Grumpy_Mike:
That is very silly. If the led string gets to be an open circuit what is the danger? If it is below 50V then it is safe. Under what circumstances will 5V be safe when 12V is not? Remember a child’s electric train set has extensive exposed rails with 12V on them and no one (yet in this safety mad era ) thinks they are not safe.
The constant voltage driver [or "constant voltage" setting] is to accommodate [cheaper] LED strings that are meant to be constant voltage driven (i.e. they have a resistor in series with the LEDs -- and often the "set" is composed of one or more parallel strings of resistor terminated, series connected LEDs, with the advantage being that more LEDs can be powered by one, lower voltage driver). Which, I agree, is a less reliable way of driving LEDs -- especially higher powered LEDs.