PoE, PoE+ and PoE++ Explained for UAE Office Networks
Three names, three IEEE standards. PoE is 802.3af and allocates up to 15.4 W at the switch port. PoE+ is 802.3at and allocates up to 30 W. PoE++ is 802.3bt, which allocates up to 60 W as a Type 3 port and up to 90 W as a Type 4 port by using all four pairs instead of two. IEEE 802.3bt was approved by the standards board on 27 September 2018 and published on 31 January 2019, and its stated purpose is to raise the power available to a device "by utilizing all four pairs in the specified structured wiring plant".
Those numbers are allocations at the port, not the draw of the device plugged into it, and they are not the figure that decides whether your order works. That figure is the switch power budget, and it is the one most quotations get wrong.
The four types in one table
| Type | Standard | Pairs used | Maximum at the port | Classes |
|---|---|---|---|---|
| Type 1 (PoE) | 802.3af | 2 | 15.4 W | 0 to 3 |
| Type 2 (PoE+) | 802.3at | 2 | 30 W | 4 |
| Type 3 (PoE++) | 802.3bt | 4 | 60 W | 5 and 6 |
| Type 4 (PoE++) | 802.3bt | 4 | 90 W | 7 and 8 |
Cisco calls four pair power UPOE, and its Catalyst 9300 documentation describes UPOE sourcing up to 60 W as two lots of 30 W over the signal and spare pairs. Read UPOE on a quotation as Type 3 unless the model is listed as a Type 4 PSE.
Classes are how a switch reserves power
A powered device declares a class when the link comes up, and the switch sets aside that much of its budget. The Cisco IOS XE 17.12 configuration guide for the Catalyst 9300 lists the class allocations as 15.4 W for class 0, 4 W for class 1, 7 W for class 2, 15.4 W for class 3, 30 W for class 4, 45 W for class 5, 60 W for class 6, 75 W for class 7 and 90 W for class 8. Class 0 is the fallback for a device that does not declare, and it costs you a full 15.4 W.
The reservation is the part people miss. A class 4 camera that sits at 11 W all day still holds 30 W of the budget until the switch and the device negotiate something lower over CDP or LLDP. On a switch that grants power only when it has power available, twenty such reservations decide whether the twenty first device comes up at all.
What current hardware actually asks for
Take the Cisco Wireless 9178I, a Wi-Fi 7 access point. Its data sheet, updated on 10 August 2026, gives a maximum of 47 W in quad radio mode on 802.3bt class 6, 25.5 W on 802.3at, and 13.95 W on 802.3af with the radios off. The detail that matters commercially sits next to those numbers: on 802.3at the 2.4 GHz and 5 GHz radios drop from 4x4 to 2x2.
Read that as a purchasing outcome. The access point powers up on a PoE+ switch, monitoring is green, and half the radio capability you paid for is switched off with no alarm anywhere. Six months later the complaint is slow Wi-Fi in the meeting rooms, and the cause is a switch decision made during the fit out. Our note on how many access points a Dubai office floor needs covers the count; this is about feeding them.
Phones sit at the other end. The Cisco Desk Phone 9800 data sheet, updated 25 March 2026, puts the 9841 in class 2 and the 9851, 9861 and 9871 in class 3, and lists the 9841 drawing 1.95 W under PoE with the display off. A floor of phones is a rounding error next to a floor of Wi-Fi 7 access points, a reversal of how most UAE offices were cabled five years ago. Our guide to choosing IP phones for a UAE office covers the voice side.
The budget decides the order, not the port label
The Cisco Catalyst 9200 data sheet, updated 1 September 2026, gives the PoE budget per model. A C9200-24P has 370 W with one power supply and 740 W with two. A C9200-48P has 740 W with one and 1440 W with two. Forty eight ports at 30 W would be 1440 W, so a 48 port PoE+ switch on a single supply can fully load fewer than half its ports.
