how to tell which xmas light is out

The best way to tell which Christmas light is out is to use a light tester. This device is designed to detect whether a light bulb is working properly by measuring the electrical current flowing through it. If the light tester detects a lack of current, it will indicate that the bulb is out. To use a light tester, simply plug it into an outlet and then touch the metal probes to each end of the light bulb. If the tester lights up, the bulb is working properly. If the tester does not light up, the bulb is out.