PoE+ Patch cable question

Superficial · 1 Mar 2023 at 01:48

Hi,

I'll be installing some quite long runs (30m to max 90m) of Cat6a cabling for up to 9 PoE+ devices. The infrastructure cabling will be Cat 6a AWG 23 Pure copper solid core U/FTP which should be fine for data and power.

The cables will terminated at a patch panel as usual and patched to two PoE+ switches.

Do I need to worry what type/quality of Patch cable I use? Or would basic 0.3/0.5m stranded patch leads be fine to carry the PoE power to the patch panel without sacrificing any power loss? Does patch quality of such short distances matter?

I wouldn't normally worry but I'm close to 100m max distance for PoE as it is you see.

Thanks,

WJA96 · 1 Mar 2023 at 07:04

Use any appropriately rated speed cable of whatever length you need. They’re fine even up to 90W power draw.

WJA96 · 1 Mar 2023 at 07:06

And 100m isn’t the maximum distance, it’s the maximum distance where you can reliably certify a cable at the claimed speed rating. So it might not run at 10GbE but it could be fine at 2.5GbE etc.

Superficial · 1 Mar 2023 at 13:23

WJA96 said:
And 100m isn’t the maximum distance, it’s the maximum distance where you can reliably certify a cable at the claimed speed rating. So it might not run at 10GbE but it could be fine at 2.5GbE etc.

100m is the longest you should be running a cable for PoE as per any guide I have seen. Happy to be proved wrong.

WJA96 · 1 Mar 2023 at 13:35

Get yourself a 305m drum of cable and terminate both ends. Then try powering up an access point or surveillance camera and I bet it works just fine but possibly not at 1GbE - it might drop down to 100Mbps or even 10Mbps but it will very likely work.

Armageus · 1 Mar 2023 at 13:50

Superficial said:
Do I need to worry what type/quality of Patch cable I use? Or would basic 0.3/0.5m stranded patch leads be fine to carry the PoE power to the patch panel without sacrificing any power loss? Does patch quality of such short distances matter?

If you've got to the effort of Cat6A for the main cable runs and patch panels, then I'm not sure why you wouldn't buy Cat6A rated patch cables?

Superficial said:
I wouldn't normally worry but I'm close to 100m max distance for PoE as it is you see.

As @WJA96 has already said - that's a specification not a limit. PoE doesn't care if your cable is 101m - as long as the data signals can still be differentiated clearly, and the voltage doesn't drop too much you can often travel further than specifications.

(Equally it's entirely possible to not be able meet specifications for cable length, if there are large amounts of interference present, termination done to a poor standard, cables not constructed adequately e.g. wrong AWG - despite being labelled to a certain standard etc)

Superficial · 1 Mar 2023 at 14:24

Armageus said:
If you've got to the effort of Cat6A for the main cable runs and patch panels, then I'm not sure why you wouldn't buy Cat6A rated patch cables?

Whether it's Cat6A or Cat5 would make no difference over 30cm. My question is about whether I should worry about using lesser quality stranded patch (which is readily available) or whether I should indeed opt to make buy some solid core awg 23 connections from the patch panel to the switch. I'm asking this as this is the longest run I've made for PoE and I may or may not have enough cable left after the install.

I'm equally aware I may be over thinking and any advice i have received regarding never using stranded patch or even CCA over such a short distance is irrelevent.

Armageus said:
As @WJA96 has already said - that's a specification not a limit. PoE doesn't care if your cable is 101m - as long as the data signals can still be differentiated clearly, and the voltage doesn't drop too much you can often travel further than specifications.

That is the issue I am querying - the install has not started and I'm planning it and I do not want to take the risk of losing unnecessary power straight from the switch before it even gets to the patch panel. If it's a non issue then great if not then I need to know before I start.

Regarding your comment on voltage drop that is the concern here and I don't want to potentially exacerbate. Opinions are very divided on the issue and a lot of advice even says keep cable run to 30m or less for reliable PoE though I think that is for PoE not PoE+

Armageus said:
(Equally it's entirely possible to not be able meet specifications for cable length, if there are large amounts of interference present, termination done to a poor standard, cables not constructed adequately e.g. wrong AWG - despite being labelled to a certain standard etc)

Well quite so I better plan well within spec then.

---

In any case I've decide to purchase some high quality pure copper pre made patch cables and am prepared to install PoE repeaters on the longest cables if required but i doubt they will be.

Armageus · 1 Mar 2023 at 15:51

Superficial said:
Whether it's Cat6A or Cat5 would make no difference over 30cm.

It absolutely does - your chain is only as good as your weakest link. If your patch cables are Cat5, then your link is Cat5.
30cm may not be significant, but at higher speeds i.e. 10Gb, it can make the difference between it working or not (particularly in an interference rich environment etc)

Superficial said:
My question is about whether I should worry about using lesser quality stranded patch (which is readily available) or whether I should indeed opt to make buy some solid core awg 23 connections from the patch panel to the switch.

Patch cables should always be made from stranded - the whole point is to allow them to be more flexible. For fixed cabling runs, the spec allows for 90m of solid horizontal cabling, with 5m of stranded patch cable at each end.

Superficial said:
If it's a non issue then great if not then I need to know before I start.

Regarding your comment on voltage drop that is the concern here and I don't want to potentially exacerbate. Opinions are very divided on the issue and a lot of advice even says keep cable run to 30m or less for reliable PoE though I think that is for PoE not PoE+

It's a non-issue - the spec for all PoE is 100m.

Superficial · 1 Mar 2023 at 16:27

Armageus said:
It absolutely does - your chain is only as good as your weakest link. If your patch cables are Cat5, then your link is Cat5.
30cm may not be significant, but at higher speeds i.e. 10Gb, it can make the difference between it working or not (particularly in an interference rich environment etc)

It's not relevent to this scenario as described - it's a standard comms cabinet. Speeds would have to be tremendous for this to be an issue at this cable length and in this environment for Cable grade to matter. My concerns regard PoE not data speed as i am less experienced with longer run PoE hence the thread.

Armageus said:
Patch cables should always be made from stranded - the whole point is to allow them to be more flexible. For fixed cabling runs, the spec allows for 90m of solid horizontal cabling, with 5m of stranded patch cable at each end.

I know what standed patch is for but Good to know that the spec dictates for 10m of patch - I couldnt find that anywhere. Thanks

I'm not going to but making a few patch cables from remaining solid core cable won't hurt in this environment. Solid core is more fragile yes but these patch cables wouldnt be moved much.

Armageus said:
It's a non-issue - the spec for all PoE is 100m.

No the spec dictates that as maximum length not accounting for cable grade and EM interference and before corrosion over time is factored in. All of these factors may affect my install hence me (over) worrying about introducing poor stranded patch which is absolutely not typically rcommended for PoE ussage and CCA is an absolute no no typically.

Thanks for your help.