A cobra arm enclosure device has a hull, a lid, and features for a light pole and a light fixture to attach thereto. The device has a generally rectangular prismatic form that sheds precipitation and ice. It has a top surface upon the lid, a bottom surface upon the hull, a left side, a right side, a front, and a back. The enclosure has an extension that fits into a light fixture. The back of the enclosure has a receiver that fits upon a light pole arm. The enclosure has a width generally greater than that of the cobra arm. Within the invention, it has a storage capacity for electrical components. The invention is an inline enclosure for direct transmission of electrical power and signaling. The invention serves in a system where a central control operates street lighting across a city.