The hand held, battery-operated tool uses a voltage detector to identify the broken circuit so you can replace bad bulbs or, if needed, send a pulse of electricity through the circuit to fix the shunt in the bulb socket.
The website demonstration video suggests it only takes 10 seconds solve the problem.
While the actual repairs can be completed quickly, our tests found it takes several minutes to get a hang of how the tool works.
After reading the instructions several times and getting a feel for the proper angles to hold the tool while it's activated, we found the Light Keeper Pro did work. We quickly found the burnt out bulb in two light sets, and repaired the circuit in two others.
On the down side, I found the bulb removal feature to be something of a dud. Some consumers report difficulty using the bulb tester feature, saying they found it awkward.
Light Keeper Pro is not designed to work with LED lights or lights attached to a control box. It sells at hardware and discount stores just about everywhere for $20 or less.