atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring "Split" CAT5 wire - 2 pair data / 1 pair telco?

Hi folks,
I know that you CAN take an existing CAT5 wire and "split" it so you don't need to run a separate pair of wires for voice...but is it smart to do so?

I've read on some sites people say that if you DO that, you'll likely get reduced data speed, perhaps poor voice quality, etc. In a nutshell, it's a jerry–rigged way to go, and if you're really concerned about performance, etc...don't do it - run a separate pair of wires for your telephone from the start.

Comments? "1st hand" experience?

Thanks!

Ed

I've done it more times than I can count with no negative effect. My house was wired with four pair DIW cable that was split. I never had any issues, even with VOIP phones on it.

You can't split C5 and remain C5 because it requires all 8 conductors. If you split the cable, you can only push C3.

Although it isn't recommended, it works fine. It's amazing what Ethernet will really tolerate. I have a 205' piece of 6-pr PE89 cat nothing to the garage and run 100meg Ethernet, one Partner phone and two analog stations with no issues.
Mike

Thanks gentlemen!

Dave S. - are you saying if I DO "split" the cable (which, in laymen terms, simply means taking a 4 pair, CAT5 cable and using 2 pair for data connectivity, and 1 pair for phone connectivity, right?), the data speed will be dramatically reduced???

Do I understand you correctly???

Ed

in my opinion its a bad practice , I had one here for while at the house but I wouldn't do it for a customer and I certainly wouldn't do it simply to save money it should be considered only when there is no other practical option

What everyone else said. Yes it works, I would not recommend it, but I have done it.

The original 568 spec allowed for this, except they wanted you to use an adaptor to pull out the blue/white and brown/white pairs. The idea was that the integrity of the cable remained intact all the way to the jack. What you plugged into the jack was your business.

10BaseT ran on pins 1,2,3,&6 (wh/or, wh/gn) - but that's a maximum of 10mbs. I don't believe you can push 100 mbs through on 2 pair, but you might.....

You also might be able to if you used the white/brown for voice- but all this depends on using older equipment.


The main point, as everyone has been saying, is that it's not recommended. It will certainly work. And if you were stuck - well, then the answer is maybe. At least for a short term solution.

For yourself - do what you want. A lot of residential will never run Internet much faster then 10 mbs anyway.

Sam

Here is my take:
10BASE-T is Cat3 and uses only two pair.
100BASE-T is Cat5 and requires all four pair.
100BASE-TX is Cat5 and uses only two pair but I'm not familiar with it.

I believe the reason many have success splitting the data cable is because many users are actually served very well by 10BASE-T. Actually, think of a 10/100 switch with many users. The backbone may be 100Mbps but if they all demand bandwidth at the same time, they are only going to get something close to 10Mbps and probably not even notice the difference.

Now think about your bandwidth to the internet. most of us don't have anything near 10Mbs! I have 6mbs max with cable and my son and I can both stream Netflix at the same time and we seldom have a problem. Now, if I could just get my neighbors onto a different node!

Dave - i think you are wrong on the 4 pair thing .... my understanding is that fast ethernet / 100 Base T uses 2 pair... one for transmit and one for receive. When you step up to gigabit you use two pairs for transmit and two for receive.

But ... i could be wrong... i am a phone guy not a CG! :rofl:

upstateny is right on the button.i have a client its a hotel when they built it they only ran cat5e
for network and forgot for phones so i use w/br pair for analog set never had any issues

when I was using it here it worked fine for surfing the , net printing was slow so I substituted a switchlet .

now I was just using it for two data drops no phone

there are two types of Gigabit, 1000Base-T and TX. the T uses all 4 pairs and the TX uses just two, but requires CAT6 cable. I am not sure how they are doing POE on 1000BaseT unless they are just mulitplexing the data over the power.

Many here are claiming that 100mb cannot be achieved on just 2 pairs, while in fact that’s all that is required. To prove the point, companies have gotten so cheap that many of the factory made patch cords that come with the low end routers consist of only 2 pair now. Pins1,2 and 3,6 that all folks. Now whether this is good practice is another issue, but as far as throughput is concerned 100mb all the way. Gigabit is another story.

