Control power source apparatus

A control power source apparatus comprising:

• a power source board (2) accommodated in an electric component box (1) made of an incombustible material;
• a first power source unit (PS1) provided at the power source board (2) and comprising a first current limiting circuit configured to enable the first power source unit (PS1) to supply electric power that is limited by an upper limit of a predetermined value;
• a second power source unit (PS2) provided at the power source board (2) and comprising a second current limiting circuit configured to enable the second power source unit (PS2) to supply electric power that is limited by an upper limit of a predetermined value;
• a step-down circuit (3) disposed outside the electric component box (1) and connected to the first current limiting circuit or the second current limiting circuit, the step-down circuit being configured to step down voltage outputted from the electric component box (1);
• a first load circuit (L1) provided outside the electric component box (1) and configured to be supplied with electric power from the first power source unit (PS1);
• and
• a second load circuit (L2) provided outside the electric component box (1) so as to be electrically independent from the first load circuit (L1), and configured to be supplied with electric power from the second power source unit (PS2).