How do I prevent condensation build-up in outdoor enclosures?
Short answer
Condensation in outdoor enclosures is prevented by maintaining the correct IP rating, fitting properly sealed cable glands, and adding a pressure-equalising vent to release temperature-driven pressure changes without letting moisture in. In environments with large day/night temperature swings, an anti-condensation heater controlled by a thermostat or hygrostat keeps internal surfaces above the dew point.
Condensation in electrical enclosures is caused by water vapour in the air turning to liquid on cooler surfaces. There are several circumstances that can lead to condensation forming, so understanding which of these apply to your situation is essential in finding the best solution.
Temperature fluctuations: An enclosure cools rapidly, particularly at night or when equipment is switched off. If its internal temperature falls below the dew point, condensation forms.
High humidity: Moisture can enter through cable glands, door seals, vents or other openings. The higher the humidity, the more likely condensation becomes.
Temperature differences: An enclosure installed outdoors, in a cold room or close to chilled equipment may have surfaces significantly colder than the surrounding air.
Heating and cooling cycles: Internal equipment may generate heat during operation and then cool when switched off. This repeated cycling encourages condensation.
Poor enclosure design or sealing: Incorrectly fitted gaskets, damaged seals or unsuitable cable entries can allow humid air or water to enter.
Pressure changes: Heating and cooling cause air inside a sealed enclosure to expand and contract. This can create a ‘breathing’ effect, drawing humid outside air into the enclosure.
Spelsberg produces a wide range of enclosures that can be specified for a variety of applications and they include several features that minimise condensation build-up.
It is important to use correctly rated enclosures, appropriate gaskets and properly installed cable glands. Maintaining the enclosure’s IP rating helps prevent humid air and liquid water from entering.
A pressure-equalising vent can be specified to allow pressure changes caused by temperature fluctuations to occur without allowing liquid water and contaminants into the enclosure.
In outdoor installations and environments with large day/night temperature variations it may be necessary to install a small anti-condensation heater that maintains the internal temperature slightly above the dew point, preventing moisture from forming on components. A thermostat or hygrostat can control the heater to avoid unnecessary energy consumption.
Spelsberg produces enclosures and components that comply with the requirements of relevant European and North American directives, such as VDE (Verband der Elektrotechnik), EN (European Norm) CSA (Canadian Standard for Safety) and UL (Underwriter Laboratories) regulations.
We adhere to all these international standards also when delivering bespoke enclosures. We also provide certificates attesting that the products supplied are in accordance with the specifications defined by the customers, which can include technical drawings, material selections, specific IP ratings or fire resistance properties. If you’d like more specific information about certificates offered on Spelsberg electrical enclosures, please feel free to send me a private message.
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