In fiber optics, light is transmitted from one end of a thin piece of glass, called a silica, to the other end. Fiber optics are ideal because the light signal is stronger than on a standard metal circuit. Fiber optics are also flexible, which allows them to be installed in narrow and small areas. That makes these lights ideal for swimming pools. Though a quality light source, fiber optics can still experience problems.
Check the fixture at the site of the fiber optic lighting. If the fixture is cloudy, that means it is likely filled with water and the fiber optic lighting will need replacing. If this isn't the problem, proceed to the next step.
Locate the breaker box for the pool lighting system. This will be outside your home, somewhere in the pool area. Check the deck or the side of the home.
Flip the main power supply switch to the "Off" position and open the breaker box panel.
Check the breaker box to see if it is wet. If wet on the inside, that means the protective gasket has broken and needs replacing. If this isn't the problem, turn the breaker power back on and proceed to the next step.
Pull out the breaker itself so you have access to the wiring behind.
Power on your multimeter and set the main dial to "Continuity Test."
Touch the red lead of the multimeter to the white wire running to the breaker and the black lead of the multimeter to the black wire. Wait for the meter to produce a reading. If it does, that means there is continuity and the wiring is okay. If it doesn't produce a reading, the wiring is likely faulty and will need replacing.