UK PoE, PoE+ and PoE++ in brief
PoE vs PoE+ (and PoE++) is a question of how much power one Ethernet port can deliver. All three are IEEE 802.3 standards for Power over Ethernet, which carries DC power and data on the same twisted-pair cable. Each generation raised the power per port so that bigger devices could run from one cable.
PoE is IEEE 802.3af, published in 2003, at about 15 W per port. PoE+ is IEEE 802.3at, from 2009, at about 30 W. PoE++ is the common name for IEEE 802.3bt, from 2018, which adds Type 3 at 60 W and Type 4 at 90 W. The names PoE+ and PoE++ are industry shorthand; the IEEE documents use Type 1 to Type 4.
All three use the same detection handshake, run at around 48 V DC and reach the same 100 m as Ethernet data. What changes is the current, the number of pairs carrying power and the classes a device can ask for.
The three standards compared
Each standard quotes two power figures: what the power sourcing equipment (PSE) puts on the cable, and the lower figure guaranteed at the powered device (PD) after loss in 100 m of cable.
| Name | IEEE standard | Type | Power at PSE | Power at PD | Pairs used | Typical devices |
|---|---|---|---|---|---|---|
| PoE | 802.3af (2003) | Type 1 | 15.4 W | 12.95 W | 2 | Fixed cameras, VoIP phones, sensors |
| PoE+ | 802.3at (2009) | Type 2 | 30 W | 25.5 W | 2 | PTZ cameras, Wi-Fi 6 access points, video phones |
| PoE++ | 802.3bt (2018) | Type 3 | 60 W | 51 W | 2 or 4 | Multi-radio access points, heated cameras, thin clients |
| PoE++ | 802.3bt (2018) | Type 4 | 90 W | About 71 W | 4 | PoE displays, panel PCs, LED lighting |
Our FAQ on how much power PoE delivers breaks the figures down by power class and voltage.
What changed with each generation
The jump from one standard to the next was not just a bigger number.
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802.3af to 802.3at. PoE+ raised the current on each pair from 350 mA to 600 mA and tightened the cable requirement to Cat5e. It added Class 4 and optional power negotiation over LLDP, so a device can request exactly what it needs.
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802.3at to 802.3bt. PoE++ moved power onto all four pairs, which roughly doubles what one cable can carry. It added Classes 5 to 8, autoclass for measured power budgeting, and a lower standby draw so PDs can sleep without losing power.
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Pre-standard 60 W and 90 W. Before 802.3bt, some vendors sold their own four-pair schemes, such as Cisco UPoE. These are often also called PoE++, so check that equipment states 802.3bt compliance.
Mixing PoE, PoE+ and PoE++ equipment
The standards are backward compatible in one direction. A PoE++ or PoE+ source powers an older PoE device without trouble, because the source only supplies the class the device asks for. The other way round is limited: a PoE+ camera on an 802.3af port receives at most 12.95 W, so it may boot with heaters, IR or PTZ motors disabled, or may not start at all.
Four-pair PoE++ also needs all four pairs connected end to end. Older two-pair cabling, or patch leads that only wire four conductors, will limit a Type 3 or Type 4 device. In practice, Cat5e or better throughout is the safe baseline, and Cat6 or Cat6A runs cooler in large bundles carrying 90 W.
Where each standard fits in industrial systems
Industrial sites tend to use all three generations side by side, matched to what each device draws.
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PoE for sensors and fixed cameras. Fixed IP cameras, IO-Link and Ethernet I/O gateways, door controllers and VoIP or intercom stations usually draw well under 13 W.
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PoE+ for vision and wireless. Machine vision cameras with lighting control, PTZ cameras and Wi-Fi 6 access points often need 15 to 25 W, so PoE+ is the usual baseline on new switches.
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PoE++ for displays and outdoor kit. PoE-powered monitors and panel PCs, cameras with heaters for cold sites and multi-radio access points run from Type 3 or Type 4 ports, which removes a separate mains feed at the point of use.
Choosing the right standard for a deployment
Size the standard to the most demanding device on each link, then add headroom for cold starts, heaters and future upgrades. A fixed dome camera fits PoE, a PTZ or multi-sensor camera usually needs PoE+, and a PoE-powered display, panel PC or heated outdoor camera usually needs PoE++. Then check the switch’s total power budget, because a 24-port switch rarely supplies full power to every port at once. Our PoE power budgeting guide works through that sum for a multi-camera system.
On the source side, our industrial PoE switches include 802.3bt models for high-power devices, and our PoE computers power cameras directly from the computer’s own ports. Our guide to industrial Power over Ethernet covers the standards in more depth.
Quick answers on PoE vs PoE+
PoE, PoE+ and PoE++: common questions
Is PoE+ backwards compatible with PoE?
Yes. A PoE+ switch or injector powers 802.3af devices normally, supplying only what each device requests.
Can a PoE+ device run on a standard PoE port?
Sometimes, with limits. It receives at most 12.95 W. Some devices start in a reduced mode; others refuse to boot. Check the device’s minimum power class.
What is PoE++?
IEEE 802.3bt. It delivers up to 60 W (Type 3) or 90 W (Type 4) per port using all four pairs, for devices such as displays, panel PCs and multi-radio access points.
How many watts is PoE+?
30 W at the source, 25.5 W at the device. The difference is the allowance for loss in up to 100 m of cable.
Does PoE++ need special cable?
No special type, but all four pairs. Standard Cat5e or better works. Cat6 or Cat6A is a better choice for large bundles at 90 W because it runs cooler.
We integrate PoE switches and PoE computers matched to each site’s device list and power budget as standard. Send us your camera and device list, and we will specify the PoE standard and budget to match.