Work a real floor. Twelve Wireless 9178I access points at 47 W is 564 W. Add twenty four class 3 phones holding 15.4 W each, which is 369.6 W of reservation. That is 933.6 W before a single camera, door controller or display, on a switch that offers 740 W until the second power supply arrives. The quotation looked right because the port count looked right.
One more line in that data sheet is worth the whole exercise: in the Catalyst 9200 family, the C9200CX mGig models are the ones listed for IEEE 802.3bt class 6 and UPOE up to 60 W per port, while the C9200 and C9200L models are listed for 802.3at PoE+ up to 30 W. Four pair power is a different model, not a licence key or a firmware setting. If your device list needs 60 W, that requirement belongs in the switch selection, alongside the uplinks and the stacking. We go through the rest of that selection in how to choose a network switch for a Dubai office, and the switches themselves sit under Cisco and HPE Aruba in our catalogue.
Heat is the part the UAE adds
Power in a copper pair becomes heat, and heat in a bundle does not leave quickly. TIA published TSB-184 in July 2009 to set guidelines for power delivery over balanced twisted pair cabling. The revision project for TSB-184-A was requested on 13 June 2014 specifically to cover four pair PoE and currents up to 1 A per pair, and the revised bulletin arrived in 2017 recommending Category 6A or better cabling for new installations that carry remote power.
The physical limit behind those guidelines is simple. As the IEEE 802.3bt working group material from January 2015 puts it, cables used in commercial premises generally carry a 60 °C temperature rating, and a bundle carrying current settles above the ambient around it. Your margin is 60 °C minus the ambient in the void, minus the rise the bundle generates. In an air conditioned Business Bay office that margin is comfortable. In an unconditioned riser or a ceiling void above a Jebel Ali warehouse in August, nobody has measured it, and an assumption is doing the work.
Equipment ratings tighten the same screw. The Catalyst 9200 series is rated for operation from -5 °C to 45 °C up to 1500 m, and the Wireless 9178I access point for 0 °C to 50 °C. A comms cupboard in a UAE office that loses cooling over a long weekend crosses 45 °C without anyone noticing, and the PoE section is the largest heat source inside that switch. Measuring the cupboard and the riser in August, before the bundles are pulled and the switch is chosen, costs an afternoon. Our note on Cat 6, Cat 6A and fibre in a new Dubai fit out covers the cable decision that follows.
What goes wrong in practice
- The budget runs out quietly. The switch grants power only when it has it, so the failure looks like one access point that will not boot, usually the one added last and furthest from the comms room.
- A Type 3 device is fed by a Type 2 port and runs in reduced mode, as the 9178I does when it drops to 2x2 on 802.3at. Everything reports up.
- An old midspan injector bought for 802.3af gets reused for a four pair device. Two pair injectors cannot deliver Type 3 or Type 4 power no matter what the switch behind them supports.
- Cameras arrive after the budget was signed off. A fixed dome and a pan tilt zoom unit with illuminators are not the same class, and the difference lands on a switch that was sized for phones.
- Bundles are pulled tight through a hot void because the drawing showed cable routes, not current, and nobody re-checks when the PoE load doubles at the next refresh.
A short checklist before you buy
- List every powered device by model, with its class and its data sheet draw. Two numbers per device, not one.
- Total the class reservations rather than the typical draws, and add headroom for devices that arrive after handover.
- Check the budget with one power supply fitted, because that is what ships unless the second one is on the order.
- Confirm the exact model supports the type you need. On the Catalyst 9200 line that means a C9200CX for class 6, not a firmware change on a C9200L.
- Specify Category 6A or better for new runs that will carry power, in line with TSB-184-A from 2017.
- Measure the temperature where the bundles will sit and where the switch will live, in the hottest month you can reach before the order.
Every product in our catalogue is quoted rather than priced, because switch, power supply and access point choices move together and a port count on its own tells us nothing. Send the device list and the floor plan and ask for a quotation. If your existing PoE+ switches are fine for another three years, we will say so.
Cover photo: Cables (IMG 3071-CC) by ESO/F. Reckmann, via Wikimedia Commons (CC BY 4.0).