100Mb on 2 pairs is 10/100 specs. Above is 1 Gigb. That requires a FULL 4 pair or fiber.

You can't get another cable run?

I recently had a "frugal " customer building a new building , all drops in conduit in the slab and they where looking to run 1/2" conduit because the architect said that one cat5e cable could be used both voice and data

I wanted 1" for future but got 3/4 for separate cables

false economy in my opinion

Absolutely... i would never do this in a new install .... but in an existing building that is tough to run cable i don't have a problem explaining to the customer that this isn't the correct way to do it but it may very well work just fine for them and if they are ok with it we'll give it a shot.

I can't imagine an architect making that call ..... usually they put twice as many drops as needed!

Most architects I know are voice and data experts… not.

At UT we had a bunch of existing data wiring that was done in the early 90s...they ran one cat 5 cable for 2 jacks, one jack with the blue/orange pairs, one jack with the green/brown pairs, punched down to Krone blocks, which were then cross-connected to a 66 block with 25 pair cable, which fed to a 10BaseT patch panel in the data rack.
Needless to say these runs are all abandoned in place now.

So much hair-splitting over copper wire. Give me a coat hanger and I'll give you an Ethernet connection.

Dave Taylor has the specs straight and Ed has reality straight.

how many cat5e coat hangers in 100 meters and how do you crimp the rj45 plugs on the ends ? :rolleyes:

I've come across this at a new customers site,and when we upgraded their switches to gigabit (full duplex)we had to upgrade the cabling.it was a "sparkie" install.it was good for us, not so good for the customer.we always stay with the specs for this reason!

I think we have allowed cable manufacturers to convince us that computer data and phone data can't survive together inside the same cable jacket. We have forgotten that 10baseT was designed to work with exisiting telephone wire using spare pairs. On page 79 of my MSCE Networking Essentials Study Guide is a diagram of how to connect data to an existing telecom wiring scheme...this connection includes the use of 66 blocks and a patch panel.

There is a reason why you can buy cat5 e and cat 6 110 blocks.

Many years ago I did a very large wiring job for a mega church. They did not budget enough for the wiring so I installed cat5 and split it for voice and data. The phone system was 2 pair at the time. I contacted Allied Telesyn about using thier hubs (this was before switches) and what they thought of me splitting the pairs. They said that was what 10baseT was designed to do.

I punched down all the cables on cat 5 blocks and used cat 5 jumpers to patch panels. It worked just fine.

Now a days I don't split pairs unless I absolutly need to but when I do, I usually use an adapter made for this purpose. I have never had a problem whether its two computer connections or one tdm phone and a pc.

Of course splitting does not work with typical gigaspeed which does require all four pairs.

its a TIA/EIA standard I don't believe 10baseT was designed to run on "spare pairs as I recall it was separable cat3 also with the same argument about the "spare pairs "

most customers around here went from coax to cat5 wasn't a lot of 10baseT

i was involved in some early discussions on the TIA cat5 standard and I don't recall dual use even being on the table

10baseT was introduced back in 1990 to take advantage of existing twisted pair (thus the T) telephone wiring. My MCSE study guide says it was introduced to take adavantage of "extra installed pairs". Now does this mean extra installed pairs confined to one jacket? I don't think so. Previous to 1990 my customers didn't ask for an extra cat 3 run to be installed in an outlet in case some new data wiring scheme might be invented one day. Back then I was pulling coax or using baluns with existing spare pairs. Later I converted those "unused pairs" to 10 baseT. Siemon came out with a slew of modular y adapters for just this purpose. They still offer them. You can split for one voice/one data or one voice/token ring or two 10baseT. They officially only meet cat 3 standards but work just fine on cat5 and cat5e up to 100mbps. I know cause I use them a lot when circumstances dictate it and I have the equipment to test and verify the speed.

