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April 8, 2016
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Is it possible to run 2 IP cameras off one cat5 cable by using POE protocol 802.3af endpoint alternative A (Phantom Power)
pigtail w/or pair and w/gr pair on RJ45 plug
pigtail w/bl pair and w/br pair on RJ45 plug
assumption is that both cameras are within 1 to 2 foot of each other corner of house soffit.
with proper weather proofing on connections.
Has anyone had any successs with this?
January 3, 2014
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One must calculate the power draw of the camera. Without this I cannot answer your question as it may be too much draw from one single point, being that on 802.3af each connection can only handle up to 12.95W after traveling through the cat cable.
Lets say if the camera draws 1mp at 12VDC you are looking at 12 watts of power, adding another one to the mix would be double that and this is calculating it without the IR's operating.
Jose Malave - IT Director| Toll Free: 866-573-8878 | E-mail: support@securitycameraking.com
April 8, 2016
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Allow me to try and explain my theoretical connection as I do not have the equipment to try this idea.
equipment:
1- dahua 8 Channel 4K NVR with 8 POE Product# NVR-ELE8M-P4K
2 - dahua 3MP IP Network Security Camera Product# IPOD-EL3IRE 802.3af
125 ft run of CAT5E STP wire
run the wire between the the NVR and the the location of the 2 cameras.
break the the w/or and w/gr pairs out and terminate in RJ45 plug on pins 1-2-3-6
break out the w/bl and w/br pairs out and terminate in RJ45 plug on pins 1-2-3-6
Now I will demonstrate my total lack of knowledge of POE.
after plugging in both RJ45's into the NVR and the two cameras , would the NVR sense that there is no resistance on the pins 4-5-7-8 of both camera's and see resistance on pins 1-2-3-6 and apply protocol 802.3af endpoint alternative A (Phantom Power) to power both cameras ?
as a follow up question if the above does indeed work. If I were to run another single wire and terminate RJ45 plug with all pins and plug in to a camera and NVR would it sense resistance on pins 4-5-7-8 on that camera and use 802.3af midspan alternative B protocol.
The question being, does this NVR support both 802.3af protocols at the same time?
At this time I would like to express my gratitude to security camera king for this support forum. You would never get this from a purchase direct from an asian company. Than you !
That is not something I would recommend trying. If you mess up you are going to damage something permanently.
April 8, 2016
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Thanks for the advice ! I will file it with "Don't smoke in bed".
Perhaps you did not see the word "theoretical" used in the post. I am just exploring a possible HACK to run 2 cameras on one cable run.
If you know for a fact that the Dahua only supports one protocol or the other and that trying the wrong protocol will cause damage then that would be extremely useful.
How do you think that POE came into existence. Somebody pose the question "hey we got 4 conductors in that wire that isn't being used ".
I know I have used the extra pairs to run another computer ethernet connection without any problems. I am sure that I could do the same with 2 cameras using external power to both.
Just trying to get a conversation started to see if this hack would be possible.... 
theoretically
January 3, 2014
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red-wolf
In theory it make sense up to the point were the power draw needs to be taken into consideration as well as ensuring the TX and RX does not suffer too much loss.
I do enjoy these types of topics.
Keep e'm coming 😉
Jose Malave - IT Director| Toll Free: 866-573-8878 | E-mail: support@securitycameraking.com
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May 15, 2015
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I think it will take some time to get the answer we are looking for, we'll need to get in touch with the engineers. In my mind - this working depends on whether the NVR uses Passive POE or Phantom POE. If it's passive POE - that uses your unused pairs. If they use Phantom POE then your plan might work. We just need to know how the POE works on the NVR.
I may be totally off the mark here, but that's my 2 cents worth.
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