In general, a luminaire using a straight tube type fluorescent lamp including G13-type bases each having a pair of lamp pins having a circular shape in cross-section and projecting therefrom at both ends thereof, and sockets for connecting the fluorescent lamp is widely used.
There is also proposed a straight tube type lamp using LED elements. The straight tube type lamps of this type include a straight tube type lamp provided with a cap referred to as an L-shape of a new standard in addition to the straight tube type lamp using the G13-type bases in the same manner in the related art.
The straight tube type lamp provided with the cap referred to as the L-shape of the new standard includes a cap on the power supply side at one end thereof and a cap on the earth side at the other end thereof. The cap on the earth side is formed with one earth pin having a leg portion and a holding portion formed at a distal end of the leg portion and having an oval shape and a diameter larger than the leg portion so as to project therefrom.
A socket on the power supply side and a socket on the earth side specific for such a straight tube type lamp are used. The socket on the earth side is configured to hold the holding portion of the earth pin by means of a terminal in a socket body by inserting the earth pin from a distal end side of the socket body into a predetermined holding position and rotating the earth pin at the holding position.