You may need to replace an outlet if its not holding plugs securely, showing burn marks, making crackling sounds, or has stopped providing power. A switch might need replacing if it feels warm to the touch, doesnt reliably control power anymore (flickering lights), makes buzzing noises, or shows visible damage. Fixtures should be replaced if theyre damaged beyond repair (cracked housing or broken sockets), have persistent electrical issues despite bulb replacements or wiring checks, or for aesthetic upgrades.