PoE Midspan With Switch Tested

Author: John Scanlan, Published on Mar 23, 2016

Both PoE switches and midspans generally provide power to network devices.

One question that is regularly raised in IPVM classes is whether combining the two will cause problems, e.g., the camera to be fried.

***** * *** ****** **** * ******* ******** *** ***** when ******* ********* ** ********** **** ***** (**** ***** **, PTZs, ******* / *******) *** ****, ******* **** **** *** 15 ** ** ***** ******* ******** ******.

** **** **** ********** **** **** *********** ** *** * risk *** ** **** ********, ** ****** ****. ** **** report, ** ***** *** ******** ********* ******.

PoE *** ************ **********PoE is commonly used to power IP cameras, eliminating a separate cable and supply for power. In most cases, a PoE switch combines both switching and power supply into a single unit. However, for older non-PoE switches or where PoE demand outstrips supply, a separate unit called a midspan is often used. More: ***: ****** **. ************* ***** *** ** ***** ************.

Test *********

** **** ****, ** **** ****** ***** ******,********* *******,***** ***** ** ******, & ***** ******** ***** *****. *******, ** ********** **** **** ** ******* ***** ***********, ******* ** **** report.

Measuring *****

** *** * **** ******* ***** ***** *** *** ****. Here ** * ***** ** *** ** ***** **** ** cameras:

Midspans ****** **** ******

** *** ***** *****, ** **** * ****** ********* ** a ******* ******** *** *** ******. ******* *** ****** **** also ***** ********** ** **** *****, *** ****** ********* ***** no ***** ***** **** ** *** *******. **** *** ****** is ********* *** *****.

** *** ***** *****, ** **** *** ***** ****** ******* the ****** *** *******. *** ******* ** ***** *** **** device ********* *****. ****** **** ***** ** *** ****** **** the ****** ** *** *******, **** *** ***** ******* *. However, *** ********* ** ***** *******/******* ** ********.

Camera ******* ** ******

**** ** ** ******* ** **** *** **** ****** ******* directly ** *** *** ******. ***** ************ *** ******* ** those **** ******* ******* *** ******.

Explaining *******: ** ******* *****

** ** ***** *** *******:

  • *** ****** ******** ********* ** *** ****** ** *** **** device ********* ***** ** ******.
  • **** *** ******* ******, *** ****** ** *** ********* ***** to *** ****** *** ** *** ******** ******* ***** ********* to ****.
  • **** *** ****** ** ********* *** ***** ** **** ********.

*** ****** **** ** *** **** ** *** ** *** PoE *********** ******* ******* ****** *** ******. ** *** *****, the ****** ********** ****** ** ********** *** **** *** ******* injector, ***** ***** ** *****. *******, *** ******* ******** **** not ******* *** **** *** ******, ** ** ***** ** sent. ** **** ***, ****** ** ********* *** ** ***** is ********* ** *** ******* ****** ************ *********.

PoE ***** ******* ****

*** ********** *****-****-******** *************,**** ***.***, ******** ***** **** ***** *********** ******* ** ***** ** in * ******* ***** ** *******. **** ***** * *** switch *** * ******* ******** ********, *** ****** ****** **** only **** **** *** *** *****.

*** ***.*** '***', ** ******* ******* **** *******, **** ******** themselves ** ********* *** **** **** *** *******. **** *********** process ******* ***** *** ***** ******, ** '***' **** * switch ** ******* ***** *** ******* ****** ** *** ****, looking *** * ************** ********* ** ********. ** ** ********, or ** ********* ******** ** ********, ** ***** ** ****.

** *** **** ** *** ******* *** ******, ** ******* is **** *** ******** ** *** *******, ** *** ****** sends ** *********** ******** *****.

Comments (2)

Nice work, John!

On a more basic level I would mention that there is really no danger of frying a camera because of double POE for the simple reason that even if both the midspan and the endspan were to both (mistskenly) provide power, this wouldn't do anything to the camera as it is just power in parallel.

So the same voltage, though double the potential max amps. But since same resistance it just draws the same.

Here's a worst case scenario to show what I mean: Here I have taken two passive POE sources and put one on the 1236 and the other on the 4578, by using to injector cables and a custom keystone.

So this means that they are both always on. I was hoping that the byte brothers would show this as 12345678 POE, but instead it just alternates between 1236 and 4578 every seconc or so.

In any event the camera works fine since there is no increase in volts. I have the closeups if you need want to see anymore.

Looks goods! I was also hopeful that power panel would test / display 12345678 at the same time.

