In meeting certain NEMA requirements, the design engineer should contemplate about an enclosures’ capability to withstand harmful environmental hazards. In this article, we will discuss how can each NEMA rating can effectively protect your equipment from environmental hazards.
Sheet metal enclosures
The metal sheet electrical boxes is equipped to effectively protect your equipment from solid and water ingress that can come from floating dust, debris or hose-directed/splashing water. Primarily, metal sheet electrical enclosures are designed to be able to meet NEMA requirements for its several ratings. However, if you need the electrical enclosure to be partially or totally submersed in water (like in marine offshore applications) then this material is not the best choice for you. Below are some guidelines that you can follow:
NEMA Type 1 Electrical Boxes: It is recommended to only use two simple piece enclosure style that is covered on top of the case. In this scenario, a L, U, or extruded electrical enclosure would suffice.
NEMA Type 2 Electrical Box: We best recommend to have overlapping flanges on the open seams of the case. To fasten the seams of the enclosure, you should use tack, sport, or plug welds. This can totally depend on the severity of the environment that you are in. For any engineering application, you might require a fully welded seams. The U-shape enclosure will work at its best when it has fewer welded seams.
NEMA Type 4, 4X: At best, it is recommended to have fully welded seams when you are using gaskets for your enclosure. Gaskets is a perfect use for anything that has to do with water being near or even for water being hose directed to the case. In some of the applications of enclosure gasket, the utilization of style foam strips or full gasket piece will be enough. You should do fastener sealing as soon as you notice that there will be water in the enclosure application. Therefore, you should seal the edges with fasteners.
One of the most strategic placement of fasteners to seal the edges is that they should not be too obvious inside the case. In addition to this, you can also do the following: assembling the edges with sealing screws and utilization of latch or lack to fasten enclosure.
If you want to achieve the type 4X for electronics enclosure, you should opt for a corrosion resistant sheet metal such as stainless steel, almuminum or galvanneal in order to fully achieve this rating.
NEMA Type 5 Electronics Enclosure: The use of overlapping flanges should be utilized on open seams of the electrical box or even fully welded seams. Totally depends on the type of environment you will use the enclosure in. For this type, U-shape enclosure would work the best.
If you are looking for any enclosure that can be partially or totally submerged in water, you can do the above recommendations. The recommendations on sealing can effectively meet NEMA Types 1, 2, 4(X) and 5 respectively. In line with this, these enclosures can be completely sealed as long as the right 0-rings or gaskets are made waterproof. This should be sufficient enough to protect your equipment form prolonged submersion in water by meeting the NEMA Type 6(P) standard.
Keep the following in mind when designing this type of enclosure for water immersion:
The enclosure should be designed in a way to minimize the number of seams to seal, with fewer parts and seams; there is less chance of water entering the enclosure.
There is one tip any design engineer should keep in mind when you are designing an enclosure for submersion application: the electrical box should be designed in a structure that the seams to seal will be minimized – requiring fewer parts and seams. With this in mind, there is a lesser chance of water entering the enclosure.