Can you use a POE switch with another POE switch?

I'm sure this is gonna make some that do this for a living cringe, but can you put a POE switch on a POE switch (or really any switch)? Here is my thinking. This Thread got me thinking about replacing our Vivient cameras. they are POE on Wi-Fi adapters plugged in in the attic. I was wondering if I were to switch them out with Foscam, if I could put a POE Switch in the attic Connected to the main switch inside the house. At least initially that seems to be the path of least resistance. Just reuse teh POW cables that are alredy up there, and instead of them connecting to POE Wifi adapters, connect them to a POE switch (which would also allow me to add more cameras later) and drop a line from that switch into the main switch in the house. I look forward to any thougths or better ideas.

If I understand your question - can a switch be plugged into another switch, then yes. If you expect to power that switch via POE, then no. The power draw would be too great. And I doubt you could find a POE switch that can be powered via POE.


This is actually possible. While it is quite rare and has power limitations (as incoming power has to be split accross child connections).

Here is an example
Gigabit Plus Switch Series - GS105PE | Plus Switches | Switches | Business | NETGEAR
Sometimes it is referred as a PoE pass-trough switch. Classic 48V standard(s)

There is another option with other restrictions:
Typical ethernet cable has 4 pairs of wires. If you are ok loosing connection speed down to 100Mbps, you can split ethernet cable (not literally, there are premade connectiors or one can be DIY) into 2 signal pairs and 2 power pairs (100Mbps needs only 2 pairs on 1,2,3 and 6th contacts).
Any voltage in range of cable restrictions can be connected.

And finally there are sort of "dummy" injectors/splitters. The main difference from the classic PoE - they can't detect voltage levels. They will pass what they are designed to. If there is some switch in between endpoints, it has to be bridged around (like splitter-switch-injector). These are not compatible with classic PoE. Often used on 12V for distant camera powering. The basic principe is the same as in the classic PoE case.

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No, it would be plugged in to its own power adapter. I just didn't know if you could have two switches in a sequence like that.,

You can daisy chain many switches this way. This is how large networks are created.

You can do that pretty much with any switch. Modern poe switches can detect the type of connections they get. Older versions weren't as smart and could toast a none poe device (including another switch). So connecting another switch is just fine for your expansion.

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You could put more than two switches in series like that, if you needed to.

ATM I have a large UniFi switch in the basement, which connects to an in-wall access point-plus-switch in my office upstairs (powered by PoE), and another small switch in the office connected off of the in-wall access point.

As long as they are new/modern devices (not an old device like an Ethernet hub), like @rlithgow1 said, as a practical matter you can pretty much add as many switches as you want.

Your router/dhcp server will keep handing out new addresses to devices as they connect to the network through your add-on switches.


Man... Ethernet HUBS... I have not seen any of those in a long time. Glad those days are long past us, just like token ring and other fun stuff. Although all of that was still better than making modem pools.


I keep a 5 port handy because it can be handy for sniffing..


That just put the entirely wrong image in mind until I realized you meant PACKET SNIFFING. :smile:

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Smell Hand Sniffing GIF by Mitski


So next question. Since I’m taking about putting this switch in the attic (and it’s not a finished attic) is heat a big dea with the switches? Or not really. Over this summer by temp sensor up there was dead (died last winter and I never noticed) but I would estimate temp up there easily hit 120f (he’ll even the outdoor temps were getting that high). The equipment closet in the house was hitting about 93. Is that something I need to be to concerned with? I’ve debated moving the modem into the garage (averaged 99 to 103 over the summer). So how much of an issue are temps?

Look at the temp rating of the device you choose. Make sure your attic exhaust fan works. Some are ok, some aren't in terms of temp

Although this isn’t what the OP wanted but this is a POE powered switch with reduced output POE ports.

I use this outside to power some POE cameras.


True, that wasn’t exactly what I was thinking, but it does seem to fit my need. Interestingly, I’m considering upgrading my network stuff and was considering moving to ubiquity when I get to that part of the project. Does this thing need to work downline from a ubiquity switch? Or can it be used with any other POE switch? And in this instance, POE cameras are what I was looking at.

OK OK. I stand corrected. :pensive:


It doesn’t need to be adopted into a Ubiquiti network but it shines there because it becomes managed centrally. Ubiquiti is a rabbit hole both feature and cost wise and a love / hate relationship.
Will work standalone, just check your cameras conform with the spec of the downstream ports, inparticlar power. In my case they are Ubiquiti Flex cams and they do work OK although I only have 2 cameras connected this way though. not sure if I can connect more.

I have a full Ubiquiti UniFi network stack and it works really well. I have even added a bunch of UniFi Protect cameras to the system, which are all local.

You may want to take a step back, and consider the entire project and perhaps accelerate a full network overhaul. If you are already considering Ubiquiti, perhaps, now is a good time?

I really enjoyed building out my UniFi network. It is not exactly cheap, but it is very user friendly. Not quite as trivial as a typical home router, but way simpler than managing an enterprise Cisco network solution. :wink:


I've never liked the ubiquiti back end stuff but I love their ap's.

I would avoid putting electronics in area with that kind of temp. it will shorten the life of your switch for sure.