Telephone wiring

[justadilettante]

I just switched to VOIP telephone service, and had to run an outside line from where my cable service comes in to where the old POTS line comes in. I used outdoor rated shielded cat3 cable and I've got it working great, but I've got a couple of questions because I really, really like to know WHY I'm doing stuff.

Many years ago I did the telephone wiring for most of my house, and although I connected all 4 wires I thought that only 2 carried the line. So, 4 wires = 2 lines. Is it true that now each line uses all 4 wires? If so, what's different?

Looking at my wiring, I see that my old outlets have only 2 connectors, whereas the new outlets I purchased have 4 connectors. Should I replace my old wall outlets? Is there any benefit if the voice quality is already good as is? Do my telephones care?

Finally, is the old, thin telephone wire still considered adequate? I'm not about to rewire this house, but I'd like to know if I do this again in the future.

Thanks -

[RBM]

Typical telephone wiring today is 24 gauge. You only need two conductors per line. If you connect more pairs , you could connect them to more lines

[Jim Redelfs]

Correct.

Correct.

No.

No, unless they are not working or you need the practice.

No.

No.

Yes.

24-gauge is the current standard. There is plenty of 26-gauge out there but, other than its propensity to turn into a rats nest in a ready-access cable terminal, it is technically sufficient for POTS.

I discovered the other day that Menards is STILL selling *GARBAGE* telephone cable. It is white-sheathed 3-pair 24-gauge with (apparently) NO twist. The "pairs" are red/green, yellow/black and white/blue.

Just to verify my suspicion, I connected my butt set to one pair then applied my "toner" (tone generator) to another pair. The cross"talk" was so bad it was almost like a direct/hard connection. Absolute trash for anything more than one line. Talk about "let the buyer beware". Sheesh! :(

[justadilettante]

Thanks - I didn't think I should believe everything the wire guy at the local boxstore told me!

For my info, why do you care about the twist (referring to your response)?

[Brian O]

ready-access

The twist he is referring to helps to create an electromagnetic "shield" and helps to cut down on the crosstalk he is talking about. B

[Bert Byfield]

Phone lines use two wires. The second pair of wires was in olden times used for an a/c connection to a phone accessory, but that never got very popular. Some people used the second pair for a second phone line. Usually the second pair is unused.

[hallerb]

I helped a friend upgrading to DSL, and found some old still plugged in AC adapters for lighted phones buried in cielings of this over 100 year old home.

The upgrade was a nightmare since verizon did NOT like AT&T supplying DSL on their network. I swear verizon did something intentially:(

I finally plugged the modem, directly into the NID and it wouldnt work dependably, then tried my working modem from home, it wouldnt work either.''

A week later my friend got verizon and it worked flawless....

[mm]

I always thought the 2nd pair of wires was there primarily for a second line or any other use that might be thought of in the future, the same reason my house built in 1979 has something like 6 pairs of wires. Not because I'm going to have 6 phone lines but because the phone company plans ahead. For the same labor, they can install more than 2 connectors.

[Mark Lloyd]

Phone lines use only the center 2 wires. You might have a use for additional wires at some time, and be glad you connected them.

All the plugs/jacks are made to have space for 6 wires. I noticed that the stuff Lowes's is selling now has all 6.

No need to if they still work.

[Mark Lloyd]

One apartment I lived in for a year or so around 1980 has a plug-in transformer with its secondary connected to the extra pair (black/yellow) or the phone wiring. It didn't seem to be used for anything any more, but according to what I heard, it used to be used for a lighted-dial phone.

BTW, for the 3-pair cable I've seen the additional pair is blue & white.

[Jim Redelfs]

The "twisted pair" technology was developed in the 1920s, I believe.

In basic electricity, we learn that a conductor carrying a "flowing" current generates an electromagnetic field around that same conductor. This is the basic principle behind electromagnets and electric motors.

A phone line (a pair) generates an electromagnetic field. Another phone line (pair), also generating its own electromagnetic field, when run along side another, working pair, will inductively "cross" with that pair after only a few feet of side-by-side operation.

It was discovered that, if each pair is twisted (perhaps 2-3 full turns per foot, at least), and the entire cable is then twisted, the electromagnetic fields "cancel out" one other.

You'll notice that old telephone cable has minimal twisting, but it's there and is sufficient for POTS (Plain Old Telephone Service) including DSL. Modern Cat3 cable is noticeably more twisted and Cat5e is twisted even more. This is to improve the performance of the cable for data purposes.

The garbage wire sold by Menards has NO (zip, zero, nada) twist and, as such, is unsuitable for anything more than ONE working POTS line - the extra pairs/copper is just wasted. Simply put, it is substandard wire. If this were electric cable, the NEC/NFPA/UL would jump on their @$$ in a heartbeat.

There's no code or legal requirement for minimal specifications for low voltage communications cable. As such, Menards is getting this wire from the cheapest vendor (no doubt China) and foisting it on unsuspecting DIYers that probably believe they are installing "the good stuff" when finishing their basement or home office. It's trash and Menards should be ashamed.

[Jim Redelfs]

Correct.

