10base-T & POTS in same Cat-5 cable?

Actually, they were likely 60 mA or 20 mA. Incidentally, I started my career overhauling teletypes. I worked on M32, M33, M28 & M35, among others and my first computer printer was a M35 ASR, which I bought surplus from my employer.

I'd have though 50 Hz would have been the problem, when Europe was in view. ;-)

Multipair telephone cable is twisted pair, nowhere near the level of twist you'd find with data cable though. The only non twisted pair you are likely to find on the telco side is old single circuit drop wires.

There isn't anything wrong with paper as an insulator.

Though typically you have to use compressed air to keep water out if the outer jacket springs a leak.

When you have people arguing technical details they don't understand, pedantic attention to *correct detail* is extremely important. Hence, while it may be true that pedantic is not usually considered desirable, in this thread it has been essential.

The subject line does *not* provide a definition for either data or voice. 10baseT and POTS are specific, not general, forms of each. If you want to say 10baseT and POTS, say it. Regardless,

*you* have discussed several other forms of data in this thread. (Such word games are exactly why it is necessary to be pedantic.)

Regardless, you are still wrong. The impairments are the same, all that differs is the intensity; and understanding the mechanism, which is the "truism", is important.

It does. And in a properly installed and functioning example the interference will be below the critical point, and the circuits will be deemed to be functional. However, saying, for example, that 20 Hz ringing on a different pair will not be a problem in such a circuit is vastly different than saying 20 Hz, because it is on a different frequency, can't ever interfere with 10baseT.

Total nonsense.

The cable pairs are twisted. In fact each pair in a bundle has a _different_ twist, to prevent any two of them from getting too cozy. Then the whole bundle of twisted pairs is swirled. And then all of the bundles are swirled within the sheath itself. That is the way multi-pair cables have been manufactured for many many decades.

Most power influence *is* crosstalk, between a comm cable and a power cable. Anything that helps one will help with 60 Hz will also help at VF and above, and as we've both noted previously the effects are greater at higher frequencies. Which means it is exceedingly difficult to do something which helps at 60 Hz and does not have an even greater effect at VF or above.

Regardless, even at VF twisted pair is *vastly* better than flat satin non-twisted cable. It is not a "marginal" difference.

Nonsense. I don't even know where to start correcting that, because none of it makes sense.

When the error rate significantly exceeds the design BER, what happens is... the error rate exceeds the design BER. That doesn't cause a catastrophic failure. Typically a progressively higher BER will cause some degradation of the data throughput for certain types of protocols, TCP being one. IP may or may not be much affected... which is to say the effects on UDP will be different than the effects on TCP. That is because UDP is not a "reliable" protocol (and thus will be greatly affected) and TCP is (and will merely be slowed down).

A BER of 0.1% strikes me as exceedingly high, given that the target on DS1 facilities is 1 x 10e5, and you are talking 100 times that. Given that most DS1 facilities run more like 10e8, or another thousand times less, I'd say that a split pair causing a 1x10e3 BER is in *extremely* bad repair.

What I said is still true and what you said was not.

If you split a pair using CAT3 or CAT5 for 10baseT or 100baseTX, there *is* going to be a problem. A short length measured in feet will work with 10baseT, but for 100baseTX it will be measured in inches. Both are necessarily the multi-pair example I described above, with or without a POTS circuit present.

Crosstalk *is* an external field.

It is *exactly* the same thing at the end of the cable where a differential detector is expected to make use of common mode rejection.

So?

Exactly. And that will lead to both phase and amplitude distortion which differs between the two wires of the pair, and that results in amplitude distortion for the facility as a whole.

For an ADSL loop. Do you understand that no doubt means that a similar length of CAT3 with a split pair stretched out in the same place would work equally well?

So? It might be, but it might not be.

Then why were you babbling about having only one pair involved?

More nonsense.

Wired that way there are two split pairs, period. Whether POTS is put on the second split pair or not will make little difference to the 10baseT using a split pair. Putting POTS on

*any* pair, split or otherwise, in that cable is going to be a problem for the 10baseT signal on the split pair. Which is to say, if the pair is split, *any external field* will induce a current and cause problems.

I have no idea what nonsense you are referencing in regard to a Left Hand Rule and crosstalk cancellation vs. amplification. And I hate to think what it is you mean...

It is pure folly. Abject foolishness. (Am I clear enough?? :-)

My bet is that you have no idea whether is works well or not! I saw a guy "splice" some CAT5 once. It was a 175' or so run and at about 125 feet the roll ran out. So he got another roll and literally tied the two cables physically together with a knot and then split out each pair and twisted the wires together and taped them up, and finished the run.

It "worked"! I told him, as did a couple other people, that is was too ugly to live and that he ought to be shot. Not to mention that I didn't believe that it worked anyway.

You know, it "worked" just fine. The PC it went to could access the LAN. What can one say, eh? There was this nagging problem that that PC for the next 6 months would hang, sometimes several times a day. And when IT tried to work on it remotely they usually could, and nothing would be wrong, and sometimes couldn't get into it at all.

We finally got fed up and found someone with the authority and the understanding of cable, showed him that splice and he "authorized" the culprit to run another cable for that PC.

On an Ethernet, particularly using IP, it is relatively difficult to know just how bad some of these things actually are...

Exactly. David Lesher and I both had comments previously about doing exactly that. But given the strange ideas you have about how all of this works, I can't see what you are doing as an "informed" risk.

No doubt.

Not even that is a good guide. Since an installation may have been made long after the building was constructed. Especially with overhead drop wires. If it looks like an old piece of cable is causing problems it's going to get replaced by more modern cable.

Both ISDN and ADSL are specifically designed to run over existing cabling. It would be incredibly expensive to have to replace all the underground multicore.