Household electricity travels in closed loops through insulated circuit wires. Red and black wires are hot, which means that they carry the electrical signal, while white and bare wires are neutral and provide a return path back to the electrical source, or the ground. Ceiling fixtures, like all electrical elements, are wired to allow the electricity to perform before following the return path. If insulation or connections fail and the hot wire contacts a neutral inside the fixture, it creates a short circuit that usually is accompanied by electrical arcing and the failure of the fixture.
Check the breaker that controls the circuit if you suspect a short circuit in a ceiling fixture. If there is a short, the breaker will have been tripped. Confirm the short by turning on the light switch, then resetting the breaker. It should trip again immediately. Leave it off.
Look for discoloration of the drywall around the base of the fixture. If you see any, the short is probably in the house wiring and not in the internal wiring of the fixture.
Unscrew the fixture from the ceiling box with a screwdriver and inspect the wiring. You may notice blackened or melted wire insulation and exposed wires at the exact location of the short. You may also find that a wire cap has dropped off the ends of the wires it was covering and that the wires are in contact with the metal base of the lamp, the electrical box or the bare ground wires.
Remove the ceiling fixture if you can't find a problem in the house circuitry. Turn on the light switch and reset the breaker. If the house circuitry is intact, the breaker should stay on. After confirming this, turn off the breaker.
Inspect the fixture for loose internal wiring or worn insulation that has left a wire exposed. Check the solder connections around the base of each of the sockets. If there are exposed wires or one of the solder connections has come loose, you probably will notice a blackened area at which the wires have made contact with each other.
Look inside the sockets. Any blackened area inside one of them is a sign of a defect in the socket that may be causing the short circuit.