Red Seal Plumbing Practice Exam

The correct connection for the 120 Volt power supply for a humidifier is by connecting to the HTG ACC and COM contacts on the electronic control board. Option A and D are incorrect because C and Y are typically used for the cooling function of a thermostat, not for powering a humidifier. Option B is incorrect because R and C are typically used for powering the heating function of a thermostat, not specifically for a humidifier. It is important to note that different control boards and HVAC systems may have different configurations, so it's always best to refer to the manufacturer's instructions or consult a professional if unsure.