Security Glossary

What Is PoE — Power over Ethernet?

PoE (Power over Ethernet) lets a single network cable carry both data and electrical power to a device — eliminating the need for a separate power outlet at each camera location. For NYC installs in tight brownstone walls, co-op ceilings, and commercial drop-tile runs, this one cable instead of two makes a significant practical difference.

IEEE 802.3af / 802.3at Standard Up to 100m per cable run Works with IP cameras & access control
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What It Is

Understanding PoE — Power over Ethernet

Power over Ethernet (PoE) is a technology that transmits electrical power alongside data through a standard Ethernet (Cat5e, Cat6, or Cat6A) cable. Instead of running a data cable to your camera and then finding a nearby electrical outlet or hiring an electrician to add one, a PoE-capable switch or injector at the other end of the cable handles both jobs simultaneously — one cable, one termination, one job done.

Technically, the power is delivered over the unused wire pairs (or sometimes the same pairs as data, depending on the standard) in the Ethernet cable. The device that supplies the power is called a PSE (Power Sourcing Equipment) — typically a PoE switch or a standalone PoE injector. The device receiving power is called a PD (Powered Device) — your IP camera, door controller, or intercom. The IEEE 802.3af standard delivers up to 15.4W per port; 802.3at (PoE+) doubles that to 30W; and 802.3bt (PoE++) goes up to 90W for more demanding devices like PTZ cameras or multi-door access controllers.

In New York City, PoE matters most because of what the buildings here are made of. Brownstones have plaster walls and narrow chases. Co-ops often restrict where and how electrical work can be done — sometimes requiring board approval or a licensed electrician for any new outlet. With PoE, the camera's power comes from the low-voltage cable run back to your IT closet or equipment rack, which typically falls under low-voltage work rather than electrical, streamlining the DOB permit picture and avoiding the need to coordinate with a separate electrician on most jobs.

If your property already has a wired network infrastructure, PoE cameras are almost always the right choice over Wi-Fi cameras — more reliable, higher quality video, and simpler to manage at scale. Wi-Fi cameras make sense for temporary setups or locations where no cable run is feasible, but for any permanent installation in a NYC building, PoE is the professional standard.

Key Facts

What You Should Know About PoE

01

Cable Distance Limit: 100 Meters

PoE follows the same 100-meter (328 ft) maximum run length as standard Ethernet. For larger buildings — a 10-story co-op or a multi-floor commercial space — this means your PoE switch needs to be located close enough to each camera. On bigger jobs, intermediate IDF closets or PoE extenders are used to bridge the distance.

02

PoE Standards: Match Your Device to Your Switch

Not all PoE is equal. Standard PoE (802.3af) handles basic fixed cameras. PoE+ (802.3at) is needed for cameras with built-in heaters, IR illuminators, or two-way audio. PoE++ (802.3bt) is required for high-power PTZ cameras or multi-door access control panels. Mismatching a high-draw device with an underpowered switch port causes unreliable operation or no power at all.

03

Total Switch Budget Matters

A PoE switch has a total power budget (e.g., 65W, 130W, 250W) shared across all its ports. A 16-port switch with a 130W budget can't run 16 cameras that each draw 15W simultaneously. When sizing a system, installers calculate the total draw across all connected devices and choose a switch with adequate headroom — typically 20–25% more than the calculated load.

04

Low-Voltage Work — But the Switch Needs Power

The cable runs and camera terminations are low-voltage work, which Seneca handles under its NYC low-voltage license. However, the PoE switch itself plugs into a standard electrical outlet or is fed by a UPS (uninterruptible power supply). That outlet needs to exist in your equipment location — worth confirming before install day, especially in older NYC buildings where closet outlets are scarce.

Common Questions

FAQ: PoE — Power over Ethernet

Only if your existing switch has PoE-capable ports. Most basic office or home routers and switches do not supply PoE. You can check your switch's model number against the spec sheet. If it doesn't support PoE, the two options are: replace the switch with a PoE switch, or add a standalone PoE injector (a small passthrough device) on each camera run. For multi-camera installs, a dedicated PoE NVR or managed PoE switch is almost always the cleaner solution.
In most cases, no electrical work is needed at the camera location itself — that's the main advantage. The only electrical requirement is a standard outlet where your PoE switch or NVR is installed, typically a utility closet, server rack, or equipment cabinet. If that location already has an outlet, no electrician is needed for the camera installation. This is especially useful in co-ops and condos where board approvals for electrical modifications can slow a project down significantly.
Cat5e is the minimum and technically supports PoE, but for new installs we run Cat6 or Cat6A. The heavier gauge conductors in Cat6/6A handle PoE power delivery more efficiently, generate less heat over the run, and give you headroom for higher-bandwidth cameras now or in the future. In conduit runs — common in NYC commercial spaces and newer residential buildings — Cat6A in-conduit is the standard we recommend.
PoE cameras go offline when their switch loses power — which is exactly why we recommend connecting your PoE switch and NVR to a UPS (Uninterruptible Power Supply). A properly sized UPS keeps your cameras and recorder running for 30–60 minutes or more during a power outage, which covers most short outages and gives battery backup during the moments when you may need surveillance most. This is a standard part of any Seneca camera system design.
Yes — PoE powers a wide range of low-voltage devices beyond cameras. Common examples in NYC commercial and residential installs include: IP intercoms and video doorbells, access control card readers, VoIP desk phones, wireless access points (WAPs), and network-connected speakers. If a device needs both a data connection and power and doesn't draw more than 90W, PoE is almost always a viable delivery method.

Related Terms

Terms That Go Hand in Hand with PoE

PoE doesn't operate in isolation — understanding these related terms will give you a complete picture of how a wired IP camera system comes together.

IP Camera NVR (Network Video Recorder) Cat6 vs Cat6A

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Seneca Security designs and installs PoE camera systems throughout New York City — from single-unit brownstones to multi-floor commercial buildings. We handle the cable runs, switch sizing, and NVR configuration so everything works from day one.

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