Twisted pair was invented to prevent crosstalk between the seperate wires. Logically you would have to conclude that splitting cat 5 would be less troublesome than splitting cat 3 considering that it has more twists per inch.

My point is this. Using what you have including splitting pairs has been done for a long time. It works and when it is the only choice you have it is a good thing it works.

there is a lot you can do that "works "

when installing a cabling professionally its best to stick to the standards rather than do what may "work" ..just my opinion

I suggest its not cable manufactures who are driving the standard but rather industry pros

or you can do like Tim and show up with a Gaylord of coat hangers and a pair of lineman's pliers :p

Well I respectfully disagree..The cable companies do push wire at us. They were pushing cat 6 before the standard was even a standard. There was big round cat 6 with a foam core and flat cat 6 and if you were unlucky enough to use that junk you found out real quick that a bundle of flat cat 6 picked up so much RFI as to become worthless. Lucky for me I never used it.

I happen to be a very sucessful cable installer. And the reason is I get the job done and don't force my customers to buy things just to meet a certain standard when the real standard should be...can you get it to work without having problems later. That is the standard I try very hard to adhere to. I suspect that you also do the same thing.

What I was hearing in the origanal question was: Can you use Cat5 spec wiring for both voice and data without compromising the integrity of the voice or data? So in this scenario I am assuming he doesn't need all the conductors for data and he is asking will using the spare pairs for voice cause a problem. The answer is no. It will not affect the speed or interfere with the data if this application requires less than the four pairs. Cat5 has on average 3 twist per inch (although each pair has a slightly different amount of twists per inch). As stated above it is designed to eliminate cross talk even with the higher frequencies. Many times buildings are prewired with Cat5 and that is all you have to work with. If only two pairs are being used for data (10BASE-T or 100BASE-TX)then it will not cause any problems to use the remaining pairs for voice if the wiring is free of faults and the pairs are balanced.

Thank you westflgator (my Daughter would say Go Gators!) for bringing us back on topic and I offer you a big welcome to the forums.

Thanks Derrick, this is a great forum that I am glad to have found. There is so much knowledge and resources available here.

GO GATORS!!

Its is easy to do with Bix using pig tails. You can run 10Base-T and phone over Cat3 wire if you had too. If you got a house built back in the 80's and you can't re-cable it ! But you have 3 pair you can still have a hard wired home network.
Cheers:
I am Canadian and love bix :toast:

Working in healthcare has given me a new appreciation for following standards. And that's saying a lot, because I've always been a stickler for following the standards.

We had a facility cabled recently where the installers didn't follow the industry standards and didn't follow our specifications. They used electrical staples to secure cables in the attic, had too much jacket stripped off at the terminations, too much wire untwisted, etc. Some of these runs actually certified, but there were lots of dropped packets and the computer would frequently drop off the network altogether. Sure, you had a link light at either end, but there's a hell of a lot more to it than that. The installers were sent back out to re-terminate, remove zap straps and staples, and certify. While you cannot undo physical damage to a cable, the difference was noticeable. Not a big difference in the test results, but from a practical standpoint, the computer stays connected to the network and the transmission errors have dropped way down.

At one of the hospitals there was a cable that we suspect was damaged during some unrelated construction work. The cable had a marginal pass with the certification meter, with return loss being the worst offender. That's a good sign the cable was probably crushed or kinked somewhere in the ceiling. The reflections were causing collision errors which a normal workstation was able to deal with reasonable well. Unfortunately this drop was used for a diagnostic imaging workstation, and the software was very sensitive to latency and transmission errors. Almost every time the software tried to communicate with its server it would time-out.

My point here is that just because something appears to work when you do something like splitting a 4 pair cable for voice and data, or running data over a 3pr Cat3, it doesn't mean it's working very well and it certainly won't work in all situations. It's like using the "boot" many cars have as spare tires. Sure you can get from point A to B, and you can probably get away with driving faster than the rated speed. Nobody here would want to drive on that boot any longer than absolutely necessary. You wouldn't let a tire shop to put 4 of those on your car and tell you it's good enough.

