Technical Discussion
  >> Home Networking, Internet Connection Sharing, etc.


Register (or login) on our website and you will not see this ad.


  Print Thread
Standard User batfastad
(newbie) Tue 05-Jul-11 12:52:07
Print Post

PoE injector/splitter to get power to ADSL router, from UPS?


[link to this post]
 
Hi everyone

We recently moved office and the position where our telephone lines come into the building are in the opposite corner to where all our server gear is, including the UPS. I'm looking to have it so that our ADSL router is powered from our UPS in the opposite corner of the building, so that if the power does go off then our internet connection stays up long enough for the UPS to tell us about it.

I tried running the ADSL signal from the RJ11 connector on the filter through our Cat5E cabling to our patch panel and hooking up the ADSL router in our server cabinet but that didn't work consistently enough. We're only talking about 40m of Cat5e cable but I think the signal degradation was too much. And our ADSL speed is so bad out here on a business park that even losing a couple of Mbit is too much.

So I'm looking at the option of running power through the Cat5e cable. We already have a PoE switch which powers our VoIP telephones. Power for this switch is provided by the UPS. There's a spare PoE port and about 70W of spare PoE power capacity.
Obviously I don't have to use the PoE switch, I could use an injector/splitter instead and these passive ones look pretty interesting... http://linitx.com/product/11849
We have enough Cat5e wall sockets to be able to dedicate one for power and another for data - I'm not bothered about data and power sharing the same cable.

I have 2 different ADSL 2+ routers currently at my disposal and here are their power ratings.
A Thomson TG585v7 (BeBox) with an input of 22V 0.818A
Or a ZyXEL P-660H-D1 with an input of 12V 1A (10W max power consumption)

So I think there are 3 options:
1) use a spare port on the PoE switch and get a splitter for the ADSL router end
2) send AC mains current down a spare Cat5e cable and have the power adaptor at the same end as the router
3) have the power adaptor for the router connected to the UPS then the stepped-down (or up, can't remember my physics) current is sent over the Cat5e to go to a splitter which plugs straight into the back of the router

Option #1 needs the power requirements of the ADSL router to be PoE compliant. And as can be seen from the power ratings above, I don't believe either of them are.
Option #2 sounds fantastically dangerous.

Which leaves option #2 and one of these kits of passive injector/splitter... http://linitx.com/product/11849
Would that work?

I'd have to chop off the 3 pin plug end of a standard C13 computer "kettle lead" and add a 3 pin socket ( http://www.thetoolboxshop.com/0-722-00-pack-of-1-ful... ) so I can connect the ADSL router's power adaptor to a C14 outlet on the UPS.

Or should I just give up on the whole thing?

Cheers, B
Standard User shtu
(experienced) Tue 05-Jul-11 14:35:41
Print Post

Re: PoE injector/splitter to get power to ADSL router, from


[re: batfastad] [link to this post]
 
Option 2 is incredibly dangerous. Just. Don't.

I would probably use the passive injectors and the original PSU.

Edit -

I've done exactly what you suggest to a 4-way extension lead. If you are in any doubt about the safety of DIYing it, buy one,

http://www.comms-express.com/products/1m-uk-13a-sock...

Double Edit -

you have your C13 and C14 the wrong way round. For safety, the C13 is on the UPS body. You cannot chop the end off a "kettle lead", although a C13\C14 extension could be used as a starting point.

Edited by shtu (Tue 05-Jul-11 14:46:53)

Standard User batfastad
(newbie) Tue 05-Jul-11 15:11:22
Print Post

Re: PoE injector/splitter to get power to ADSL router, from


[re: shtu] [link to this post]
 
Great, that's what I figured.
Ah yes, apologies for getting the C13/C14 the wrong way round, that is actually what I meant. Though actually I probably will buy a pre-made one because we don't have too many C13-C14 extensions knocking around any more.

Would this work with either of the ADSL routers? Or should I go for the one with lower voltage ratings (ZyXEL)?

Sending non-PoE compliant voltages/currents down our Cat5e cabling in the trunking won't mess anything up will it?

Cheers, B


Register (or login) on our website and you will not see this ad.

Standard User shtu
(experienced) Tue 05-Jul-11 15:36:38
Print Post

Re: PoE injector/splitter to get power to ADSL router, from


[re: batfastad] [link to this post]
 
I would work out your load in watts, take a note of the voltage and curent, and compare to the poe spec. If you're less than each of these you should be OK.

Play safe and try the lowest demand first.

As to your last question, it *should* be OK, you'll just have to try.
  Print Thread

Jump to