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Take the “Dry” Road – Prevent Condensation in your NEMA 4 Enclosure

When it comes to designing enclosures that contain electronics for maximum longevity, many factors must be considered, including geographic location, temperature, moisture exposure, and the risk of induced condensation. Some designers assume that their NEMA enclosure is waterproof, and so…why worry about all that?

In a recent Stack Exchange web post (https://tinyurl.com/4cmzph46), the author asked for help regarding a sealed electronics enclosure that “had the top cover … screwed on properly, and there was no way water (could) get in.” However, there was clear evidence of condensation after investigation of an intermittent functional failure. 

How did this happen?

There is a misconception that NEMA 4 enclosures provide all the protection needed to prevent moisture-related failures. Even though NEMA 4 is recognized as the standard for keeping moisture from entering an enclosure – it does NOT prevent condensation-induced risks. 

Condensation is caused by warm moist air coming into contact with a surface that is colder than the air’s dew point. Most designers know to account for extreme temperature swings and relative humidity; great designs also account for the condensation-induced use case. 

Induced condensation can stem from two scenarios:

  1. high humidity in combination with day-to-night temperature swings (in some parts of the world, temperatures exceed +50°C. In others, they fall to –40°C), or
  2. heat generated from running electronics in combination with ambient cold temperature (less widely known).

Either scenario above could result in undesired condensation. Over time, the electronics exposed to this scenario could lead to potential device failure, manifested as a short circuit, corrosion, or contamination by mold and other organisms. These could also lead to unexpected water drainage from enclosures and the potential risk of shock to employees.

Beyond the physical issues created, consider the time and resources spent finding a malfunctioning terminal or other electrical components that have been affected by moisture is somewhat difficult as any related problems are not always critical in the first place. As the malfunction triggers inconsistent product performance, the maintenance team must manually check all the electrical components. If there are a hundred electrical boxes to check, the time required to go through all of these can be extensive and result in increased operational costs.

There are different tools to minimize condensation inside enclosures. The most effective tool is a comprehensive design, taking into consideration temperature and condensation. To protect the user and technician, enclosure designs must include devices to compensate for temperature (i.e., thermostat) and condensation (Hygrostat).

Don’t assume that NEMA fixes all that ails you. If you aren’t sure about your design and withstanding pesky condensation, reach out to one of our experts.

Designing complex electronics that perform perfectly outdoors is, well, complex. At STEGO, we believe that protecting those complex projects from extreme climates should be the simplest part of your design. That’s why we use German engineering to create the highest quality thermal management components to protect your designs from anything Mother Nature throws at it. We’ve been pioneering Thermal Management for over 40 years now. With STEGO parts installed, you can rest easy that your complex design is reliably protected for the long haul.