Login to read this IPVM report.
Why do I need to log in?
IPVM conducts unique testing and research funded by member's payments enabling us to offer the most independent, accurate and in-depth information.

Related Reports on Power

Amazon Ring Spotlight Cam Tested on Sep 17, 2018
Amazon's Ring has released their latest camera entry, the Spotlight Cam, which we bought and tested in our Consumer IP Camera Analytics...
VMS Export Shootout - Avigilon, Dahua, Exacq, Genetec, Hikvision, Milestone on Sep 13, 2018
When crimes, accidents or problems occur, exporting video from one's video surveillance system is critical to proving incidents. But who does it...
Exit Devices For Access Control Tutorial on Aug 28, 2018
Exit Devices, also called 'Panic Bars' or 'Crash Bars' are required by safety codes the world over, and become integral parts of electronic access...
Backup Power for Large Security Systems Tutorial on Aug 24, 2018
Choosing the right backup power system depends on system size. While small and medium systems greatly benefit from using UPS battery backup...
SNMP / Network Monitoring For Surveillance 2018 on Aug 21, 2018
Surveillance systems typically rely on the the VMS to report issues, but this most often just means knowing a camera is "down" with no warning or...
Axis First IR PTZ Tested (Q6125-LE) on Aug 21, 2018
Axis is very late in releasing IR PTZs. While competitors such as Hikvision and Dahua have offered them for years, Axis has just released their...
Backup Power For Maglocks Guide on Aug 20, 2018
When the main power fails, many believe maglocks must leave doors unlocked. However, battery backed up maglocks are allowed according to IBC /...
Backboxes for Video Surveillance Tutorial on Aug 15, 2018
Backboxes are a necessity in surveillance, whether for managing cable whips, recessing cameras, adding wireless radios. But it can be confusing to...
Installing Dome Cameras Indoors Guide on Jul 16, 2018
IPVM is producing the definitive series on installing surveillance cameras. This entry covers one of the most common scenarios - installing dome...
Installation Hardware for Video Surveillance - Indoor Fasteners on Jun 22, 2018
As part of our Installation for Video Surveillance series, in this note, we cover drywall anchors. A key part of installing security hardware is...

Most Recent Industry Reports

Genetec Takes Aim At 'Untrustworthy' 'Foreign Government-Owned Vendors' on Sep 24, 2018
Genetec is taking aim at 'untrustworthy' 'foreign government-owned vendors'. This is not a new theme for Genetec as nearly 2 years ago, Genetec...
4MP Camera Shootout - Axis, Dahua, DW, Hanwha, Hikvision, Uniview, Vivotek on Sep 24, 2018
4MP usage continues to climb, especially for low cost fixed lens models. To see who was best, we bought and tested seven 4MP models from Axis,...
Alexa Guard Expands Amazon's Security Offerings, Boosts ADT's Stock on Sep 21, 2018
Amazon is expanding their security offerings yet again, this time with Alexa Guard that delivers security audio analytics and a virtual "Fake...
UTC, Owner of Lenel, Acquires S2 on Sep 20, 2018
UTC now owns two of the biggest access control providers, one of integrator's most hated access control platforms, Lenel, and one of their...
BluePoint Aims To Bring Life-Safety Mind-Set To Police Pull Stations on Sep 20, 2018
Fire alarm pull stations are commonplace but police ones are not. A self-funded startup, BluePoint Alert Solutions is aiming to make police pull...
SIA Plays Dumb On OEMs And Hikua Ban on Sep 20, 2018
OEMs widely pretend to be 'manufacturers', deceiving their customers and putting them at risk for cybersecurity attacks and, soon, violation of US...
Axis Vs. Hikvision IR PTZ Shootout on Sep 20, 2018
Hikvision has their high-end dual-sensor DarkfighterX. Axis has their high-end concealed IR Q6125-LE. Which is better? We bought both and tested...
Avigilon Announces AI-Powered H5 Camera Development on Sep 19, 2018
Avigilon will be showcasing "next-generation AI" at next week's ASIS GSX. In an atypical move, the company is not actually releasing these...
Favorite Request-to-Exit (RTE) Manufacturers 2018 on Sep 19, 2018
Request To Exit devices like motion sensors and lock releasing push-buttons are a part of almost every access install, but who makes the equipment...
25% China Tariffs Finalized For 2019, 10% Start Now, Includes Select Video Surveillance on Sep 18, 2018
A surprise move: In July, when the most recent tariff round was first announced, the tariffs were only scheduled for 10%. However, now, the US...

The world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally. Dedicated to independent and objective information, we uniquely refuse any and all advertisements, sponsorship and consulting from manufacturers.

About | FAQ | Contact