Question on Punching Down Cat6

[Swancoat]

I want to punch down a bunch of Cat6 cables into a patch panel (with the 'linear' style punch downs as opposed to the kinds with punchdowns on either side like a keystone).

I've looked up a few tutorials, bought some spare wire and a practice panel to practice with.

My question is: I know the pairs should remain twisted as long as possible, but do the pairs all have to be the same length?

With the way the punchdowns are aligned, and the cabling running parallel with the punchdowns, I want to have the blue pair being shortest, slightly longer to green, longer to orange, and then brown the longest span outside of the shielding. This seems to help keep things very neat and organized, but my fear is that it may not be to spec or somehow impede performance.

A lot of tutorials show them running the cable up the the middle of the punchdown, and aligning the pairs in a more 'fanned out pattern'. Then then need to bend the cable in what doesn't look to be a natural way in order to run them. Just wondering if that method is necessary.

Any experts willing to chime in?

(Hopefully this is clear. If not, I'll try to get some pics).

Thanks!

 

[Sacedog]

IMO the pairs do not need to stay the same length for almost all applications. It is very common for the wire to be at a 90 degree angle to the punchdowns, coming out the side; in which case all pairs woudl be slightly different length.

The only time that pair length might matter, is when you are using Cat6 (or Cat5/5e) to distribute video signals. In these instances, you would like to have the pair lengths as close as possible.

 

[Frunple]

Cat6 patch panels actually have the punch downs (110's) with 2 pairs on top and 2 on the bottom, instead of all four pairs next to each other. IOW, where you see patch number 1 on the top of patch number two, it would actually be patch 1 pair 1,2 then patch 2 pair 1,2 in the same space as patch 1.
This way you actually put the sheathing in the center of all 4 pairs and two pair go up, two pair go down with less than a 1/2" of pair out of the sheathing. Theres usually a "clip that you put the cable into that holds the pairs in the right places, then the clip is clipped into the patch and the pairs are punched down.

But to answer your question, no they don't need to be the same length. Just keep them neat and not twisted around another cable etc.

 

[Swancoat]

So this is what I was hoping I could do...

 

[Swancoat]

...and hoping I wouldn't have to do this:

Is this correct?

Frunple, are you saying the Cat6 panels will have different punchdowns? (I tried googling for an image, but every time I find an elusive Cat6 patch panel, I can only find images of the front). The pics show a Cat5 panel I bought for practice just because it was cheap.

 

[Frunple]

I'm saying you can do what you "hoped you can do" and it will be fine. Think about it, the only thing the sheathing does is hold the pairs together so as long as you keep the twists as far as you can (right up to the 110) you'll be fine. I actually bark open the sheathing at the same place for all of my cables and run the "open" pairs from that point to their punches. As long as you keep the twists its fine. Hell we have cat6 cable that doesn't even have sheathing on it just for doing cross connects.

I was just pointing out that there is an actual cat6 grade punchdown that enables you to keep the twists as far as possible because it has two pair on top of the other. So in you "not hoping" picture, you see the brown and green puch down (you have the brown and orange pair on it for some reason), well the brown and green punches below it would be the orange and blue of the same patch. So you maintain the actual pair twists and also maintain the twists of all the pairs as far as possible.
Bicsi is the "standards" organization that makes all this stuff up, you can find a lot of info on their site. bicsi.org

 

[Swancoat]

I'm saying you can do what you "hoped you can do" and it will be fine. Think about it, the only thing the sheathing does is hold the pairs together so as long as you keep the twists as far as you can (right up to the 110) you'll be fine. I actually bark open the sheathing at the same place for all of my cables and run the "open" pairs from that point to their punches. As long as you keep the twists its fine. Hell we have cat6 cable that doesn't even have sheathing on it just for doing cross connects.

