How many Ethernet pairs Can I use for Power over Ethernet

[Manfred Takondwa Makawa]

We had a setup using a phone connection box where we passed power for the Mesh Potato over the Ethernet cables but we only used one pair (2 wires). Should we change to use 2 pairs (4wires) instead of two? Does it in anyway affect performance or does it cause some sort of voltage / power drop?
The pictures attached are how it is connected over the Ethernet and terminated on the other end.

[T Gillett]

What is the length of cable?

On 31/03/2016 9:02 PM, "Manfred Takondwa Makawa" <mtma...@gmail.com> wrote:

We had a setup using a phone connection box where we passed power for the Mesh Potato over the Ethernet cables but we only used one pair (2 wires). Should we change to use 2 pairs (4wires) instead of two? Does it in anyway affect performance or does it cause some sort of voltage / power drop?
The pictures attached are how it is connected over the Ethernet and terminated on the other end.

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[Manfred Takondwa Makawa]

It is 8 - 10 metres

[T Gillett]

Hi Manfred

Generally, if you have a spare pair in the cable, you may as well use it for the power feed.

The loop resistance for a single pair in Cat5 cable is around 2 Ohms.
So for two pairs it will be around 1 Ohm.

An MP02-FXS will draw peak current up to ~250mA, so a 10 metre length of cable will drop 0.25 x 2 = 0.5 Volts, or 0.25 Volts for 2 pairs.

The MP02-FXS will operate correctly with a supply voltage greater than 10 Volts, and up to 15 Volts.

There is more information on the page below on the VT Wiki:

   http://wiki.villagetelco.org/Power_over_Ethernet_for_MP02_and_TP-Link_Routers

Regards

Terry

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[Steve Song]

Hi Manfred,

It is quite possible that there is a sufficient voltage drop over that distance, using only one pair of wires, that might impair the performance of the MP2.  With the first generation MPs, we found this would first affect the performance of the FXS port.  I would recommend using two pairs.  Does the MP2 function normally over a standard power connection?

Regards... Steve

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Steve Song

+1 902 529 0046

http://villagetelco.org