atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring More noob questions - House Wiring

Not really sure if this should go here or in Cabling, so I figure I'll post it here and get corrected (I do apologize if this is the wrong spot).

I was out and about today, and decided to pick up a cheap analog line tester. I tested a couple of jacks that are working, and the tester indicates that the polarity of the line is reversed. Being new to all this, what does that mean? Is it a bad thing?

Next part of that is I was playing around with the butt set on a jack I was rewiring (swapped it out to match the room). That brought up two questions: It doesn't matter what order (tip vs ring) that the set is connected to the line does it?

Also, I don't remember which clip I had connected first, but I was listening to the butt set, and when I clipped one clip, I got a hum in the receiver, but when I clipped the other, it disappeard. Pressed the monitor button, and got dial tone. Curious as to what the deal there is too..

Thanks!
Scott

I moved this to cabling since the major question is about the wiring.

The polarity being reversed is no big deal on POTS lines. There was a time when it was an issue, if you put an older Touch Tone phone on the line you can't break dial tone with reversed polarity. So to you other question it doesn't matter to todays phones and other dial tone equipment where tip or ring goes. I think you'll find most of us want tip on tip and ring on ring. Why not do it right?

The hum you heard when you only had one clip connected on your butt set was impedence mis-match, that's why it went away when you put the other side on.

Another way to check polarity of the line is put one lead of your butt set to ground and the other to one side of the line. The line side that draws dial tone is the ring. We always did this in the old days at the protector to make sure things were straight inside.

Yep, reversed polarity doesn't bother a phone line anymore.

Ground Start Trunks (if anybody still uses them) require that polarity be kept straight.

How about payphones? Are they still ground start?

Sam

Thanks guys!

Since I'm somewhat of a perfectionist (and it'll drive me nuts), even though it doesn't matter, is it as simple as flopping the pairs around to correct the polarity? I checked all of the operational jacks in the house, and they all show up as polarity reversed, so I'm imagining that it's I'd just swap the wires around where the line comes in?

I was reading about ground start line seizure last night in the manual for the Harris Dracon TS21. Can someone explain it to me? Sounds like (based on what Sam said) it's not something that's necessarily used in residential wiring?

Thanks so much for the answers guys! My next step is to learn proper wiring technique, as I want to clean up the rats nest in my basement, then work on communications boards at both facilities I work at (all three if I can ever get to Kentucky again).

Yes it's just a matter of flipping the tip and ring, but if the tip and ring are laid down correctly in the jack check it at the DEMARC and see if it's straight. If not change it at the DEMARC.

Ground start are still use, though not as common as they once were, they were never used for residential. Their main purpose was to prevent glare on two way trunks. Thats when the incoming and outgoing calls butt heads.

I'm going to have to check it at the demarc, especially since it's all three jacks that are showing up as reversed.

Do any of you guys have a good reference for the coloring codes? For example, I know that on the jacks, it's red/green and yellow/black. Red I know is ring, and green is tip. Not sure about yellow and black.

Then, to confuse me even more, the wiring in the will is orange and orange/white and also blue and blue/white. Not sure what tip/ring should be on those.

Thanks!

Green tip red ring for pair one in a quad. Black tip ring yellow for second pair. W/BL tip BL ring for first pair in cable.

There's many sources on the internet for the color code, here\'s one

Perfect! Thanks Bill!

Just some FYI. Do not mess with the feed coming into the NID. That side belongs to the phone company. You can change the polarity on your side though.

On a lot of the circuits I've installed, the polarity was installed wrong at the NID. I guess it isn't technically a problem with any newer telephones, but I ran into a problem with an older (70s vintage?) rotary wallmounted phone that would get DT but couldn't dial out. I found that the polarity on the jack was reversed. As wrichey said, just flip the wires on the customer side in the NID to fix the polarity issue, if you know the polarity is wrong at the NID (use the test jack to verify, if the NID has one).

Polarity shouldn't be a problem with the old rotary phones, only the touch tone's.

-Hal

Actually, there was a field modification that could be made to rotary dial phones so that they would not dial out on a reversed polarity jacks. It was through the use of a diode inside the set.

I suppose that it is possible that some old 60's-80's vintage equipment out there that may still have this diode installed. Aside from this, there is no way that polarity would matter on a standard rotary-dial set.

Scott -

I mentioned Ground Start Trunks.

Trunks & Lines: The simplest definition is that a Line originates in a machine (a switch) and terminates on a phone while a Trunk originates in a machine (a switch) and terminates in another machine (a different switch).

For example: a circuit comes from the CO switch to a PBX. When you dial "9" from a PBX phone to get an outside connection, you're seizing that Trunk. When you pick up your phone at home to get an outside connection you're seizing a LIne.

The two circuits could be (and sometimes are) technically identical (they could both be Loop Start Circuits) though there should be some technical differences between them (a trunk should be more "robust" and durable).

Sam

I've got an 2500 set with a polarity guard installed...I guess the older stuff needed it.

Yes Jeff It did, especilly since the ability to call into bank accounts and other fun stuffed caused a battery reversal so that the dial would not work unless the guard was in place.

Like Bill wrote, always tip to tip and ring to ring. Doesn't matter with phones anymore but it does with data, and if you get complacent with one it's liable to carry over to the other.

Jack

You guys rock! Thanks so much for the great info!