Additional pairs are for additional lines, dial light current (obsolete) and, in the case of a failed pair, a SPARE pair that can be used.

The Bell System defined the term "overkill" as swatting flies with a sledgehammer.

Even back when there were 2, 4, 6 or even 8 subscribers on a SINGLE pair, they wired homes with two pair cable.

In the 60s and 70s they switched to 6-pair cable. (Serious overkill.)

Then, for 15-20 years, they backed-off to three pairs. The standard now is

4-pair and likely to be a standard for a LONG time.

It takes only a pair of wires to make a phone work. So what are all those extra wires for? They're just... EXTRA!

[Nate Nagel]

I was willing to believe you right up until that last sentence... after that I know you are pulling my leg.

nate

[Mark Lloyd]

The house my parents bought in 1969 (it was a new house then) had the phones wired with 6-wire cable. There was just one active phone connection (hardwired then, in the kitchen), but wires were run to the bedrooms so jacks could be added. It did not use the standard colors. I remember when I tried to add another jack, I had to test it. The wires were: green, green stripe, blue, blue stripe, orange, orange stripe. I forget which ones were in use.

[Thomas Horne]

Mark Those are indeed standard colors. Cables such as 3, 4, 25, 100, or 1000 pair use a repetitive colour code based on a primary and secondary colour. The pairs are twisted together individually. There are only five primary colours and five secondary colours. The 1st pair would be White-Blue , the 2nd would be White-Orange, etc. The standard secondary colors used in three to five pair cables are blue, orange, green, brown, slate. If the original installer followed the drill he used the blue and blue white pair for the first line. The white is the primary color that identifies the first five pairs of the cable.

-- Tom Horne

[Mark Lloyd]

Yes. I learned that LATER. At the time, the only standard I knew about was red/green, black/yellow (and maybe blue/white).

[Mark Lloyd]

I think I understand that system now. It would allow 25 unique combinations. What do you do for more than that?

Anyway, this is not the same as what I found. This was just a 3-pair cable, each pair has a solid color wire (green, blue, or orange) and a white one WITH A STRIPE of that color. This house had just one line. I forget which pair was used.

BTW, I have some new phone wire I got at Lowe's in October. The colors are white, black, red, green, yellow, blue (that's the order they're shown on the wiring diagrams on the package).Several places they said the colors to use for phone lines were line 1: red/green line 2: black/yellow, line 3: white/blue. The packaging for the jacks mentions an alternate code, which is like what I found. I think your system was an additional alternate, but I don't remember.

[Jim Redelfs]

The first 25-pairs are spiral-wrapped in a white/blue "ribbon". The next

25-pairs are similarly wrapped in a white/orange ribbon. The third group (of 25-pairs) is wrapped with white/green ribbon. The ribbon bundling the 25-pair groups follow the same color code sequence as the first 25-pairs. This works up to 600-pairs. Beyond that, the sequence starts over with the addition of a red ribbon to every 25-pr group. These are known as "super groups" to indicate the count starts with pair 601.

You should see what it looks like when a backhoe brings up a 900-pair cable the hard way. Thank God I'm not a cable splicer. Call before you dig.

BOCs (Bell Operating Companies) used 3-pair for probably 15-20 years. The white/blue pair was used for line one and connected to the red/green posts on the jack. The third pair (white/green) was used for dial light voltage and laid down to the yellow/black posts. White/orange was just spare unless it was used for a second line.

That describes exactly the garbage cable that Menards sells. I would hold out for cable rated Cat3. I'm guessing there is no "cat" rating on your cable.

However, unless you're running more than one line on the cable (requiring only ONE pair), rating or twist doesn't really matter. With tight/good connections and insulated from each other and ground, one can run a POTS line on bailing wire and coat hangars. More than a few DIYers do.

[Mark Lloyd]

I've never been in such a situation (having to fix a broken 900-pair cable). I can imagine what it would be like.

Several houses were built around there (Denton TX) at that time. I don't know about the cable, but I do remember hearing other people mention nonstandard cheap stuff being used.

I also don't know about the quality of the wire in the house I live in now. It was built around 1969 too and has black/red/green/yellow wire. I don't know about twist, and never had a second line using it. I have had a second line, but that used separate, newer wiring.

[Thomas Horne]

Since the primary colors are white, red, black, yellow, and purple the first twenty five pairs would have a white blue wrapper. The second would have a white orange and so fourth. The sixth would have a red blue wrapper. The seventh would have an red orange wrapper. The eleventh would have a black blue wrapper. The twelfth would have a black orange wrapper. So you have twenty five pairs times twenty five wrappers for a total of 625 pairs. I never learned what the code is after that.

What you describe as the colors you found is the first three pairs of the color code system. All three pairs had the white primary color and one of the first three secondary colors. As I said before if the installer followed the drill; i.e. used standard practice; The pair that was used for the first telephone line was the White with blue stripe and blue pair.

The type of telephone wire that uses solid colors up to three pairs is called JK or station cable. It usually has little or no twist to it so if long lengths of it are used for two or three telephone numbers it is prone to cross talk.

-- Tom Horne