If you're doing something as a professional, you do it in a profession manner. I split a cable for two computers in my house, so yes, I'm very much aware that it is possible. I would NEVER do this for a customer, and I would never let a contractor get away with doing this in one of my facilities. It either gets done properly, or it doesn't get done at all. Even a house built in the 80's can be cabled properly. It just takes the right expertise, tools, time, and materials. If someone isn't willing to pay for the work or the don't want to see any raceway, then perhaps they should stick with wireless.

If splitting pairs should never be done, then technically should POE run on a seperate cable all by itself as well? POE uses a "spare pair" Just something to think about.

Also I don't think it is quite fair to compare using spare cat5 pairs for a second device to putting staples through a wire. The first does not meet a volunteer standard, the second is just plain careless.

Never is a strong word. I have been in business for twenty years plus now and I used to say never a lot. I don't anymore. For example: one of my oldest and largest accounts wanted a printer connection in a cubicle in the middle of the room where the cables are fed from an underground conduit. It is stuffed full of cat5 and cat3 cables. There is no way I can get a new cable in the conduit without pulling it with a lot more than 25 pounds of pressure even taped to a snake. I will damage the cable and possibly damage the ones already in the pipe. I explained this to the customer. They understoodd but they wanted the printer and wireless is not an option. I told them that it wasn't standard practice but that I could use an adapter to split the pairs at both ends without modifying the cable itself and thus provide them with an additonal 100baseT connection. This was not a code violation, just a violation of a volunteer standard. They said go ahead. Five years later the printer cat5 connection still works, as do all the other connections in the cubicle, with absolutely no problems.

Sometimes I think we installers protest too much and we sometimes loose site of the big picture...make the customer happy!

Make the customer happy BUT do things the right way whenever possible, and explain to them it may not work right if you have to deviate from the established way of doing it.

Jeff that is exactly what I have been trying to say since this thread began. westflgator provided the OP the answer to his question. Me...I just ramble on!

I love it when a plan comes together!

Everything I have ever seen or heard:

10 or 100 = Cat 5 cable - uses 2 pair

1000 = Cat E or above using 4 pair.

Lets be honest here guy's....You just plain shouldn't do it...Unless your at home working on a project for yourself...almost out of beer and the game is about to start...Other than that get busy and run another Cat 5...Problem solved. :toast:

Come on now. I respect everyone here and I think this has been a really good discussion. And with that in mind I have to say that to say never run two devices on one cat5 e is like saying that a telco should never put two pris on the same copper pair cable. Sometimes you just have to do what you have to do, when another run isn't possible.

Also, its okay to run up to 44 volts DC of POE over one or two pairs of a cat 5e with no problem but a second ethernet connection or a 24 volt or 48 volt analog connection instead of POE is a problem? POE is designed to use in place of USB because it is cheaper than using USB repeaters. I am not convinced that a tdm phone or second ethernet (up to 100mbps) can be more detrimental to the cat5 run than 44 volts dc.

I also know that some tech companies such as Simplex Grinnell (a Tyco company) are requiring their techs to install two voice and two data jacks to each workstation using 2 cat5e cables not four. They seperate the pairs at the patch panel end and at the workstation end. This has become standard practice in their offices and so far it seems to work fine.

It might work fine til they try POE or gig. Some consultant probably wrote a bs spec to save money.

Absolutely, there is no argument about that. If they ever want to use gig or POE then they will lose a large number of ports if they reposition the pairs, that is a given.

The way twisted pair works, a DC offset really isn't a problem. A DC voltage will create EMF, and that will induce a voltage in nearby conductors. Because the DC is constant, the voltage induced on both conductors of a twisted pair will be virtually identical. If you add one volt DC to both conductors, the difference in voltage between the conductors doesn't change, therefore we have no ill effects from the DC. When POE shares conductors with the Ethernet signal, all you are doing is letting the signal ride on a DC offset. This is stripped off at the powered device, and does not change the signal.

