Common wiring techniques used for electrical controls and safety devices in HVAC systems include series wiring, parallel wiring, and ladder wiring. Series wiring involves connecting devices in a single circuit, where the current flows through each device in sequence. Parallel wiring involves connecting devices between the same two points, allowing multiple devices to operate independently. Ladder wiring involves arranging devices in a ladder-like configuration, with each device connected to the previous one. The choice of wiring technique depends on the specific application, system requirements, and device characteristics.