Which PoE standards specify power over copper cabling and their general purpose?

• A. 802.3az, 802.3ba, 802.11ac
• B. 802.3at only
• C. 802.3af (PoE), 802.3at (PoE+), 802.3bt (PoE++ Type 3 and Type 4) — they specify power over copper cabling.
• D. 802.11n

Answer: (C)

Power over copper cabling is what PoE standards define: delivering DC power over the same Ethernet copper pair that carries data, so devices can be powered without separate power wiring. The PoE family specifies how power is drawn, negotiated, and how much power can be supplied per port. The older PoE standard provides up to about 15 W to devices, which covers smaller devices like basic IP phones. The newer PoE+ standard raises that up to around 30 W, enabling more demanding devices such as higher-end phones or cameras. The most recent PoE++ specifications push power even further, with Type 3 delivering up to 60 W and Type 4 up to 90 W per port, allowing power-hungry equipment like multi-antenna access points and advanced cameras with heaters.

Other items in the list relate to different topics—some refer to energy-saving Ethernet, higher-speed non-PoE standards, or wireless technology—so they don’t specify powering devices over copper cabling.