High humidity in a cabinet produces condensation and corrosion, which often leads to creep currents, flash-over, contact problems, etc.
The difference in temperature between night and day can often be sufficient for condensation to form. To prevent this, besides a thermostat that starts a heater before the set minimum temperature is reached, a hygrostat should also be mounted that starts the heater/fan if the humidity exceeds a set value. MFR012 has a change-over contact and can even be used to control air humidifiers if the air becomes too dry.
