Condensation in electrical enclosures

Glossary default By Rickard Andersson

Definition

Condensation in electrical enclosures occurs when moisture in the air changes into liquid water on internal surfaces or equipment.

This typically happens when the temperature of a surface falls below the dew point of the surrounding air. Moisture can then form on enclosure walls, electrical components, terminals, circuit boards, cables, and other internal surfaces.

Condensation can increase the risk of corrosion, electrical faults, insulation degradation, and equipment failure, making moisture control an important consideration when designing enclosures for changing or humid environmental conditions.

Context

Electrical enclosures are often designed to protect sensitive equipment from external environmental conditions such as rain, dust, and moisture.

However, a high level of ingress protection does not necessarily prevent condensation from developing inside the enclosure.

Moisture can already be present in trapped internal air or enter when an enclosure is opened for installation or maintenance. Changes in temperature can then cause relative humidity inside the enclosure to rise.

Outdoor installations are particularly susceptible because enclosure temperatures can change significantly between day and night. Similar conditions can occur in industrial facilities, unheated spaces, remote sites, and other environments exposed to temperature fluctuations.

Understanding temperature, humidity, and dew point is therefore essential when assessing condensation risk.

Technical insight

Condensation is primarily driven by the relationship between air temperature, moisture content, and surface temperature.

Warm air can contain more water vapor than colder air. As humid air cools, its relative humidity increases until it reaches saturation.

The temperature at which this occurs is known as the dew point. If an enclosure surface or internal component falls below this temperature, water vapor can condense on that surface.

Dew point

Dew point is the temperature at which air becomes saturated with water vapor and condensation can begin to form.

For example, an enclosure may contain relatively warm, humid air during the day. If the enclosure walls cool rapidly overnight, their surface temperature may fall below the dew point even though the ambient air temperature remains within the equipment’s specified operating range.

This means condensation risk cannot be evaluated from temperature alone. Relative humidity and changing surface temperatures must also be considered.

Temperature fluctuations

Rapid or repeated temperature changes can increase the risk of condensation.

Outdoor electrical enclosures can heat significantly during daylight because of ambient temperature and solar radiation. After sunset, the enclosure and its internal air can cool.

Equipment operation can create similar cycles. Internal temperatures may rise while equipment is active and fall when equipment is switched off or operates at a lower load.

These thermal cycles can repeatedly move internal surfaces above and below the dew point.

Moisture inside the enclosure

Moisture does not necessarily need to enter as liquid water for condensation to occur.

Humid air can enter during installation, maintenance, cable installation, or normal pressure changes caused by heating and cooling cycles.

Once moisture is present inside the enclosure, a sufficiently cold surface can cause condensation even when the enclosure provides a high level of ingress protection.

Risks to electrical and electronic equipment

Condensation can affect both the enclosure and the equipment installed inside it.

Potential consequences include:

Corrosion of metal components
Electrical short circuits
Reduced insulation resistance
Degradation of electronic components
Damage to terminals and connectors
Reduced equipment reliability
Premature equipment failure

Repeated condensation cycles can be particularly problematic because moisture exposure and corrosion can accumulate over time.

Preventing condensation

Condensation prevention generally involves controlling temperature, humidity, or both.

One common approach is to maintain the internal enclosure temperature above the dew point using a heater module. Even a relatively small increase in internal temperature can reduce relative humidity and help prevent surfaces from reaching condensation conditions.

Other approaches can include controlled ventilation, enclosure cooling, drainage, pressure equalization, insulation, and environmental monitoring.

The appropriate strategy depends on ambient conditions, enclosure design, equipment heat generation, ingress protection requirements, and the severity of the condensation risk.

Key advantages of condensation control

Reduces moisture exposure inside the enclosure
Helps prevent corrosion
Reduces the risk of electrical faults
Protects sensitive electronic equipment
Supports reliable equipment operation
Can extend equipment service life

Applications

Condensation control is relevant across applications where electrical and electronic equipment experiences humidity or temperature fluctuations.

Telecom and connectivity

Outdoor telecom and connectivity infrastructure can experience significant daily temperature changes, making condensation control important for cabinets containing network, power, and communications equipment.

Data center and IT infrastructure

Distributed data center and IT infrastructure can place sensitive IT equipment in outdoor enclosures, shelters, and edge locations where humidity and changing ambient temperatures create condensation risks.

Industrial automation

Electrical enclosures used in industrial automation may experience changing temperatures, washdown conditions, humidity, or unheated operating environments that increase the risk of internal condensation.

Energy and grid infrastructure

Outdoor equipment used throughout energy and grid infrastructure can experience changing weather conditions and temperature cycles that create moisture risks inside electrical enclosures.

Oil, gas and mining

Electrical and control equipment used in oil, gas and mining applications may operate in remote or demanding environments where humidity, temperature changes, and environmental exposure must be considered.

Defense and security

Outdoor electronics used in defense and security applications can require condensation control to support reliable operation across changing environmental conditions.

FAQ

Condensation occurs when a surface inside the enclosure falls below the dew point of the surrounding air. Water vapor in the air then changes into liquid water on the colder surface.

Yes. An IP rating describes protection against external ingress of solid objects and water but does not mean that condensation cannot occur inside the enclosure. Moisture already present in the internal air can condense when temperatures fall below the dew point.

Condensation can be controlled by managing temperature and humidity. Depending on the application, solutions can include enclosure heaters, controlled ventilation, cooling, insulation, pressure equalization, drainage, and environmental monitoring.

An enclosure heater can maintain the internal temperature above the dew point, reducing relative humidity and the likelihood that moisture will condense on equipment and enclosure surfaces.