Housing for outdoor applications

In the previous article we described the application for indoor use. This is the most common application. Yet there are many applications to devise of evacuation systems used outside buildings. Think in particular about the industry sector, where safety is a serious issue. There are some good manufacturers for so called outdoor housing. Also there is the housing 19’’ constructions standard and the same arguments as in the previous article apply here.

‘’Housing for outdoor application requires a little more attention’’

A serious problem outside is moisture and temperature and there is no way to escape from it.

Moisture attracts from the ground and increases the humidity. This humidity creates condensation. Moisture arises caused by heating from the outside which will condense on the inside of the cabinet, or worse: on the electronics. Enabled electronics usually produce a small amount of heat, so condensation will not likely get on it. However, condensate that deposits on the ceiling of the housing can easily drop on the electronics and that is a serious problem. Therefore, measures must be taken inside the cabinet.

I am a great believer in fully enclosed cabinets in an outdoor environment without mechanical ventilation. A good solution is a roof edge put over the wall of the cabinet, which forms an air gasp. This gasp should be covered with a cotton filter. By natural convection, the heat can get out of the cabinet. You can see this kind of application for example in the telecom world and the system cabinets for example in the traffic world.

Dust and soot are even a bigger problem at outdoor use than indoor use. At outdoor housing with many vents you can see that the system components look awful after several years. Also the connectors of cables and electronics modules should be of higher quality when used in outdoor applications

‘’Due to the large temperature fluctuations and corrosive environment these kind of components suffer a lot more and this a serious cause of failure’’

Temperature is not a major issue anymore for electronics components nowadays. Modern electronics operate smoothly between -20 and +65 °C. In most cases electronics function better in a cold environment instead of a warm one. Heat creates more wastage. Due to an increased heat, a component can be less cooled. This has a great influence on semiconductor material, the basic of nearly all electronics.

The influence of temperature on mechanical items, such as connectors or installing a module in a rack, is of greater importance on the durability of the system than the wastage of a component.