To prevent lighting to prevent a fire even if an incandescent lamp generating quantity of light equal to a fluorescent lamp is inserted in a lamp holder of a compact self-ballasted fluorescent lamp lighting system.
When a regular compact self-ballasted fluorescent lamp is inserted in a lamp holder 6, since voltage drop in resistance R2 is small, a transistor Q2 does not conduct electricity, the contact of a relay 104 keeps a closed state, and the lamp continues lighting. When a lamp of large power consumption is inserted in the lamp holder 6, voltage drop in the resistance R2 becomes large, the transistor Q2 is made conductive, and the contact of the relay 104 opens. Thereby, the lamp puts out lights, but a photodiode D6 emits light, a phototransistor Q1 is made conductive, and supplies base current to the transistor Q2. The transistor Q2 continues a conductive state and the relay 104 keeps an on state of the contact. When the lamp of large power consumption is removed, the photodiode D6 puts out lights, the transistor Q2 is turned off, and the contact of the relay 104 is closed.
SATO NOBUMICHI