil or coolant spraying and splashing | ||
| Corrosive agents |
