Abstract: A lighting device according to an embodiment includes a socket unit, a light emitting unit, and a lid unit. The light emitting unit is provided in an accommodation unit of the socket unit, and includes a light emitting element. The lid unit closes the accommodation unit of the socket unit, and is formed with an opening portion which causes light radiated from the light emitting element to pass through. An end face of the light emitting unit on the opening portion side overlaps with the opening portion in the thickness direction of the lid unit, and is located on the light emitting unit side rather than an end face of the lid unit on a side opposite to the light emitting unit side.

Abstract: A retrofit kit for a lay-in troffer LED luminaire comprising two sets of connecting beams, with a first set being arranged in a parallel orientation and a second set of connecting beams oriented in a perpendicular manner with respect to each of the first set of beams. Each set of connecting beams are engaged to connected to each other by means of multiple coupling retainers and clamping hooks matched with each other to form a quadrangular bracket capable of containing the troffer. Compressible and extendable fastening means are further placed at the lateral sides of the troffer. And the troffer is connected to the ceiling through the allocation with the bracket by making fastening means aligned with the connecting holes on the first or the second sets of connecting beams that receive the fastening means.