Applications for Weatherproof Enclosures(blogger@L-com.com)
When we talk about weatherproof enclosures, we really mean weatherproof. Not just a simple plastic box to keep out the occasional light rain, but heavy duty boxes, many of them NEMA rated, designed for one purpose: provide extreme protection for the sensitive electronic equipment that you must install outdoors.
Extreme protection involves many things: protection from dust, dirt, grease, and oil; protection from water, either light sprinklings or outright downpours; protection from theft and tampering when installed in an unsecure location; and protection from unusual heat and sub-zero cold. While there are a huge variety of weatherproof enclosures out there, the biggest challenge of installing electronics outdoors is temperature fluctuation.
Installations in Cold Environments: Heating Options
Slightly cold temperatures are not usually a problem for electronics. In the process of normal operation, they generate some heat and, so long as they are relatively dry, slight cold won't hurt anything. It's when you get down to really cold temperatures (anywhere in the 30°F/0°C range) that problems start. For most of these applications, a heated enclosure will serve, though there are sub-zero heated enclosures available with extra insulation and a stronger heater system to withstand temperatures as low as -30°F/-34°C.
All of these systems work with a thermostat-controlled heating system that does not turn on until the temperature drops to a certain level (usually around 40°F/4°C). Once on, they provide soft, radiant heat that, when coupled with the enclosure's insulation, provides a good environment for electronics to operate in, regardless of what is going on outside of the enclosure. Power can be provided using an 802.3af Power-over-Ethernet supply, which can be "tapped" inside the router with a standard PoE midspan. The heater is mounted underneath the mounting plate and does not require an AC plug, allowing you maximum space to mount the equipment you need.
Installations in Hot Environments: Cooling Options
Because most electronics produce heat when they are operating, warmer conditions are a much more common, and more challenging, application. For many of these, a simple vented weatherproof enclosure may be all you need. These enclosures feature vents in the door that are small (so to prevent unauthorized tampering with the equipment within) and downward-facing (to prevent rain and splashed water from getting in through the vents). They will allow a transfer of air from within and without the enclosure that is enough to keep the electronics from overheating in most environments.
However, in environments where the air is still or greater cooling is required, there are enclosures equipped with cooling fans to maximize airflow and protection for the equipment. These enclosures can have either one inbound fan, or two fans with one inbound and the other outbound. They usually include filters to prevent dust and dirt from being sucked in by the fan, which can be removed and cleaned periodically. Like the heated enclosures, they can get power from PoE taps or midspans installed in the enclosure.
Enclosures for Frequently Changing Temperatures
Coming from someone in New England, where the oft-repeated saying is: "If you don't like the weather in New England, just wait a few minutes", I know that temperature changes outside really can frequently vary. Therefore, enclosures with both heating and cooling elements are very justified in many applications. They provide the best of both worlds, with thermostat-controlled heaters and fans to ensure the equipment within is provided extreme protection.