An analog phone has a DC carrier, low frequency ring voltage, and low frequency audio. Of all the things that can share a cable with Ethernet, an analog line is going to be the safest.

Digital phones to the best of my knowledge are operating at well under 1Mhz. They would have a greater chance of causing interference, but still not likely to be a problem under normal circumstances.

Two data connections on one cable is the most likely to cause a problem, since you are putting two signals of the same frequency into such close proximity. It's like a mix between crosstalk and alien-crosstalk. 10Base-T would be less susceptible than 100Base-T. If both computers have a relatively light load you reduce the likelihood of problems.

AMP does have their ACO product which does allow you to split a cable for two 100Base-T connections. They were popular with government offices here in town back in the 90's. I wired some of those government offices so I suppose I'm as guilty as anyone else of splitting data cables. (I was young, didn't know any better, and I can blame the government.) I'm sure that product made sense before Gigabit, but I don't see why anyone would want to intentionally prevent their infrastructure from supporting Gig now.

At the very least, these ACO inserts were engineered for this specific purpose. If a cable must be split, this is how it should be done. Peeling back the sheath and splitting the pairs between two keystone jacks is absolutely going to have a negative impact. It might cause issues with additional noise, return loss or NEXT. You really won't know because you can't properly test the cable.

Cables are built with specific geometries for a reason, and when that geometry is compromised, that is when we have issues with EMI,RFI and crosstalk. If you kink a cable, the pairs are spread apart. This reduces the effect of the twisted pairs and that exact point is where noise will be induced on the pairs. If you have two Ethernet signals in one cable, and that cable is kinked or crushed, the crosstalk between those two signals will be much worse than if they were in separate cables. Physical separation is important.

There are situations where splitting one cable for voice and data is a reasonable solution, even if it isn't the last resort. However, I've never seen a situation where a switch couldn't be used rather than splitting a cable for two Ethernet devices. Either way, this is a decision that should be left up to the trained professional. I'm not trying to tell the pros anything they don't already know. This is aimed at anyone who may simply gloss over the cautions, and decide this is an excellent way to save money on cabling. Being cheap is not an excuse to split a data drop.

Clinton, thanks. I think you summed up this discussion quite well.

i think you could make a MDF Cat5e blocks in central office,and make VDSL splitter on it,then, make the ADSL splitter in home.
hope this would be helpful for you

Ok, after two pages of discussion, somebody tell me why data cables like CAT5 have 4 pairs? That's 50% of the copper you are paying for that isn't used. Very expensive filler. And before somebody says they maintain the transmission characteristics of the cable I say baloney. This is wire that is open on both ends.

My opinion is that they are there to put money in the manufacturers pockets. It started with CAT3 which had applications for all 4 pair and they just ran with it.

-Hal

More to the point: 2 PAGES and 2 WEEKS. If you're gonna steal pairs, do it! If you're not, run new cable!

Hal, you need 4 pairs for gigabit ethernet and power over ethernet.

You need the 4 pairs so you can steal two of them for the phone and the fax machine.

Now, let's get back to REAL telephony and discuss why there are 25 pairs in a station cable for a 1A2 6-button set.

Originally, the 6 button (5-line) phones were installed using 16 pair cable. Then the 10 button (9 line) phones were released requiring 25 pairs. And still needed shared LG & A1.

Four pair CAT4, (yes, there was a CAT4) CAT5 and CAT5e was being made way before POE came into use. Still POE is only an extra one pair. Gigabit requires CAT6 and all four pair.

You need the 4 pairs so you can steal two of them for the phone and the fax machine.

Well, that actually may be the reason and BICSI and other butt head IT "authorities" wouldn't hear of it. But I kind of like my idea that the whole thing is BS from the cable manufacturers to get more money out of your pockets. Otherwise they would make 2 pair CAT5e.

-Hal

Ha, forgive me for being a PITA, but while I agree 100% with your post, the gigabit issue needs to be clarified.

The gigabit ethernet system that "won" is 1000base-T, which will run on plain old CAT 5e cable, but does require all four pairs.

