Power Over Ethernet for ECI modem

I have an old Openreach ECI modem, can I power it via PoE? Its power supply output says 12V 1A. I'm inspired by this post so I can position my router near the master socket but away from my UPS. (The PoE injector would be on a UPS protected supply.)

Can be done?

I know nothing of PoE, I assume the injector fits between my router and the splitter and only sends power 'one-way' downstream, cos powering an ordinary Ethernet port would fry it, right?

So I just need an injector and that splitter kjwkjw uses? The specs seem to say it does 12V 1A power out.

OTOH I have read people having trouble making a FritzBox router work via PoE as it seems to demand more power than usual during startup. But maybe that's just a Fritz issue and its a full router, not just a modem.

i have never tried it, you would require a POE infector and POE Splitter

the POE splitter will convert the 48v to 12v

have a look at this https://community.fs.com/blog/what-is-poe-splitter-a...

Easy, have been running modem over POE for years. Can either use a kit (https://www.tp-link.com/uk/business-networking/accessory/tl-poe200/#overview) or POE splitter linked to a POE switch. Just need the right size DC plug to fit the modem.

I’ve used the TPLink TP-POE10R splitters to power a variety of things using network PoE over the years. One recent example below.

Just be mindful that these particular splitters from TPLink are not isolated. So it’s possible / probable that the 5V/9V/12vDC selectable output could float above ground. TPLink themselves obscurely warn about it in their docs. See ”warning” from TPLink. I’ve checked the voltage between the negative side of the barrel connector on the setup below and a grounded power socket, and it’s not showing any residual voltage, for what it’s worth.

The gear that I’ve used to power in this way has either been standalone or otherwise isolated and not connected to another power or ground source. Just be mindful with the ECI modem, although in itself it should be isolated from the line side with an isolation transformer in the modem circuitry.

Here’s test bed setup I’ve been using for the past few months that’s powering both a network connected GNSS/GPS base receiver and a fibre to coax converter (the receiving GPS antenna is quite remote - too far for coax due to signal loss - instead its connected at the other end via a matching coax to fibre converter). For ease of connection on the mock-up, the 12VDC power out from the splitter is connected to the power input of both devices via the good old wago terminals on top of the TPLink splitter. Apologies for the slightly untidy wiring, but it is a ‘prototype’ 😎

GNSS Base Receiver test mock-up

Showing reverse side of splitter (this is their latest v5 iteration, for what it’s worth)

In reply to a post by NGDragon:

Easy, have been running modem over POE for years. Can either use a kit (https://www.tp-link.com/uk/business-networking/accessory/tl-poe200/#overview) or POE splitter linked to a POE switch. Just need the right size DC plug to fit the modem.

For a PoE switch, I'm looking at getting a Ubiquity EdgeRouter X. But that's passive so not so good. Its also 24V, these proper injectors are 48V - I think. Anyway there seems to be a question as to how powerful an EdgeRouter is as far as PoE is concerned. I think a proper set may be the better, safer, option.

So why am I reading that a FritzBox router won't startup using PoE? That would be a bit of a better option than using the old modem. Naturally, I can't find the forum posting again. I think it was Italian so may have lost something in Google Translation. But the jist seems to be that the FritzBox was demanding more power on startup than expected, not getting it on PoE and going into an endless startup loop. Does that make sense? I suppose I could try and see - probably with a spare router first though!

Lastly, where do you get the correct DC adaptor and how do you know which one you need? It seems to me every mains adaptor I have is different in some way. I'm always nervous of using the wrong power source on the wrong device. And despite that, I recently killed a radio....

You can’t mix “passive” PoE with “active” 802.3 af / at / bt based kit. They are completely different beasts.

Either find an 802.3 compatible switch or injector to use. I’ve not seen any passive PoE splitters with selectable output DC voltage like the TPLink splitter above.

The Fritz is probably drawing too much power on startup (not out of ordinary) that either the splitter or switch/injector are unable to supply. See power classes of 802.3 PoE below for info:

Summary of PoE Markings

In reply to a post by Pheasant:

Showing reverse side of splitter (this is their latest v5 iteration, for what it’s worth)

Reading the output on that picture and the penny drops. The FritzBox power supply says its output is 12v 2000mA. So the TPLink wouldn't be able to power it, would it? And if so, are there other brands of PoE that could output 12v 2A? Or am I just going to have to use the ECI modem?

Yes the power budget of the TPLink is 12 watts @ 12vdc. Not massive but enough for many applications.

I don’t know of other splitters with higher power outputs off the top of my head. You’ll need to do a bit of research on that.

