Electricians check for faulty wiring with diagnostic tools such as multimeters to measure voltage, current, and resistance in circuits. They also visually inspect wires for signs of damage, such as fraying or discoloration. Electricians also perform continuity tests to ensure proper connections throughout the wiring.

Additionally, they may use thermal imaging cameras to detect overheating in wires, indicating potential faults. By combining these methods, electricians identify and rectify faulty wiring to ensure safe electrical systems in homes.