Understanding cabinet heaters

Author: Stephen Bosak


Do not get stuck in the cold wondering why your substation is down. Check your cabinet heaters now.


Why they are essential: Cabinet heaters are often found in applications on many types of outdoor electrical equipment. However, the term “cabinet heater” can be somewhat misleading.


Although a cabinet heater raises interior heat slightly above ambient temperature, it does this to perform its primary function, which is to prevent moisture from condensing inside the cabinet. The only time cabinet heater applications require a significant amount of additional heat is when they are located in colder climates, such as a -30°C environment. The heaters protect components that may be at risk when faced with extremely low temperatures.


Volume matters: Cabinets with a large volume of air space are more susceptible to condensation and often require additional heaters operated by a thermostat. The thermostat is key in cooler conditions when more heat is necessary to prevent condensation.


Even cabinets with vents to promote air movement are not exempt from needing another utility. Cabinet heaters more sufficiently prevent condensation and corrosion development on the metal surfaces.


Do not forget to seal the deal: Outdoor cabinets with conduit openings must have their apertures sealed. Using spray foam insulation is the most common method, although traditional duct seal compound is sufficient as well. Creating a seal is particularly important if the conduit exits into a cable trench or directly into the ground. This can generate a chimney effect which will cause moisture laden air to be drawn into the cabinet and ultimately produce condensation on the interior surfaces.


Moral of the story: With the colder weather moving in, take key factors such as temperature, sealing and volume into account when examining cabinet heaters.