PoE issues with Unifi switch



  • I have a small network in our 2nd location, with few UBNT PoE devices. Until last week all devices were powered on by old Toughswitch 5P, I guess they are called Edgeswitch 5xp now.

    I have 4 devices, Nanostation M5, Unifi AP, I think first model, with green LED, and 2 older UVC cameras. All devices are connected with UBNT Toughcable and plugs, and that thing alone is a major pain to deal with. Anyway, all devices worked fine on 5xp switch.

    Last week we added 24 port PoE switch, US‑24‑500W model. Of the 4 above devices only AP would power on, but connection wouldn't remain stable, it would turn on and off every few minutes. We also measured voltage on shield of the cable, it was leaking 50 VDC and 115 VAC. No voltage while it was connected to 5xp switch. Further troubleshooting and I ended up making non-shielded extension cable, with keystone jack on one and, and all devices would power on from Unifi switch.

    Last few days we added small rack with shielded pass-through patch panel, and connected everything through it. We had to add ethernet couplers and extra cable because original cable runs were too short, both couplers and cable are shielded. Cables from patch panel to switch were unshielded. In that setup, again only AP would power on. I had to replace cables running from couplers to patch panel with unshielded ones, to get the devices to power on.

    I have couple of PoE phones and they power on just fine. The difference is these are PoE+, and Ubnt devices are passive 24V.

    Does anyone have any idea what could be the issue here? Ubnt support didn't get me far, they asked for logs from the switch, but I'm sure problem is electrical and won't show up in logs. One difference is that ports on 5xp switch are isolated, while on patch panel and Unifi switch it's metal touching metal. Btw, sparks were flying occasionally when plugging in Ubnt devices into new switch, I guess wires from 2 cables were touching.

    Pics of setup (sorry, no cable porn, will tidy up when it's finished):

    IMG_1091.jpg
    Switch, PoE+ ports to the left, Passive 24V to the right

    IMG_1090.jpg
    Patch panel

    IMG_1089.jpg
    Couplers with unshielded cables



  • I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?



  • @wrx7m said in POoE issues with Unifi switch:

    I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?

    Nope. You connect ONE side of the shielding to ground. Managing them is a pain. Also, if shielding is required, just us fiber imo.



  • @travisdh1 said in POoE issues with Unifi switch:

    @wrx7m said in POoE issues with Unifi switch:

    I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?

    Nope. You connect ONE side of the shielding to ground. Managing them is a pain. Also, if shielding is required, just us fiber imo.

    I would imagine that the endpoints would determine that. If there is only an RJ45 port, then you are kinda stuck, right?



  • @wrx7m said in POoE issues with Unifi switch:

    I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?

    That cable is really messy. Normally you would get just aluminium foil, but these have wire on top, like coax, then plastic foil and ESD drain wire. The worst cable I had to work with. The connectors are also shielded. Everything in this setup was shielded, and ground was at patch panel. I had to break the shield between couplers and panel to get PoE to work.



  • @marcinozga said in POoE issues with Unifi switch:

    @wrx7m said in POoE issues with Unifi switch:

    I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?

    That cable is really messy. Normally you would get just aluminium foil, but these have wire on top, like coax, then plastic foil and ESD drain wire. The worst cable I had to work with. The connectors are also shielded. Everything in this setup was shielded, and ground was at patch panel. I had to break the shield between couplers and panel to get PoE to work.

    Seems like a pain, for sure.



  • @travisdh1 said in POoE issues with Unifi switch:

    @wrx7m said in POoE issues with Unifi switch:

    I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?

    Nope. You connect ONE side of the shielding to ground. Managing them is a pain. Also, if shielding is required, just us fiber imo.

    Here shielding wasn't strictly required, and fiber would be impossible, you can't do power over fiber. Also neither of the devices have fiber connection, so fiber to ethernet adapters would be required, not really practical 20 ft above the ground hanging off the cameras or antenna.



  • @wrx7m said in POoE issues with Unifi switch:

    @marcinozga said in POoE issues with Unifi switch:

    @wrx7m said in POoE issues with Unifi switch:

    I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?

    That cable is really messy. Normally you would get just aluminium foil, but these have wire on top, like coax, then plastic foil and ESD drain wire. The worst cable I had to work with. The connectors are also shielded. Everything in this setup was shielded, and ground was at patch panel. I had to break the shield between couplers and panel to get PoE to work.

    Seems like a pain, for sure.

    Literally, I was pulling wires from my fingers for a while after working with that.



  • @marcinozga said in POoE issues with Unifi switch:

    @wrx7m said in POoE issues with Unifi switch:

    @marcinozga said in POoE issues with Unifi switch:

    @wrx7m said in POoE issues with Unifi switch:

    I don't deal much with shielded. They look kinda messy. Isn't the shielding supposed to be in the connector with the rest of the cable?

    That cable is really messy. Normally you would get just aluminium foil, but these have wire on top, like coax, then plastic foil and ESD drain wire. The worst cable I had to work with. The connectors are also shielded. Everything in this setup was shielded, and ground was at patch panel. I had to break the shield between couplers and panel to get PoE to work.

    Seems like a pain, for sure.

    Literally, I was pulling wires from my fingers for a while after working with that.

    Ugh. That is terrible. Little metal splinters suck.



