House cat6a shielded cable, grounding and 10GbE

[Adrenolin]

Hello,

A buddy purchased an old building in town last fall and gave me a shout the other day asking if I'd be interested in something that was in the back room. Turns out he found a full box and a half of Cable Matters Cat6a Shielded CM In-Wall SSTP/SFTP cable, a bag full of Cat6a shielded and unshielded punchdown RJ45 keystones and a few shielded in-line couplers.

I've been planning on replacing the old Cat5 in our house for a few years and there is more then enough cable here for what I want to do. I have a small network room in the basement with a 4-post rack. Everything on it is 10GbE using Intel X54T1 network cards plugged into a Netgear 8-port XS708E 10GbE switch. All the Cat5 cables from the rest of the house come into an older Netgear 48-port GS748T 1GbE switch with 1/2 the ports starting to burn out. I really need to replace this with a newer 24-port switch with a SFP+ port.

Years ago.. a decade or more now I guess, I pulled miles of Cat5 through a number of schools and small office buildings for my employer. Simple stuff really and still have my tools.

I've watched a few videos for Cat6a shielded cable and see how its a bit more of a pita over Cat5/6. Since I'm fairly relaxed, can take my time and all this is free I'd really like to use it.



The Cable....
Aside from it being a bit more time consuming with the foil and drain wire anything that I should be aware of? Seems straight forward enough terminating into RJ45 keystones in each room and a patch panel in the basement.

* Grounding.... (Need help here!)
I understand the shielding bit and the need for the drain wire. One question here however is grounding everything since Cat6a shielded cable pretty much creates a huge antenna. Currently, everything in my rack simply grounds to the outlet it plugs into and that is that. I was looking at purchasing the Cable Matters 24-port shielded patch panel. My network room in the basement is centered in the house. Since this panel needs to be grounded whats the best way to do this?



Anything else I should be aware of? I know Cat6a shielded is more then a residential home needs however lucking into enough cable and a good number of keystones for free makes it hard to pass up.

Thanks for any comments or suggestions!

 

[Adrenolin]

Re: Grounding...

Can I attach the drain wire at the room keystone using a Cat6a shielded SSTP patch cable (metal ends) to ground via the PC and NOT attache at the patch panel?

In this case would I still use the drain wire at the patch panel and just not ground the panel or simply snip and NOT use the drain wire?

 

[Red Squirrel]

I'm not positive but I think you need to only ground one end. So you probably want to ground the rack end. For good measure I would double check that the rack is grounded, it probably is through the server cases, but it probably does not hurt to add a dedicated grounding cable. (something I need to do myself now that I think about it)

I'm kinda curious myself to know what the proper way is. Everybody someone asks on a forum they just get shot down and told not to use shielded cable, but I see no reason why not, if it's done properly.

 

[Adrenolin]

Hmm.. Ok so if I think about this for a minute...

All my equipment (servers, switches, etc) currently plug into my APCs which plug into the wall power outlet providing ground back to the panel and out to the house earth ground.

So.. If I run a ground cable from the APC to rack and fasten with a both to a smoothed section of bare metal on the rack then the entire rack itself becomes grounded.

So... If I terminate each Cat6a shielded runs foil and drain wire at the Cable Matters shielded patch panel I can then ground it directly to the rack up top... or down to the same bolt securing the ground cable from the APC to rack.

Ok we have grounding on all runs at this point.

Now.. Do I need to use shielded RJ45 keystones or can I simply use the cheaper non-shielded keystones in each room and snip back the foil and drain wire??

 

[Red Squirrel]

At the rooms I'm guessing you just use regular keystones. Keep the shield as far as you can over the wires. But I may be completely wrong here though, I'm just guessing as to what seems more logical.

 

[RadiclDreamer]

Make dang sure you ground it or you have made yourself a giant antenna

 

[RadiclDreamer]

Hmm.. Ok so if I think about this for a minute...

All my equipment (servers, switches, etc) currently plug into my APCs which plug into the wall power outlet providing ground back to the panel and out to the house earth ground.

So.. If I run a ground cable from the APC to rack and fasten with a both to a smoothed section of bare metal on the rack then the entire rack itself becomes grounded.

So... If I terminate each Cat6a shielded runs foil and drain wire at the Cable Matters shielded patch panel I can then ground it directly to the rack up top... or down to the same bolt securing the ground cable from the APC to rack.