It is 1000base-TX which requires CAT 6. 1000base-TX uses only two pairs, but it lost the race and is not seen much.

10 gig ethernet requires CAT 6e, making CAT 6 the answer to a question nobody asked.

My point being that I believe CAT 6 is an even bigger ripoff than the two wasted pairs that results from using CAT 5 for 100 mbps and lower ethernet. At least those extra pairs can be used for something...

Jim
**************************************************
Speaking from a secure undisclosed location.

We have gig throughout our building with all Cat 5e cabling. Works like a charm!

The 1000Base-T standard came out around 1997 I believe, and they would have been working on that for several years prior. It would make sense then for the cabling standards at the time to look forward towards adoption of the new technology which would require 4pr cable, even if the technology of the moment did not need more than 2pr.

Buildings that were properly wired 10 years ago using Cat5e will support Gigabit and POE+ without any need to retrofit the cabling. That's the beauty of following standards. I think we need standards to have the longest life-span possible, and that means building the capacity to use technologies that we don't have on the market today.

A correction to my earlier post: 10 gig ethernet requires CAT 6a, not 6e [no such thing as 6e].

CAT 6a is also called "augmented" CAT 6.

Of course, if people really need to move data at 10 gigabits per second, they should probably be using fiber instead of copper.

Jim
**************************************************
Speaking from inside "The Rock."

Hal, I remember CAT4 fondly. Bought several dozen spools of it from North Supply. AFTER CAT5 became 'The Standard'. They were 'fire saleing it'. They were selling it for 1/2 of the going price for CAT3. Too bad they didn't have more!

The 1000Base-T standard came out around 1997 I believe, and they would have been working on that for several years prior. It would make sense then for the cabling standards at the time to look forward towards adoption of the new technology which would require 4pr cable, even if the technology of the moment did not need more than 2pr.

Yeah right. Nice try trying to give the IT industry the credit. :rofl:

Where did the 4 pair "standard" come from? Remember, there was 4 pair in the CAT zero days. I think you will find the answer if you look at the Bell System/AT&T 568B standard that was probably written for the old Merlin systems. That was the first use of a 4 pair cable.

-Hal

poe uses the brown pair
telephone uses the blue pair
10Base-T uses the orange and green pair

And their is more than one way to skin a cat5

Bix did it

568B is WECO! There can be no other explanation. The Merlin was introduced in 1983. Executone had a Triad K410 4-pair system at about the same time, but it used the USOC wiring code and as we know, USOC was not adopted for data use.

Good ole' Western Electric...where would we be today without all the suff they provided? 568A was their own private standard. I just loved wiring two pair usoc phones to the white/blue white/grn pair.

"Where did the 4 pair "standard" come from? Remember, there was 4 pair in the CAT zero days. I think you will find the answer if you look at the Bell System/AT&T 568B standard that was probably written for the old Merlin systems. That was the first use of a 4 pair cable."

Actually, it was about a decade before the Merlin systems came out. 568B evolved from WECO's propriety wiring designed for their MET sets that were used on their Dimension PBXs. Later uses came into play on Horizon systems and even for fifth line conversions on ComKey 416 systems. Yes, Western Electric invented it for sure, but someone else managed to get the credit.

Just to keep the archives straight, so that adventurous web surfers from the 24th century will still be able to get their ComKey 416 systems up and running:

The 5th line on a ComKey 416 system requires three-pair wiring.

Ahh yes. That would explain that reel of 3 pair cable that I used to have many years ago.

-Hal

For the record I wasn't trying to say the IT industry invented 4pr cable, merely that it would make no sense for the standards bodies to bother with a 2pr standard when the new Ethernet standards would require 4pr. The point being that the standards bodies need to look forward to compatibility with new technologies, and not create minimalist standards that only work with current technologies.

In the years that I did a lot of SL-1 work we ran nothing but 3 pair cable - voice, data, power. Same for the GTE Omni and, as I recall, the NEC Electra 100.

