PoE Power Problems

By: Ethan Ace, Published on May 23, 2012

One of the nastiest and most difficult to identify problems is insufficient PoE power. One minutes, things may be working fine. The next, the system seems to be going haywire, with little indication why. In this update, we overview the potential causes for these issues, and how to troubleshoot them.

Overview

Actual PoE power consumption of IP cameras may be difficult to determine accurately. Manufacturers often list power consumption in wattage on data sheets, but without external equipment, there is no way to verify this. Additionally, most do not show PoE class, which may be important in troubleshooting. PoE power consumption is divided into four classes, grouped by wattage, ranging from 0.44W to 30W. The class required by a given device is negotiated with the power source, either a switch or a midspan, upon connection.

Under normal circumstances, devices should request only the power they need. However, if a camera is malfunctioning, it may negotiate the wrong class of power, or may draw more power than was negotiated, both issues which can cause significant problems.

Where Issues Arise

Most commonly, lack of sufficient total power is the root cause of PoE issues. Many switches, including most low-cost/small business models, provide only 7.5W PoE on all ports, but support up to 15W on individual ports. In the case of a 24-port switch, for example, total available power is generally between 180-190W.

However, consumption of 9W or more is not uncommon among popular HD camera models, such as the Axis P13 [link no longer available] and Q series [link no longer available], or Sony's CH140. In this case, 18-20 cameras may work fine, as the switch's total power budget is not exceeded, but additional cameras will begin to cause unexpected issues.

Troubleshooting Issues

Plugging in one camera too many typically does not simply shut down the switch, but causes intermittent issues. Since camera power consumption varies slightly while in use, cameras may work fine for a period of time, until total consumption exceeds power budget. This may occur at seemingly random times, day or night, and result in any of the cameras being lost, making the issue extremely difficult to pinpoint.

The simplest means for PoE troubleshooting is to use a managed switch or PoE midspan. Actual power consumption of each port may be viewed in real-time via the management interface, so overages on specific ports are simpler to detect. This image displays the management interface of a PowerDsine managed midspan, displaying per-port and total consumption figures:

Get Notified of Video Surveillance Breaking News
Get Notified of Video Surveillance Breaking News

PoE Testers

External testers must be used to troubleshoot PoE issues if unmanaged switches are used. These devices are connected inline between the camera and switch, and used to check actual consumption of individual ports. The Byte Brothers PoE Power Panel [link no longer available] (~$160 online) is one expensive means of testing this, though more expensive network analyzers, such as the Fluke NetTool [link no longer available] (~$2,500 online) provide this feature in addition to other connectivity tests.

Solutions

When using managed switches, limiting the per-port power of certain ports may reduce issues. For example, in some cases, due to poor PoE implementation or malfunction, a camera may consume more power than it actually needs. Limiting this camera to only 7.5W power output may alleviate the issue system-wide. In other cases, however, the camera will not function on this reduced consumption, requiring either an individual midspan be used, or the entire switch replaced.

When using unmanaged switches, little can be done. Without a management utility, no power limits can be set. In this case, the switch must be replaced with a managed model, or a PoE midspan added.

Full PoE Switches

Replacing switches with higher PoE budget models is not an inexpensive proposition, however. In most cases, among the major manufacturers, at least, 15W PoE capability on all ports requires moving to enterprise level switches with a much higher price. As an example, Cisco's 300 series managed switches (7.5W per port, 180W total) sell for about $500 online. Moving to the Catalyst 2960 to gain full PoE capability (15W per port, 360W total) is a price increase of about $600 (~$1,100 online).

The second solution is to supply PoE via a managed midspan, which allow the same power management and monitoring features of managed switches. 24-port midspans can be found online for $500-700. Based on these prices, a managed midspan combined with an unmanaged switch or low-cost non-PoE managed switch (~$200 online) will likely cost less than using enterprise-level switches. Additionally, an external midspan may be replaced if power needs increase, to current HiPoE and higher levels in the future.

1 report cite this report:

PoE for IP Video Surveillance Guide on Mar 08, 2018
This guide provides comprehensive explanations of the elements in selecting and using Power Over Ethernet with IP cameras. Inside this report we...
Comments : Members only. Login. or Join.

