Which cable type may not be used as a power-limited riser cable?

The correct answer is the option that identifies the cable type which may not be used as a power-limited riser cable, which is CL3. Power-limited riser cables are designed for vertical spaces and must comply with specific installation requirements, including flammability and low-power transmission thresholds.

CL3 cables are typically utilized for communication and data transmission applications where a higher level of performance is required compared to CL2 cables. However, they are not categorized for use in power-limited riser applications, which restrict the amount of power that can be transmitted through them for safety and regulatory reasons.

In contrast, CL2 cables are allowed for power-limited uses, as they are designed for installations that require lower ratings of electrical power, enhancing safety in riser applications. CL4 and CL5 cables also address specific power-limited installations and provide suitable performance characteristics for riser applications.

Thus, recognizing the limitations of cable categories in relation to power-limited riser applications helps ensure compliance with safety standards in building installations.