What to Consider When Selecting Enclosure Cooling for NEMA Type 4X


A NEMA 4X rated enclosure is used when the enclosure is subject to harsh conditions, such as water sprays and corrosive substances, which could result in damage to internal components.

Enclosure cooling equipment designed for use with such enclosures must be built to the same standards, and its addition should not impact on the overall enclosure rating. Here are some things to consider when selecting enclosure cooling equipment for NEMA Type 4X enclosures.

Corrosion Protection

It’s necessary to carefully evaluate the enclosure cooling equipment materials of construction. The NEMA 4X corrosion test requires exposure to salt spray for 200 hours. These conditions do not necessarily replicate actual site conditions in an environment where other corrosive vapors are present. It’s best to look for stainless steel construction and ensure that any exposed refrigeration tubing is protected with a corrosion resistant coating.  If the enclosure will be located in a marine environment, 316 stainless steel is preferable to 304 stainless steel due to its increased corrosion resistance..

Sealing Against Dirt, Dust, and Pollutants

The enclosure should resist windblown dirt and pollution. Check that the evaporator section of the cooling system is completely sealed to ensure no dirt can enter the enclosure. Additional points to look for include welded seam construction and effective sealing measures where tubing passes through bulkheads.

Protection Against Hose Directed Water

NEMA 4X enclosures have to withstand a water jet of 65 gallons per minute from a one inch diameter nozzle. The sealed evaporator section needs to provide this level of protection. Also, look for a design that doesn’t allow water to accumulate in places where mold could grow, and verify that the sealing gasket between the cooling system and enclosure is watertight.

Cold Weather Resistance

A particular requirement of a NEMA 4X enclosure is that there should be no damage caused by the formation of ice on the enclosure. This includes damage to any fitting such as the controller and filters, and it’s worth verifying with the supplier that moving parts such as the condenser circulation fan are unaffected by the enclosure being encased in ice.

Solar Heat Load

Another issue to consider is the effect of solar radiation. NEMA 4X enclosures are designed for outdoor use in harsh climates and will be subject to solar radiation during summer. The cumulative heating may be significant and should be taken into account in the heat load calculations. However, it’s worth noting that stainless steel has a much lower solar absorption ratio than painted steel so stainless steel enclosures will absorb less heat from the sun.

Choosing a NEMA 4X Cooling Solution

Thermal Edge’s range of NEMA 4X enclosure air conditioners and air to air heat exchangers are designed and built to the highest standards. Housings are made from 304 or 316 stainless steel with welded construction that is robust and long lasting, offering a high level of equipment protection. For guidance in selecting the right enclosure cooling solution, please contact our Sales Engineers.