Energy Efficient Ethernet: On or Off? (2026 Guide)

Energy Efficient Ethernet (IEEE 802.3az) lets a copper network link drop into a low-power idle state when no traffic is passing, but on a CCTV system that streams video around the clock, the links are rarely idle, so it saves very little. It is normally enabled by default on supporting gigabit switches and negotiated between both ends of the link, and it does not change how much power a PoE camera draws. If you want to cut real power use on a UK install, look at camera wattage, PoE class and switch power budget first, and treat EEE as a minor extra. For a closer look at the power side of PoE kit, see our Accessories: Power range.

What is Energy Efficient Ethernet and what does it do?

Energy Efficient Ethernet (EEE, defined in IEEE 802.3az) lowers a port's power draw while no traffic is crossing the link. Cisco's Green Ethernet documentation says it is enabled globally by default on switches with gigabit-capable ports.

In general terms, EEE works through Low Power Idle signalling on copper BASE-T PHYs. The transmitter drops into a quiet state between bursts of data and wakes when frames are queued. Both link partners must support it and negotiate it, and either end can opt out. It governs the data link only, not the power a PoE switch delivers to a camera.

Related "green" features

Cisco treats EEE as one part of a wider Green Ethernet family, and the other two are easy to confuse with it:

• Energy-detect: puts an inactive port into a low-power state while the link stays administratively up.
• Short-reach: reduces transmit power on short runs, under 30 m for 10G ports and under 50 m for other ports. It applies to RJ45 ports only.

Cisco's introduction describes energy-detect as enabled on all devices, whereas the feature settings I worked from have both options off by default. Check the running configuration on your own model rather than assuming either.

What the source doesn't tell you

The page is switch documentation and gives no wattage saving for any of these features, so don't promise a figure to a client. It also says nothing about how a camera, recorder or PC network adapter handles EEE.

Does EEE save anything on an always-on CCTV network?

Very little. Cameras stream continuously and the NVR ingests continuously, so the links EEE needs to be idle almost never are.

EEE only saves power while a link has no traffic. A camera sending its main stream around the clock never gives the port a quiet moment.

Where idle windows might exist

These are general expectations rather than measurements:

• Uplinks carrying motion-only or low-bitrate sub-stream traffic, where gaps between events are plausible.
• Spare switch ports with nothing connected or nothing talking.
• Monitoring PCs and client machines that are not actively viewing.

The scale problem

A PoE camera's draw is set by its power class and by what it is doing: IR illumination, a lens heater or PTZ motors. Those loads are far larger than whatever a link might save in idle moments. That is reasoning, not a measured result.

If power matters, the lever is the camera. Analog Devices frames power-reducing operating modes in the powered device as the way to address dissipation across large PoE camera estates. Port-level EEE is not the answer it offers.

Which settings actually reduce CCTV power use?

Sizing PoE to real maximum draw and choosing lower-power storage matter more than any single switch setting on a CCTV system. The points below are general installer guidance unless a source is linked.

PoE class and budget sizing

• 802.3af, 802.3at and 802.3bt are the three PoE standards, with at and bt delivering progressively more power per port. Match each camera's class to its datasheet rather than defaulting to the highest.
• Size to the switch's total PoE budget, not per-port headroom: Σ(camera max draw) ≤ switch PoE budget.
• Leave margin for IR at night and for PTZ movement, as both push draw up when the budget is already busiest.

Camera draw

• IR illuminators, heaters and PTZ motors can take a camera to the top of its class. Read the datasheet's maximum figure, not the typical one.
• Power-reducing operating modes in powered devices are a recognised way to cut dissipation across large camera counts, as Analog Devices notes for industrial PoE deployments.

NVR and storage

• Continuous recording means the drives never get the chance to spin down, so drive choice sets a constant load.
• The Western Digital Green 1TB HDD is a lower-power 5400 RPM option, sold for 24/7 recording.
• Flag: the supplier copy contradicts itself. The description says 5400 RPM, but the spec list says 7200 RPM. Confirm the figure on the drive label before relying on it for a power calculation.

Can EEE cause camera compatibility or latency problems?

Usually not: EEE adds only microseconds of wake-up latency, but it is a known suspect when a camera link drops intermittently with no cable fault.

Waking a port from low-power idle takes microseconds in general terms, which is invisible in a video stream. Problems come from poorly implemented PHYs at either end, where the link fails to wake cleanly or renegotiates. Cable quality is a separate fault class, covered in our Cat6 and Cat6a guides.

Symptoms that point at EEE

• The link flaps or renegotiates with no cabling fault.
• The stream drops out briefly at low-bitrate times, such as a static scene at night.
• The NVR shows a camera offline while the link LED stays lit.

Test sequence

1. Rule out the cable and the PoE budget first: re-terminate or swap the run, and check the switch's total and per-port power draw.
2. Disable EEE on the affected switch port. This needs a managed switch with a per-port setting, as many unmanaged units expose no control.
3. Watch the switch link log, or the NVR's event log, for 24-48 hours.
4. Re-enable EEE only if disabling it made no difference, since that shows it was not the cause.

If the dropouts stop with EEE off, leave it off on camera ports.

Related products

Related products from our own range:

• Cat6 vs Ethernet Cable: Speed & Performance Explained — Cat6 Ethernet cables offer significantly faster speeds and better performance than older cables like Cat5e, ideal for high-bandwidth applications.