Related Reports

Last Chance - Spring 2020 IP Networking Course - Register Now on May 06, 2020
This is the last chance to register for the only networking course designed specifically for video surveillance professionals, taught...
Converged vs Dedicated Networks For Surveillance Tutorial on Feb 12, 2020
Use the existing network or deploy a new one? This is a critical choice in designing video surveillance systems. Though 'convergence' was a big...
BICSI For IP Video Surveillance Guide on Feb 11, 2020
Spend enough time around networks and eventually someone will mention BICSI, the oft-referenced but only vaguely known standards body prevalent in...
Network Cabling for Video Surveillance on Jan 15, 2020
In this guide, we explain the fundamentals of network cabling for video surveillance networks, how they should be installed, and the differences in...
Horizontal Cabling for Video Surveillance Guide on Jan 03, 2020
There are a few options when it comes to professionally installing horizontal cabling for video surveillance networks. The three options examined...
Altronix Claims Tango 'Eliminates Electricians' on Oct 15, 2019
Power supply provider Altronix claims its new Tango power supply 'eliminates the need for an electrician, dedicated conduit and wire runs'. In...
'Bunker Busting' Wireless Access Startup: Sure-Fi Profile on Oct 03, 2019
An access startup is claiming its 'bunker busting' wireless Wiegand radios can punch through 'any obstruction'. We examine their offering,...
Siklu $400 Compact 60GHz Radio on Jul 24, 2019
Siklu first entered the video surveillance market with a $6,000 per link solution, is now aiming down market with their newest 60GHz wireless...
Dahua ePoE Long Distance UTP / Coax Tested on May 03, 2019
Dahua's Enhanced PoE (ePoE) line is claiming extended video and power transmission over 600m without repeaters, with devices interchangeable via...
Cambium Wireless Video Surveillance Profile on Mar 27, 2019
Cambium Networks, spun out of Motorola Solutions in 2011, says "outdoor durable radios are in their DNA" and they are targeting video surveillance...

Most Recent Industry Reports

Wyze Raises $10 Million And Seeks Services Expansion on May 27, 2020
Wyze has raised $10 million, the company's first disclosed raise since the $20 million announced at the beginning of 2019. Inside this note,...
Startup Videoloft Presents Cloud Storage on May 27, 2020
Videoloft presented offsite cloud storage at the May 2020 IPVM Startups show. A 30-minute video from Videoloft including IPVM...
Directory of 250+ Fever Camera News Reports Globally on May 27, 2020
This global directory tracks 250+ articles about thermal cameras used to detect fevers in response to the coronavirus pandemic. Articles are...
Integrators Rising Against Coronavirus on May 27, 2020
IPVM integrator statistics make it clear - Coronavirus's impact on business is lessening and many are anticipating even better news in weeks...
Netposa Stock Surges 46% After US Human Rights Abuse Sanctions on May 27, 2020
Last Friday, the US government announced it would sanction PRC video management provider NetPosa for being "complicit in human rights violations...
LILIN Presents NDAA-Compliant P2 Cameras on May 26, 2020
Merit LILIN presented its NDAA-compliant P2 camera series at the April 2020 IPVM New Products show. Inside this report: A 30-minute video...
ZKTeco Body Temperature and Mask Detection Reader Tested on May 26, 2020
While dedicated fever cameras emerged first, now tablet/kiosk fever detectors are ramping up. China's ZKTeco has been aggressively promoting such...
IDIS Presents 12MP IR Panoramic Fisheye on May 26, 2020
IDIS presented its 12MP IR panoramic fisheye camera at the April 2020 IPVM New Products show. Inside this report: A 30-minute video from...
FDA Defines Correct Operation of "Fever Cameras" on May 26, 2020
The US FDA has now defined the correct operation of "Thermal Imaging Systems", colloquially known as "fever cameras". Many in video...
OnSSI Founders Return, Start Corsight on May 25, 2020
The OnSSI founders are back, less than 2 years after selling OnSSI to Qognify, they have returned to Corsight, a spin-out of an Israeli AI...