Which Ethernet pins conduct power for passive power over Ethernet (PoE)?

Which Ethernet pins conduct power for passive power over Ethernet (PoE)?

• 2, 3, 6, and 7
• 1, 3, 5, and 8
• 4, 5, 7, and 8
• 4, 6, 7, and 8 

 

EXPLANATION

Two pairs are used for data transfer. The two spare pairs that are not used for data transfer are used to carry power.
So the positive voltage is applied to pins 4 and 5 of the Ethernet cable. The negative voltage is applied to pins 7 and 8.

SOURCE

POE device-specific pinouts:

STANDARD	SOURCE									LOAD		REMARKS
		Ethernet RJ-45 connector pin number
	Source Voltage	1	2	3	4	5	6	7	8	Load Voltage	DC Load Connector
IEEE 802.3af using data pairs	48 V DC, protected	RX, DC+	RX, DC+	TX, DC-	spare	spare	TX, DC-	spare	spare	(embedded)		Industry Standard for active PoE
IEEE 802.3af using spare pairs	48 V DC, protected	RX	RX	TX	DC+	DC+	TX	DC-	DC-	(embedded)		Industry Standard for passive PoE
Intel, Symbol, Orinoco	Usually 12 or 24 V DC	RX	RX	TX	DC+	DC+	TX	DC-	DC-	(embedded)		Most Brands of PoE
Cisco (OLD old standard)	48 V DC	RX	RX	TX	DC-	DC-	TX	DC+	DC+	(embedded)		Older Cisco polarity is REVERSED
Cisco (NEW old standard)	48 V DC	RX	RX	TX	DC+	DC+	TX	DC-	DC-	(embedded)		New Cisco is IEEE compliant
Cisco   (very unusual)	28 V DC	DC+	DC-	TX	n.c.	n.c.	TX	RX	RX	(embedded)		Seen on Cisco 7936 conference station, also worked with Polycom SoundStation IP 4000 with 19V source power
D-Link (Adapter)	48 V DC	RX	RX	TX	DC+	DC+	TX	DC-	DC-	5VDC @ 2.5A or 12VDC @ 1A	DC coaxial 5.5/2.5mm	D-Link PoE Adapter for non-PoE products.
Apple MacIntosh AirPort PoE, Extreme	48 V DC	RX	RX	TX	DC?	DC??	TX	DC??	DC??	Converted to ???	DC coaxial (???)	Mac Polarity Unknown
HyperLink	Many DC Voltages Available	RX	RX	TX	DC+	DC+	TX	DC-	DC-	same as input	DC coaxial and others available	Variety of Options Available to Fit Most Brands of PoE
NYC Wireless Roll Your Own	12 or 24 or 48 V DC	RX	RX	TX	DC+	DC+	TX	DC-	DC-	same as input	DC coaxial or as reqd	New York City Wireless PoE
3Com AirConnect	24 V DC	RX	RX	TX	spare	spare	TX	DC+	DC-			3Com AirConnect wireless access points
Alvarion VL	55 Vdc	RX	RX	TX	DC+	DC-	TX	DC+	DC-
TP-link TL-SF1008P		DC-	DC-	DC+					DC+
Polycom IP500 / 501	12V DC	RX	RX	TX	DC-	DC-	TX	DC+	DC+			The only difference between regular PoE injectors and the Polycom one is the inverted polarity.