Sheet Metal Enclosures and NEMA Standards

Sheet metal fabrication-prototypesUsing sheet metal enclosures, whether during the prototyping phase or during full-scale production, can play a critical role in maintaining safety both inside and outside the device. Many firms use the standards created by the National Electrical Manufacturers Association (NEMA), but engineers and designers may not know what protections each offers. Whether it has to do with liquids and rainfall, resistance to entrance of fibers or corrosive agents or other needs, one standard or another will likely meet the application you are looking to build out.

Sheet Metal Enclosures for Interior Placement

There are 10 NEMA enclosure types for indoor usage, but there are substantial differences in terms of what protections they offer to any circuitry or equipment inside the sheet metal enclosure, as follows:

Sheet Metal Assy ComponentsNEMA 1 and 2 enclosures can be ventilated for applications where heat can be an issue. In spite of that, both offer protection to users from live wires and circuits, as well as protection against falling dirt. A type 2 enclosure will also protect against some dripping or splashing water.

Type 4 and Type 6 enclosures both add protection against dust and fibers, whether circulating or settled as well as from splashing water or if the area around the enclosure needs to be hosed down. Type 4X and 6P adds protection against corrosion, while the latter can also be used when the enclosure will be submerged in water for brief periods of time.

Type 12 and Type 13 enclosures should be used in areas where there is the possibility of oil and coolant leakage, such as in engine rooms or near generators. Type 12 and Type 12K offer the same protections as Type 4 and Type 6, however while there is protection against non-water liquid seepage, spray and submersion protections are not offered. Type 13 builds on that limiting the damage from spraying and splashing from these materials.

Outdoor Sheet Metal Enclosures

All sheet metal enclosures for outdoor applications that meet NEMA standards will protect maintenance staff and other employees from access to hazardous parts inside the part, as well as from rain, snow and sleet. The other protections vary based on type:

NEMA Type 3 Variants: The type 3 protects against dust and other fibrous materials. The 3R does not, but can be ventilated for applications where heat is an issue. The 3S is used in applications where icing or sleet can occur. Adding an X to the designation, such as 3SX, means that any of these enclosures also affords protection against corrosion from acid or basic solutions.

Type 4 and Type 6 Enclosures: As with other standards, an X designation means the enclosure will protect against corrosion. Type 4 and Type 6 enclosures are designed for use in areas where hosedowns are required and limit the ingress of water. Type 6 enclosures can also be partially submerged and Type 6P enclosures provide extended submersion protection.

Issues with Hazardous Materials

There are four NEMA enclosures for use in applications where hazardous materials can be an issue, listed as Types 7 through 10. Types 8 and 9 require the sheet metal enclosures be able to prevent combustion when certain materials are introduced into the system, with type 8 allowing a box to function and limit explosions when it is submerged in oil and type 9 doing the same with flammable particles near or on the enclosures. Types 7 and 10 protect the environment around the devices if an explosion or fire occurs within the box itself.

Further Information and Planning Your Enclosure

The full list of NEMA enclosure types offers even more information. Local companies looking to build out enclosures can also consult with a sheet metal fabrication company in Bucks County to find the best option for their needs and expected location of any applications.

Keep in mind that you may wish to change the NEMA enclosure type following testing. Taking advantage of a small-scale run of sheet metal enclosures allows for real-world observations. Engineers may find, for example, that they can use a less expensive enclosure because the likelihood of the application including extensive spraying of water, coolant or oil are less than previously thought. A consultation with an experienced precision sheet metal fabrication company can also help a customer figure out what enclosures best fit their needs, whether on the initial prototype or after testing for manufacturing needs or to pass various certifications.