What must be marked on all cables?

The correct answer involves the requirement for cables to have markings that indicate the type of wire. This is essential for a few reasons. First, the markings help identify the specifications of the wire, such as its voltage rating, insulation type, and suitability for specific applications. Understanding the type of wire is crucial for ensuring proper installation and compliance with electrical codes and safety standards. It aids installers and technicians in selecting the appropriate wire for the job, thus reducing the risk of accidents or malfunctions due to the use of inadequate or unsuitable wiring.

While other factors, such as the manufacturer's name, wire length, and colors of the wires, are important in certain contexts, they do not provide the same critical information regarding the nature and purpose of the cable as the type of wire marking does. These other aspects may also be regulated to an extent, but the indication of wire type is vital in ensuring that safety and performance criteria are met in electrical installations.