[asterisk-users] POE Splitters

[Karl Fife]

----- Original Message ----- 
From: "David Gibbons" <dave at videon-central.com>
To: "Asterisk Users Mailing List - Non-Commercial Discussion" 
<asterisk-users at lists.digium.com>
Sent: Thursday, July 22, 2010 1:58 PM
Subject: Re: [asterisk-users] POE Splitters


> There is no such device -- it's outside of the POE spec.
>
> Class 3 devices are allowed to consume at max 15.4W. Most phones are class 
> 3
> devices. The math just doesn't work out. Even if you used the draft 
> standard
> for class 4 (~30W), you could still power max 2 devices at 15W/ea.
>
> -Dave
>
> On Thu, Jul 22, 2010 at 2:46 PM, Matt <mhoppes at gmail.com> wrote:
>
>> I've got an interesting situation where I have one cable run from the 
>> feed
>> area to the service area.   I have three devices that I need to power at 
>> the
>> service area.  Is anyone aware of a device that will take the POE from 
>> the
>> cable run and then allow me to split it to two or three devices at the
>> service end?
>>
>> When I search for splitter all I get are the injectors, but I figure
>> someone has to make something.... I realize I'll need a power adapter 
>> with
>> enough amps to power the full load at the end.
>>

You could do someting with passive POE--in other words not 802.2af POE, but 
rather the 'dumb' kind of POE which just injects power on the unused pairs. 
Passive POE (being passive) does not have a hard wattage limit per drop 
limitation imposed by 802.2af.  On the far end, you could split out the 
power to run a 4-port 802.11af POE switch.

Passive POE would preclude GigE, but at least you wouldn't have to add 
ethernet drops.  In theory you could preserve GigE by looking for a IEEE 
802.3at [sic] switch.  IEEE 802.3at allows 36 watts per port, but good luck 
finding (or affording) a 802.3at-powered 3-port 802.2af POE switch even if 
all 3 downstream devices don't draw the maximum wattage simultaneously :-)

-Karl