Also see my note above about the PoE device “classes” (particularly the switch or injector) that is actually supplying the power. It has to be of an equivalent or higher class rating of the splitter to be able to supply enough juice that the splitter is demanding. No point putting an 802.3at or 802.3bt splitter on a lower power output rated 802.3af injector or switch.

Edited by Pheasant (Thu 08-Jul-21 10:13:22)

Rather than mess about with PoE splitters and injectors why not jut use another cable in parallel. You could use Cat5e/6 (2 pair) and push the power down that.

As teh modem will only deliver 80Mbps then it only reuires 2 pairs in a normal Cat5e cable - rewire your link to just use those four and repurpose the other two pairs for power. And using two pairs would mean a lower voltage drop.

Edited by MHC (Thu 08-Jul-21 10:25:48)

If doing that then I wouldn't mess about with twisted pair cabling, but put in a proper multicore power cable. Less chance of nuking stuff too, if someone thinks it's 'just' a data cable.

Amps, volts, watts. I can never remember how they are related. But no matter...

Are there other brands which don't have the isolation problem of the TP-Link? As I understand, everything is fine and dandy when the device being powered over Ethernet is stand-alone. So a CCTV camera for example. But as soon as you are powering something which is connected to something else it becomes a possible issue. In my original post kjwkjw is powering a PON using a TP-Link. But that's passive so seems safe. My modem will be connected to the POTS and that's got power - albeit a small amount.

I don't know enough about electronics so I'd rather stay on the safe side of the road.

There are indeed. There's one from fs.com above, that has been kindly linked to. There are others.

In reply to a post by MHC:

Rather than mess about with PoE splitters and injectors why not jut use another cable in parallel.

Cos the cable is in the wall. It wouldn't be possible to run another alongside without much removal of plasterboard. Wouldn't go down well with OH!

In that case, as suggested, convert the Ethernet connection to just 2 pair, and use the other two for direct power. Yes, a bit fiddly, but you shoukld be able to get it to work using the modem PSU and approrriate connectors.

In reply to a post by Woolwich:

Amps, volts, watts. I can never remember how they are related. But no matter...

Simplifying:

Amps - the actual power.
Volts - how hard those amps are being pushed down the wire.

These are not related - one can be enormous while the other is low.

Watts - amps x volts

In reply to a post by Pheasant:

There are indeed. There's one from fs.com above, that has been kindly linked to. There are others.

Sorry, didn't realise that fs was a dealer. Their splitter is 10/100 which would be fine but not future proof. I'll look around see if a 1G exists. But the fs one has soothing words

High Voltage Isolation: 1500V (Input Stage to Output Stage)
Support protection for Short Circuit, Over- current & Over-temperature

so that makes me feel better.

Nope the EdgeRouter X is good, though I strongly recommend the EdgeRouter X-SFP which gives you some more flexibility as it has 24v passive PoE on all the five RJ45 sockets.

Then you want this

https://www.amazon.co.uk/gp/product/B00EBCQ5FM

It will power the ECI and HG612 or Vigor 130 just fine. I have one right now powering my HG612, keep meaning to swap it out for the Vigor which it also powers just fine. I have in the past used it with a ECI as well. My Edgerouter X-SFP is also powering a couple of Ubiquiti access points, a soon to be decommissioned Vodafone SureSignal (due to Vodafone turning the service off in September) and a Raspberry Pi with a different WiFi Texas splitter that outputs 5v and I chopped the plug off and soldered a microUSB on to instead

https://www.amazon.co.uk/gp/product/B00DAMKQWW

However it looks like the WiFi Texas device is unavailable so you could go with

https://www.amazon.co.uk/dp/B01MSTJJJQ

which should work too. Or contact me privately and I can sell you the one that is powering my SureSignal.

Edited by jabuzzard (Thu 08-Jul-21 13:41:00)

Looking for a 12v 2a 1G splitter I've found a couple, most with quite poor reviews. None of the 'brands' seem to do them. This one is on Amazon and one German punter says it works with his FritzBox. So that's good, I'd rather user the FB than the ECI.

No idea if its active or passive though. No idea if I will need an injector or I could use the passive 24v output from an EdgeRouter X.

Are there clues in the specs of either or should I just order one and see?

That one is IEEE 802.3af & IEEE 802.3at. Not passive 24v

Here are some other reasonably priced PoE splitters from Planet (quite a well known Taiwanese network manufacturer) that are active PoE+ (802.3at) class or PoE++ (802.3bt) class with sufficient output power to drive a router or high power device. The higher the power class, the more sophisticated is its converter circuitry and more likely it will have proper isolation built in. Passive 24V splitters tend to be a bit more proprietary by nature. The active splitters on the other hand are more interoperable as they need to be able to negotiate / handshake based on standards to work with other makes. Therefore you tend to find more active splitters that could suit your needs.

https://connectec.uk/electrical/power-supplies-psu/p...

https://connectec.uk/electrical/power-supplies-psu/p...

