Is it possible to use Active PoE splitter that does comply to 802.3af, with passive PoE injector?

  • 802.3af does autonegotiate
  • Does negotiation take passive PoE into account?

Acording to: This answer @ networkengineering

Polarity is required on data pairs, and ambiguously implemented for spare pairs, with the use of a diode bridge.

That would mean, unless the negotiation does not allow fallback to spare pairs, or let's the DC pass through (dangerous?), or just does not operate at all (would be useless), it should work.

Note: The device also has to power itself before it can do anything, which means it has to by default tap into both possible powersources internally. Even if that is a low current path.

According to: Fundamentals of Power Over Ethernet, page 5, flowchart.

  • Negotiation is managed/initated by injector
  • The splitter does provide a signature

Which does imply, given the standard (previous quote), it should automatically inteligently use the power on the spare lines.

  • 1
    that depends on your splitter. Does it care if it's attached to a passive source?
    – Ricky
    Feb 19, 2016 at 23:35
  • That is something I am not aware of. It is atypical splitter I am considering purchase of. ...
    – gw0
    Feb 19, 2016 at 23:43
  • (Will answer this question myself if I decide to buy the adapter)
    – gw0
    Feb 20, 2016 at 18:01
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 13, 2017 at 17:42

1 Answer 1


Generally, no.

There are some splitters that are compatible with pre-standard, proprietary and passive power delivery variants but unless you make a lucky match it won't work. Furthermore, running a passive injector with an incompatible PD on the other end might well cause some damage.

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