Phone line volt/ohm meter check?

[paul cottingham]

I -THINK- its DC. I think if you have AC there, it may be an induced current. That is bad I think.

[Jerome Hanby]

The current from your Telco is DC. It starts out at 48 volts, but drops so it will vary based on your distance from the current source. Phone line is typically not shielded, so it's a great big antenna (especially if there are unterminated bridge taps) so it can pick up all kinds of induced signals (not too rare to find a phone where you can detect a local radio station in the background).

If you can disconnect tip and ring from the Telco tie in and short them on the house side of the connection, then you can use your ohm meter from any jack in the house and you should see pretty close to zero ohms (the wire will have some resistance). With that tip and ring connection open, you should read infinity. Unless you like testing the overload protection on your Ohm meter or buying new ohm meters, don't put it on the circuit if you are still attached to the Telco!

If you want to break the problem in half, take an old POTS (plain old telephone set) cut off the plug, strip back the wires and put alligator clips on tip and ring (green and red wires). If you disconnect the house from the Telco and clip onto the Telco connectors, you should have dial time and be able to dial. If you can't break dial time, swap the wires, some older DTMF phones are polarity sensitive. If all works there, you know it's not a Telco problem and you can work back into the house.

If you accidentally or otherwise short tip and ring while you are still attached to the Telco, don't worry about it. It's not a "nice" thing to do, but it's an old school way to busy out a telephone line. Much nicer to use a 600 ohm load, but not a disaster.

Of course, all of this is predicated on you having "normal" Telco service. If it's something "electronic" then YMMV.

I -THINK- its DC. I think if you have AC there, it may be an induced current. That is bad I think.

[Lee Schierer]

In our area, the phone company responsibility ends at the gray box outside the house, unless you pay for a service call or are on a service contract. The gray box has a regular modular plug that connects the house to the line. What I do to determine if the problem is in the house or outside is to plug a working phone directly into that jack outside. If the phone still doesn't work in the entry jack, I call the phone company to get the service restored.

[Jerome Hanby]

In our area, the phone company responsibility ends at the gray box outside the house

Same here, except our gray box is a cylindrical metal can with a screw holding it on at the bottom.

[Stephen Tashiro]

Until I purchased DSL from Qwest, the only phone box on the outside of my house said "Bell System". To facilitate DSL, a technican installed a modern box. When he did this, he left the old box in the line since he said its fuses would give me added protection. The implication was that the new box didn't give me such protection.

My friend lives in a large apartment complex, so I don't think he will be able to get to the phone company's box.

[Jim Koepke]

Until I purchased DSL from Qwest, the only phone box on the outside of my house said "Bell System". To facilitate DSL, a technican installed a modern box. When he did this, he left the old box in the line since he said its fuses would give me added protection. The implication was that the new box didn't give me such protection.

My friend lives in a large apartment complex, so I don't think he will be able to get to the phone company's box.

The installer likely left the old box because it was easier than removing it. I was a telephone installer a long time ago. Things have changed, but not so much so that workers will do more work than they have to. The line protection fuses require a ground wire. They really are not fuses, they are little arc gaps that will make a solid contact if the line is hit by lightning or other high voltage. This is to protect equipment and people.

If it is in an apartment, chances are it is a different type of wire coming into the individual apartments.

It could be a bundle of 6 pairs instead of the usual inside wire of two pairs. This all depends on how old the building and when was the last restoration.

The problem could be caused by another tenet messing with the wiring. Usually the telco box is in a convenient place for an installer to get to without having to find a manager.

Is this a new service, adding an extension or one that worked and stopped working?

jim

[Stephen Tashiro]

The box on my house was on my private residence. My friend lives in a moderately large apartment complex. His phone was working. Then it became intermittent. Then the line went dead.

Yesterday the phone technican came out and my friends line tested bad at the box. The technician fixed it, or so he said. But when my friend put his small idiot-light type tester in his phone receptacle, it indicated "reversed polarity". (I suppose that could be the fault of the apartment's installation.) He swapped two wires and now his phone works. However there is a peristent 60 HZ hum while we are talking.

[paul cottingham]

The phone shouldn't care about reverse polarity. The hum is odd, though.