Whether the box is inside the wall or surface-mounted on the siding, it should have a watertight weatherproof cover. There are two types of weatherproof cover. The first is the common spring-lid weatherproof cover. This one works just fine until you open it-then it is not watertight. This means you cannot have Christmas tree lights plugged into it or a low-voltage transformer for your sidewalk lights. If the lid is open on a weatherproof cover, rain and snow can get in. What is required for these usages is a cover or lid that is weathertight-while-in-use weatherproof cover, called a safety outlet enclosure or bubble cover.

In-use weatherproof covers or bubble covers come in many different varieties, including shallow and deep. A deep lid will be required if a low voltage transformer is to be used for the outside lights. If the transformer is so large that it can’t fit into the box lid, then plan for the transformer to be plugged into a garage outlet.