A light unit includes: an integrated power (“IP”) board which receives power supply and converts the power supply into a high voltage and a supply voltage; a lamp; and a terminal board (“T board”) which receives the high voltage from the IP board to turn on the lamp, receives the supply voltage from the IP board to transfer the supply voltage to the IP board, in which the IP board transfers the high voltage to the T board after the IP board receives the supply voltage from the T board.