How to Prevent Condensation in Electrical Enclosures

Condensation with electrical warning sign

Though it may not seem like much of a concern at first glance, condensation is the bane of any enclosed space in a damp environment. The build-up of moisture can lead to a number of issues, especially when electronic and electrical components are involved. Corrosion, short-circuiting, diminished performance, dangerous electrical arcs, and expensive down time can all result from just a little bit of condensation in an enclosure over time. So, what is the best way to keep condensation out of a polycarbonate enclosure?

What is Condensation?

Condensation occurs when warm, humid air comes into contact with a cold surface. When a difference in air temperature becomes too great, the air becomes unable to hold moisture in the form of water vapor, causing that moisture to condense and form water droplets. Imagine drinking a frosty glass of lemonade on a warm summer day—the “sweat” that forms on the outside of the glass is a perfect example of condensation.

What Causes Condensation Inside an Enclosure?

Temperature Fluctuation

A change in temperature between the enclosure’s interior and exterior surfaces is a significant factor in the creation of condensation. If the interior surfaces are significantly warmer than the air outside, or vice versa, condensation can form. Many components frequently found inside electrical enclosures, such as variable frequency drives (VFDs), servo drives, indicator lights, programmable logic controllers (PLCs), and transformers, create heat buildup that could result in such a temperature differential.

Environmental Conditions

Outdoor enclosures placed in environments with high humidity levels (such as coastal areas or rainy climates) are naturally more at risk for condensation, as are enclosures located in washdown locations or areas subject to indoor humidity. The greater the difference between exterior humidity and interior temperature, the more likely it is that condensation could enter the enclosure.

Sudden Temperature Changes

Even if the enclosure is installed in a relatively stabilized environment, rapid or temporary temperature changes, such as moving the enclosure from a warm indoor area to a cold outdoor area, can cause the air inside to change quickly and form condensation.
Frequent Opening and Closing: As part of a larger installation, an electrical enclosure may often need to be opened and closed for inspection, maintenance, or just routine usage. But in environments like the ones mentioned above, these actions can introduce warm, humid air from the environment to the cooler surfaces inside the enclosure.

Lack of Ventilation

Without proper ventilation, any moisture that does accumulate inside an enclosure has no way of exiting it. Additionally, poor ventilation prevents the exchange of air between the interior and exterior of the enclosure, resulting in stagnant air that creates moisture and increases the likelihood of condensation.

Installation Problems

Water can enter an enclosure due to faulty installations, poor insulation, and the use of unrated components. Any openings, cut-outs, or holes (such as for conduit entry) on an enclosure are prime areas, if made improperly, for outside air to enter in, making way for condensation. Additionally, using materials that are not properly rated for the environment can sabotage the enclosure’s integrity and make it more susceptible to water ingress. Lack of insulation can create cold spots within the enclosure where moisture is more likely to condensate.

Various Unknown Issues

Sometimes it is not readily apparent what could be causing condensation to occur. Maybe it’s ingress due to water wicking up wire installations; maybe it’s insects that have eaten the gasket material and left an opening for unwanted moisture to enter (believe it or not, this happens!) 

Whatever the cause, the results of condensation inside enclosures are often the same: costly corrosion and dangerous electrical damage. So what can be done to avoid (or control) condensation?

How to Prevent Condensation in Enclosures

Proper Ventilation

This is key; the temperature and humidity inside and outside the enclosure can be equalized by ensuring a continuous flow of air. Using vents (such as AttaBox’s UL Type 4X Rated Non-Metallic Breather and Drain Vents) can help move air through the enclosure, carrying away any excess moisture and stabilizing the temperature differential.

Proper Material Type

Some materials, such as aluminum and copper, have a higher thermal conductivity, meaning they can more easily transfer heat than other materials. For example, when cold weather comes around, the interior of an aluminum or other metal enclosure may cool down more rapidly, becoming a prime spot for condensation to form. In areas with high temperature change, it’s a good idea to use enclosures made of materials with low thermal conductivity, such as AttaBox’s industry-leading Heartland series of polycarbonate enclosures, that can better insulate themselves against exterior heat or cold. Polycarbonate is also non-conductive, making it a common choice in areas where water may come into contact with electrical equipment.

Temperature Regulation

If at all possible, install the enclosure away from any serious temperature fluctuations or damp areas to ensure the highest chance of avoiding condensation. However, this can’t always be achieved; so, using a fan, air heat exchanger or other heating elements (such as anti-condensation enclosure heaters) can help raise or lower the temperature of the enclosure just enough to prevent condensation without damaging the enclosed components. Installing humidity sensors, too, can help you monitor relative humidity levels and evaluate the best way to balance the exterior and interior temperatures.

Proper Sealing and Insulation

If insulation is to be used to stabilize an enclosure’s internal temperature, it’s important to apply it evenly and thoroughly in order to avoid the creation of cold spots. Furthermore, the use of a gasket or seal between the enclosure body and cover is essential to prevent outside air and moisture from entering the enclosure. AttaBox’s robotically applied foam-in-place gasket ensures a complete seal, reducing the likelihood of unwanted temperature changes that can lead to condensation.

Regular Maintenance

Periodic inspection and maintenance of the enclosure can help you be proactive about preventing condensation. Regularly check for signs of moisture accumulation, corrosion, or mold growth that signal the occurrence of condensation and address any issues promptly in order to prevent even more significant (and costly) problems later on.


Keeping condensation away from your electrical enclosure might seem like a tricky challenge, but it’s not an insurmountable one. By better understanding how condensation occurs and utilizing these tips and tricks, you can keep your sensitive electronic components dry and help maintain the functionality and service life of your enclosure.

No sweat!