Outdoors, or in wet indoor environments like wash-down areas, Electronic Dry Cabinets of electronic systems start with the design of the enclosures and penetrations, and end with the design and configuration of the components. This article concentrates on a number of these best practices.
Assume your enclosure will leak. Unless the application form demands a vented enclosure (e.g., for heat dissipation, battery off-gassing), a sealed enclosure represents the very first line of defense against moisture. Unfortunately, even the most effective NEMA 4 electrical enclosure works well until poor installation practices or out-year modifications create poorly sealed penetrations (Fig. 1).
It’s advisable to believe that penetrations into any enclosure are going to leak (as shown by Fig. 2). Based upon this assumption, top-mounted conduit penetrations where moisture can collect on horizontal surfaces ought to be avoided. Even if Myers hubs or sealing locknuts are used for code compliance, enclosure penetrations needs to be made below energized parts, whenever possible.
When it comes to cable penetrations (versus conduit penetrations), directing water from the electrical enclosure or housing with the use of drip loops (Fig. 3) is yet another best practice. The next task is to heat-shrink the connector fittings and alternate wrappings of electrical tape and butyl self-adhesive rubber tape to guard against moisture intrusion in to the connector.
Maintaining door seals is essential. Door seals needs to be inspected to make certain panel doors are sealing properly by observing surface wear on the seals. Larger doors with few latches are particularly problematic as flexing of the door may prevent a uniform seal. Lastly, seals needs to be inspected for pinching, tears and proper adhesion to original mating surfaces.
Assume all conduits contain moisture
Another best practice for Dry Storage Cabinets For Optics of electronics assumes that even in the event the conduit penetrations are perfectly sealed, the conduits remain likely to contain moisture. Underground conduit often is left unsealed during construction (allowing moisture accumulation), and conduit runs can potentially have multiple points where moisture can enter. Conduit with Moisture Control Cabinets can transfer water vapor in to a sealed enclosure. Typically, when electronics are energized, heat is generated and also the air inside the enclosure can hold even more moisture than ambient conditions, meaning water vapor is a lesser problem. The situation takes place when the enclosure temperature drops (due to the equipment being de-energized, cooler nighttime temperatures, cooler weather conditions, etc.) and also the temperature inside xakleh enclosure drops underneath the dew point, causing condensation.
Expanding polyurethane foam sealant (Fig. 4) provides an excellent way of sealing around conduit cabling: It’s been found to be preferable over silicone, primarily because caulking guns used in combination with silicone are difficult to insert far enough into the conduit to attain a powerful seal. A growing foam nozzle attachment can be inserted further in to the conduit to generate a highly effective seal across the cabling.