Ok we have grounding on all runs at this point.

Now.. Do I need to use shielded RJ45 keystones or can I simply use the cheaper non-shielded keystones in each room and snip back the foil and drain wire??

Depends on whether you actually care about the shielded aspect of the cable, which it seems you do not. If you want a fully shielded connection you need to make sure you use all shielded gear, otherwise as long as you drain the wire you are golden

 

[Mr Evil]

Shielding is a complicated topic, and there is no right answer.

If you ground at one end only, the shield will still be effective against electric fields, but it will not be effective against magnetic fields. Magnetic fields are unlikely to be a problem though.

If you ground at both ends, you will have a ground loop. You can get quite large currents circulating in long cables, but it will be at mains frequency (50/60Hz), so it will not affect the Mhz frequencies of the network.

In short, it doesn't really matter, as long as its grounded somewhere (and even an ungrounded shield will attenuate noise a bit).

 

[imagoon]

If you ground at both ends, you will have a ground loop. You can get quite large currents circulating in long cables, but it will be at mains frequency (50/60Hz), so it will not affect the Mhz frequencies of the network.

You would be to busy dealing with your house burning down than dealing with corruption due to high current ground loop.

 

[Adrenolin]

I understand that it needs to be grounded. I don't wish to have a ground loop causing current passing through the cables so I'll go with the patch panel grounded to the rack which will be grounded via the APC UPS and the outlet plug back through the main house panel and then earth ground. I'll use the regular keystones in each room as well which will save some additional cash as I'll need a few more.

Anything else I need to think or worry about?

Thanks again for all comments.. it is very much appreciated!

 

[imagoon]

Personally, I wouldn't bother with shielded at CAT6a for a residence. However if you do, you need to ground (drain) the shield, typically using a grounded patch panel. That patch panel should have a dual screw lug to attach a 8 gauge grounding wire that you need to ground to your bus bar that is then grounded via at least an 8 gauge cable attached to your grounding rod system. At least based on electrical code.

If you are not going to do shielded end to end however, it is pointless and won't offer much. Leaving it unattached can cause noise issues as it will take the noise that would normally be drained and emit it in to the pairs.

 

[RadiclDreamer]

Personally, I wouldn't bother with shielded at CAT6a for a residence. However if you do, you need to ground (drain) the shield, typically using a grounded patch panel. That patch panel should have a dual screw lug to attach a 8 gauge grounding wire that you need to ground to your bus bar that is then grounded via at least an 8 gauge cable attached to your grounding rod system. At least based on electrical code.

If you are not going to do shielded end to end however, it is pointless and won't offer much. Leaving it unattached can cause noise issues as it will take the noise that would normally be drained and emit it in to the pairs.

OP didnt want shielded, but a buddy gave it to him, so hes trying to use it to keep costs down.

 

[imagoon]

OP didnt want shielded, but a buddy gave it to him, so hes trying to use it to keep costs down.

True but not installing it correctly will make it not work so he will end up stuck "paying" more to get it running well. Basically this is "Free as in puppy."

 

[RadiclDreamer]

True but not installing it correctly will make it not work so he will end up stuck "paying" more to get it running well. Basically this is "Free as in puppy."

We are all agreeing on that, and OP is taking the necessary precautions by asking how it should be installed for best result. No offense intended, but did you read the full thread? This was covered by other posters.

 

[imagoon]

We are all agreeing on that, and OP is taking the necessary precautions by asking how it should be installed for best result. No offense intended, but did you read the full thread? This was covered by other posters.

Yes, which is why I was wondering why you where stating the obvious but decided not to say anything.

 

[razel]

Don't get too excited about many of these CAT 6a cables. As bluejeanscable has shown there are VERY few that actually perform much less test at their ratings. Depending on how much labor is involved with your home setup, if you currently do not have issues, then I wouldn't bother to recable. I'd rather wait until I have an issue and then buy the right cable.

 

[razel]

Here's a recent example of supposed CAT 6 cable available at Lowes. GREAT price, but that fails basic Fluke tests at CAT6:

http://www.fatwallet.com/forums/hot-deals/1479380/?start=0

It passes fine at CAT5e and completely worth it to make your own shorter patch cables, but certified CAT 6... nope.