In reply to a post by Pheasant:

Here are some other reasonably priced PoE splitters from Planet

Thanks for that, very useful. I'd rather pay a bit more for a brand than a cheap no-name from eBay or Amazon.

OK, so do I have to get a 1 amp for a 1 amp device or can a 2 amp work? Will a 1 amp device just take 1 amp or will it get two and fry?

Obviously I did something silly when connecting the wrong PSU to a radio recently. There was a small spark and the radio was dead. But maybe I tried to use a 12 volt PSU where the radio wanted 5?

I seem to remember its the amps that kill you. But a little knowledge...

2A will be fine - the device will only take as much as it needs.

In reply to a post by Woolwich:

I seem to remember its the amps that kill you. But a little knowledge...

That is true - milliamps to be more precise. However, you still need suficient voltage there to allow te body to conduct.

Most people could safely hold teh two contact of a 12v 10A power supply, one in each hand and feel nothing. But try a 120v 10mA supply and it could well be fatal - so do not try it.

I am no electrician but are your numbers correct? I thought I would look at a livestock electric fence and found this

In reference to www.agrisellex.co.uk/pages/what-is-electric-fencing:

No, an electric fence is not dangerous. The voltage being sent through the wires is high, but the current or amplification (amps) is very low. A 220-volt shock will hurt just as much as a 10,000-volt shock, as long as the current or amps are the same. Amps are what kills. Electric fence energisers put out high voltage (around 8,000 volts), but very low amperage or current (around 120 milliamps). This is 120-thousands of an amp. It should not even kill a squirrel.

That is vastly higher voltage and amperage than your example and yet apparently "wouldn't even kill a squirrel".

For a healthly human it is believed 100mA will be lethal. However, there are people with differing "issues" and sustained 10mA could be enough in their case. RCDs operate at 30mA for most houses and are very rapid. If the body could sustain 100mA then why not make them 100mA and just as rapid? There is good reason why they are don at 30mA. You can also get 10mA one where a higher degree of protection is required.


An electric fence is pulsed and not continuous though. I certainly would not be touching an 8kV 120mA source. And I know what a 10-15kV shock feels like.

In reply to a post by MHC:

But try a 120v 10mA supply and it could well be fatal - so do not try it.

In reply to a post by MHC:

For a healthly human it is believed 100mA will be lethal.

I would be dead 10 times over if that were true.

You might be lucky ... I have been on several occasions.

A US site gives this:

Currents greater than 75 mA cause ventricular fibrillation (very rapid, ineffective heartbeat). This condition will cause death within a few minutes

https://www.elcosh.org/document/1624/888/d000543/sec...

Yes 100mA and 300mA RCD and RCBOs typically used within commercial/industrial settings for the protection of equipment and fire protection rather than safety of life. 30mA is the generally acknowledged upper safe limit for life protection, but can be too sensitive for some circuits / gear which has an inherent amount of leakage. So they set it higher to avoid nuisance tripping.

"It should not even kill a squirrel."

My electric fence killed a hedgehog It also plays havoc with ADSL if anywhere near the phone wires (and probably FTTC too, but we don't have that here).

In reply to a post by Woolwich:

OK, so do I have to get a 1 amp for a 1 amp device or can a 2 amp work? Will a 1 amp device just take 1 amp or will it get two and fry?

Obviously I did something silly when connecting the wrong PSU to a radio recently. There was a small spark and the radio was dead. But maybe I tried to use a 12 volt PSU where the radio wanted 5?

I seem to remember its the amps that kill you. But a little knowledge...

as long as volts is same, and amps is same or more it'll be fine, using 12v on something that needs 5v is likely to break stuff (best case is that a regulator runs a bit hot, worst case is magic smoke get released)

An interesting quote Ian. Unfortunately Agrisellex got there definitions wrong.

".....but the current or amplification (amps) is very low." [my bold]

amps is the usual abreviation for amperes, named after André-Marie Ampère and A is the abbreviation. Where they got amplification from, other than reverse engineering their guitar amp to amplifier, I don't know.

A good read is https://en.wikipedia.org/wiki/Electrical_injury

Cheers!

I noticed that one as well as a lot of other dubious statements in the preceding posts.

In reply to a post by Woolwich:

In reply to a post by Pheasant:

Here are some other reasonably priced PoE splitters from Planet

Thanks for that, very useful. I'd rather pay a bit more for a brand than a cheap no-name from eBay or Amazon.

No worries. Remember you need an injector (or PoE capable switch) that at least matches the same standard as the splitter to get the rated power out of the splitter. Otherwise the lowest common denominator rules.

Have fun.