Welcome, Guest. Please login or register.

Author Topic: Very Basic POE Switch question  (Read 199 times)

0 Members and 1 Guest are viewing this topic.

Offline EV607797

  • Moderator
  • Location: Northern Virginia (Metro DC Area)
  • Posts: 669
Very Basic POE Switch question
« on: November 28, 2017, 12:50:51 AM »
I just got a sweet deal on a five-port unmanaged POE switch.  Super cheap, it seems to be of decent quality and even has a switch on it to allow all outgoing ports to go up to 250 meters.

Anyway, I got to thinking about this.  I'm currently using it for two VoIP phones and it works great.  What I need to know is if I connect a non-POE device to this switch, will it cause any harm to that device?  I've always understood that the blue and brown pairs in a 10/100 Ethernet cable simply aren't used in these instances.  The tip/ring of these pairs are shorted together, but they don't connect to anything within the device.  Still, I remember hearing talk of people smoking NICs in PCs by connecting them to POE switches.

I guess to play it safe, I can check for continuity between the blue and brown pairs before I do anything. 

I'd like to use a port on this switch to feed my smart TV instead of using WiFi.  I certainly don't want to cause any damage to my TV with an unexpected 48 volts.  Am I wrong here with my assumptions?
Ed Vaughn

(540) 623-7100 (V)  (540) 693-5800 (F)
EMVaughn3@Outlook.com

Online hitechcomm

  • Moderator
  • Location: New York, NJ and Conn
  • Posts: 938
    • HIZER Communicatins
Re: Very Basic POE Switch question
« Reply #1 on: November 28, 2017, 10:14:24 AM »
Ed, I would not do that. The
POE supplies power that the non POE may not like and visa versa. I think your asking for trouble.

Offline MacGyver

  • Administrator
  • Location: Dallas, Texas
  • Posts: 3796
Re: Very Basic POE Switch question
« Reply #2 on: November 28, 2017, 10:26:17 AM »
Ed, obviously I don't know every device out there, but I've never had a problem.

For example you can hook your computer and IP phone to the same PoE switch.  I was taught that power is only supplied if requested.  Otherwise it's just a regular switch port.
-I'm only here because my flux capacitor is broken.

Online hbiss

  • Administrator
  • Location: Westchester County, NY
  • Posts: 2797
Re: Very Basic POE Switch question
« Reply #3 on: November 28, 2017, 11:09:41 AM »
That's correct. If there is no POE device connected to the port there is no power on it and you can use it as a regular port.

-Hal
I gotta get out of this business...


COMSYSTEC- Phone Systems | paging systems | background music systems | foreground music systems | retail music | restaurant music

Offline ttech

  • Moderator
  • Location: Paoli, PA
  • Posts: 228
Re: Very Basic POE Switch question
« Reply #4 on: November 28, 2017, 05:44:43 PM »
There is supposed to be a handshake.  Google POE classification

Offline EV607797

  • Moderator
  • Location: Northern Virginia (Metro DC Area)
  • Posts: 669
Re: Very Basic POE Switch question
« Reply #5 on: November 28, 2017, 08:59:57 PM »
I get that, but again, this is a very inexpensive switch, designed for the support of cameras and access points.  I'm embarrassed to even say how much I paid for it.  I seriously doubt that it has any level of intelligence.  I have a feeling that there's power on the ports all the time.  It does have POE LEDs on each port though, so I guess I'll tinker with it just to be safe.
Ed Vaughn

(540) 623-7100 (V)  (540) 693-5800 (F)
EMVaughn3@Outlook.com

Online hbiss

  • Administrator
  • Location: Westchester County, NY
  • Posts: 2797
Re: Very Basic POE Switch question
« Reply #6 on: November 28, 2017, 10:49:55 PM »
If you have an old switch that you don't use just connect a patch cord from a port on it to your POE switch. The LED shouldn't come on. Then connect something that requires power. See that the LED turns on.

I can virtually guarantee you that even though that switch costs next to nothing you have nothing to worry about. What I would worry about is it crapping out sooner than later.

-Hal
I gotta get out of this business...


COMSYSTEC- Phone Systems | paging systems | background music systems | foreground music systems | retail music | restaurant music

Offline Skip555

  • Moderator
  • Location: Sarasota Fl
  • Posts: 991
Re: Very Basic POE Switch question
« Reply #7 on: November 29, 2017, 09:15:22 AM »
use a patch cord to a modular 8 conductor jack or banjo and check it with a meter . (I'm curios so now I'm going to need to try this later )

I see 24 and 48 port POE switches all the time that are powering all devices in the business .
---------------------------------------------
Skip

...Serving SW and West Central Fl since '84