  • I wonder if you have a ground loop happening when you used shielded the whole way, but switching to unshielded broke the loop?



  • Shielding should be connected in both ends on networks cables. This is not an audio cable and shielding works differently for high frequency than for low frequency. A 1 gigabit connection sees 250Mhz while audio sees about 10000 times lower frequency.

    Also you'll get the best shielding when you have both foil and a braid together in the same cable.

    You will not get ground loops on networks because there are isolation transformers in every ethernet port.

    Passive PoE is not a standard. Use switches that follows the standard and you likely wont have any problems. These are the standards: https://en.wikipedia.org/wiki/Power_over_Ethernet

    BTW, rack should be grounded if it isn't.

    PS. Picture below is a network card based on Intel i350. The two black things next to each ethernet port are the isolation transformers.
    nic.jpg



  • Anyway, find the actual problem by disconnecting everything and connect things one by one.

    Real PoE for instance negotiate power the the device on the other end. I think PoE supports a crossover ethernet cable just like any switch or NIC can. But passive PoE? It'll probably short-circuit something.

    If a cable is crossed somewhere like TIA-A or B wiring in the wrong place you might have a situation like that.

    PS. You might want to get a cat6 cable tester so you can verify the wiring. A simple one would get the job done.



  • @Pete-S said in PoE issues with Unifi switch:

    Passive PoE is not a standard. Use switches that follows the standard and you likely wont have any problems. These are the standards: https://en.wikipedia.org/wiki/Power_over_Ethernet

    Not an option, Ubnt devices work only with Passive PoE.

    BTW, rack should be grounded if it isn't.

    It is. Shielding is connected on both ends, but grounded only at patch panel, and that's grounded to rack.



  • @Pete-S said in PoE issues with Unifi switch:

    Anyway, find the actual problem by disconnecting everything and connect things one by one.

    I've done that, the result is as described in op, only AP powers on, and leaks voltage somewhere.

    Real PoE for instance negotiate power the the device on the other end. I think PoE supports a crossover ethernet cable just like any switch or NIC can. But passive PoE? It'll probably short-circuit something.

    No crossover cables in use, in fact I haven't seen crossover cable since 1 Gbit became standard, even in direct connections.

    If a cable is crossed somewhere like TIA-A or B wiring in the wrong place you might have a situation like that.

    No cross anywhere, cables have been tested and mapped, during installation few years ago and again last week.

    PS. You might want to get a cat6 cable tester so you can verify the wiring. A simple one would get the job done.

    I have one, from Fluke Networks.



  • @marcinozga said in PoE issues with Unifi switch:

    Passive PoE is not a standard. Use switches that follows the standard and you likely wont have any problems. These are the standards: https://en.wikipedia.org/wiki/Power_over_Ethernet

    Not an option, Ubnt devices work only with Passive PoE.

    Sounds like you've checked all the obvious things. However the above statement confuses me.

    The new switch you have installed, US‑24‑500W, is a real PoE switch. How does it know that it should send out power to the ports where you have installed "passive PoE" devices?



  • @Pete-S said in PoE issues with Unifi switch:

    @marcinozga said in PoE issues with Unifi switch:

    Passive PoE is not a standard. Use switches that follows the standard and you likely wont have any problems. These are the standards: https://en.wikipedia.org/wiki/Power_over_Ethernet

    Not an option, Ubnt devices work only with Passive PoE.

    Sound like you checked all the obvious things. However the above statement confuses me.

    The new switch you have installed, US‑24‑500W, is a real PoE switch. How does it know that it should send out power to the ports where you have installed "passive PoE" devices?

    Each port can be set to either PoE+, Passive 24V or no PoE at all.

    switch.PNG

    12 ports to the left are set as PoE+, 12 to the right are Passive 24V.



  • PoE+ port:
    poe.PNG

    Passive 24V port:
    passive.PNG



  • @marcinozga
    Have you measured if there is any power on those ports?

    From what I could find from UBNT materials:

    24VDC Passive PoE (Pins 4, 5+; 7, 8-)



  • @Pete-S said in PoE issues with Unifi switch:

    @marcinozga
    Have you measured if there is any power on those ports?

    From what I could find from UBNT materials:

    24VDC Passive PoE (Pins 4, 5+; 7, 8-)

    I'm guessing there is, since installing a non shielded cablelet in the run solves his problem. another reason I asked about a ground loop. I don't understand the science behind the ground loop - I was way to tired to read it when posted earlier - so no clue if it could still be a culprit or not.



  • @Pete-S said in PoE issues with Unifi switch:

    @marcinozga
    Have you measured if there is any power on those ports?

    From what I could find from UBNT materials:

    24VDC Passive PoE (Pins 4, 5+; 7, 8-)

    I didn't, but I don't have to, all devices are powering on just fine with unshielded cables. The most bizarre thing is that cables from switch to patch panel are unshielded already, it's cable between panel and couplers. And I don't think I mentioned it before, but initially there was a shelf on the wall and all cables were plugged in directly into switch, with same end result. I'm strongly leaning to the fact that shield on all cables are connected with unifi switch or patch panel, and that's the root cause of the problem. Otherwise why would everything have worked on 5xp switch (isolated ports) or when cables going to patch panel are unshielded.


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