I was just pointing out that there is an actual cat6 grade punchdown that enables you to keep the twists as far as possible because it has two pair on top of the other. So in you "not hoping" picture, you see the brown and green puch down (you have the brown and orange pair on it for some reason), well the brown and green punches below it would be the orange and blue of the same patch. So you maintain the actual pair twists and also maintain the twists of all the pairs as far as possible.
Bicsi is the "standards" organization that makes all this stuff up, you can find a lot of info on their site. bicsi.org

Thanks Frunple - that's just what I wanted to hear!

(FYI, I think I mixed up green and orange since I was just practicing and wired to the 'A' spec instead of 'B'.).

 

[Swancoat]

One other thought...

On the topic of equal length requirements for video signals, how stringent is that requirement? I understand you don't want to use a 10' run and a 100' run just because you had a long cable kicking around. But what if you have a run that's 50' and another one that was maybe 50.5' is that good enough? (say if 2 wires were run to the same location, but in the termination process, the lengths were altered slightly).

What about at the punching down level? Are the different lengths of the punchdown mentioned I showed above enough to mess things up?

 

[Sacedog]

One other thought...

On the topic of equal length requirements for video signals, how stringent is that requirement? I understand you don't want to use a 10' run and a 100' run just because you had a long cable kicking around. But what if you have a run that's 50' and another one that was maybe 50.5' is that good enough? (say if 2 wires were run to the same location, but in the termination process, the lengths were altered slightly).

What about at the punching down level? Are the different lengths of the punchdown mentioned I showed above enough to mess things up?

You probably not going to mess anything up with different lengths at the punchdown, for almost all video distribution systems. Most are digital now, which somewhat alleviates this issue. Any time you run services over multiple cables, you can experience issues. For example, if you are using VoIP over bonded T1s, and one of the T1s has an extra 20' of cabling coming from the MPOE to the wiring closet, you will likely have issues with the voice quality. So, for analog video distribution, you are sending three different signals, Red, Green, and Blue, and all three should get to the destination at the same time, or you might not have optimum video quality. Will it be that noticable..probably not unless there are substantial differences in pair lengths.

It is just a good idea in cabling, though, to be as neat and precise as possible. The pictures above would be suitable for any situation, IMO.

Also, for video distribution, you could just use Sage TV with extenders running on your Ethernet network, and never have to worry about it. :huh:

 

[Swancoat]

One other thought...

On the topic of equal length requirements for video signals, how stringent is that requirement? I understand you don't want to use a 10' run and a 100' run just because you had a long cable kicking around. But what if you have a run that's 50' and another one that was maybe 50.5' is that good enough? (say if 2 wires were run to the same location, but in the termination process, the lengths were altered slightly).

What about at the punching down level? Are the different lengths of the punchdown mentioned I showed above enough to mess things up?

You probably not going to mess anything up with different lengths at the punchdown, for almost all video distribution systems. Most are digital now, which somewhat alleviates this issue. Any time you run services over multiple cables, you can experience issues. For example, if you are using VoIP over bonded T1s, and one of the T1s has an extra 20' of cabling coming from the MPOE to the wiring closet, you will likely have issues with the voice quality. So, for analog video distribution, you are sending three different signals, Red, Green, and Blue, and all three should get to the destination at the same time, or you might not have optimum video quality. Will it be that noticable..probably not unless there are substantial differences in pair lengths.

It is just a good idea in cabling, though, to be as neat and precise as possible. The pictures above would be suitable for any situation, IMO.

Also, for video distribution, you could just use Sage TV with extenders running on your Ethernet network, and never have to worry about it. :huh:

I was actually thinking in the context of using HDMI baluns which require 2 equal lengths of Cat6. My gut tells me that 6-12" shouldn't make any difference, but I'm not the scientist designing these things.

 

[litemyster]

The RGB Video signals go on one Cat6 cable and Data (HDCP, CEC, EDID, etc.) goes on the other Cat6 Cable. Length of the two cables compared to each other isn't the issue, rather length of the pairs in each cable is the issue, specifically on the Video side. Some video baluns are designed to work with regular cat5/ cat6 cable and incorporate skew correction, others require special skew free cable, which won't work well for network. Generally avoid cross connecting Video over cat cable, the baluns generally don't tolerate it very well.