Sam

For the record I wasn't trying to say the IT industry invented 4pr cable, merely that it would make no sense for the standards bodies to bother with a 2pr standard when the new Ethernet standards would require 4pr.

And I was merely pointing out that at the time the "4 pair standard" was adopted there was no reason to believe ethernet would evolve to more than 2 pair. The "standard guys" just glommed onto 4 pair because there was a 568B WE standard already in use at the time.

Matter of fact the recent use of the other two pair probably came about because somebody said "Hey, lookie here. There's another two pair that isn't being used. Lets use them for something". :idea:

Otherwise you can bet your bippy cable manufacturers would figure out a way to run 10 Gig ethernet on 2 pair just to make UTP a viable alternative to fiber.

-Hal

And they might, yet.

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Ring voltage might actually be more of a problem than what I assumed above. If I have some time to kill one of these days, maybe I'll set this up as an experiment...see what actually happens.

The Fluke certification meters can test for impulse noise, which does not come into play for certification. If transmitting ring voltage down the same cable does cause a significant problem, my guess is that it would show up as impulse noise.

Please let us know the results of your research.

This is the 21st century and apparently that is what Cat5 was originally designed for! Weather you like it not its being done daily and if you know how to install it correctly you can appreciate it. There is 100 pair phone cable behind my house it was installed in 1980 on poles, it has alarm circuits, ADSL, pots lines and what ever the phone company has running through it. Around supper time everybodys phone is ringing and everybody is on the internet and everything is running through that old 100 pair. There is no noise on my line and the Internet is OK. My house is networked on one cat5 since 1998 and it works great and looks great and cost half the price of running two separate networks ...
Touche

OK, you are right about the three pair wiring requirement, but it did use a D8W line cord and an 8P8C connecting block with WECO wiring (A.K.A: 568B). I was close.

Yes, you are close enough.

Way back in the beginning of Structured cabling systems AT&T came out with a 21 pair cable which included 7 groups of 3 pair, each group was wrapped with mylar and then the 7 3-pair groups were formed under the cable sheath. It was meant to terminate on a row of a 110 block using 110C-3 clips. The wiring system didn't last long as far as the market goes, eventually replaced with 4 pair cat 3.

Note to Sam - This was for Thompson McKinon down on the wharf, Forest installed it about 1986 or 87

Thanks Joe. I remember seeing it and scratching my head. Why not 8x3? It filled the blocks better! I was at Lenox Hill Hospital in those days and we had just finished wiring 3,000+ stations - all with 3 pair. We had 2500 sets for the patients,GTE Flashcomm (analog SLT sets with hold and flash) and Eagle electronic Key for Admin. All sitting behind a GTD-4600 CO.

For Data we used the same 3 pair with Baluns for IBM cluster controllers.

From there I went to Irving Trust. Same set up. 3 pair was all we needed. Electronic Key was either ITT or Eagle. Easy to run, easy to term, easy to use. 8 cables on each side of a 66 block. I guess it was around 1988 that we started experimenting with Cat 5 - but just for Data. Voice was still 3 pair Cat 3.

Sam

half price ? cable is the smallest cost in the equation , the labor is roughly the same to pull one or two cables . termination costs ? your still making two terminations using two jacks .

just how much Ethernet is running on that "old 100 pair" ? (we are talking about Ethernet here )

look at the "ugly work thread here , most of that stuff "works great" if you where to ask those that installed it

there is nothing new about the concept , I recall a distributor in the early 90's touting the adapters and stating two Ethernet drops per cat5 cable or Ethernet and phone on one cable

what you do at your own house for yourself or what may be done in a existing situation with no other practical choice is one thing but to advocate and practice non standard compliant new installations as a "cabling pro" is just plain wrong and a poor practice in my opinion

there is a lot of poor , non standard compliant work being "done daily "

Good points. I may have to do this for a customer of mine. They moved into an Old building with existing cable. I am afraid to open the ceiling tiles due to possible Asbestos used. I think I will just use the Brown White off of the data cable for the voice. :db: