Can you use standard RJ45 network cable with a PoE installation?
This question was answered by Akshay Thakur, business development manager of the industries and IoT product group at Cisco.
In general, yes, but this depends on the Powering Device (PD) and network architecture. There are recommendations to ensure proper function of the PD.
As defined in IEEE 802.3af and IEEE 802.3at, PoE delivers electrical power over two pairs out of the four twisted pairs of cable in Class D (also known as Cat5e) or better (Cat6, 6a, 7, etc), cabling as specified in ISO/IEC 11801:1995.
Power Sourcing Equipment (PSE) uses only signal pairs, the pairs 1, 2 and 3, 6, to transport power from the PSE to the PD and leaves the spare pairs, the pairs 4, 5 and 7, 8, idle. This architecture can deliver up to 30W per port.
Cisco Universal Power Over Ethernet (UPOE) uses the same cabling standard as PoE. Instead of delivering power over two twisted pairs, it provides the capability to source up to 60W of power by using all the four pairs of standard Ethernet cabling (Cat5e, Cat6, Cat6a, or better).