Cause of intermittent hum/short in phone line wiring?

Question

I am having an intermitted problem with my phone line. The line will go off-hook spontaneously (short) and when I pick it up, I hear a loud low-frequency (very possibly 60 Hz) buzz or hum. Also two of my phone extensions go dead entirely. This will continue for some period of time and then go away. It happens fairly infrequently (making it hard to call someone to come in and look at it). I have disconnected all the phone equipment and it does not go away. Testing at the demarc proves that the fault is in my wiring. Some of the wiring is inaccessible (within walls) and it's probably fairly unlikely that the accessible wiring would have a problem. What might cause this problem and how can I help diagnose it?

I've examined the demarc and sanded the wires there. I originally thought it only did it when it rained but that turns out not to be true, even when it hasn't rained in a while it will do it. It happens on all phones, by the way (excluding the dead ones), and when I disconnect each one (i.e. the short is not in a phone).

I sure wish my life was interesting enough to merit bugging my phone!

Max,

Thanks for the detailed response.

I determined the fault was in my wiring by following the instructions inside the demarc. Briefly, there is an RJ-45 jack inside the demarc that when you plug in a set, it disconnects the inside wiring automatically. You wait a minute, and if the set works fine, the problem is in your wiring.

There is nothing like the lightning fuses you describe in the customer-accessible portion of my demarc. There are some wiring blocks which could conceivably enclose them, but if the blocks are removable, I could not figure a way to remove them. I suspect though that such fuses would be installed on the telco side of the demarc.

I haven't futzed with my wiring recently.

I haven't done exactly as you said -- I removed every phone individually but I didn't remove them all and reconnect them individually. I'll try that next time it happens. Also I have two wires going into the house, I should be able to determine which one is causing the hum.

Answer 1

How did you determine the fault is in your wiring? When you were testing at the demarc, did you disconnect your inside wire and connect a telephone butt set to the underground cable (a short piece of wire with a jack and phone connected to it can work as a telephone butt set. Connect the green and red or white/blue and blue white wires to the underground outside wire)?
On your demarc connecting block there are carbon lighting protector fuses. They typically look like brass screws about the size of a dime. There are typically four. You only need two. Swap the two protectors being used (probably for the white and blue wires of the underground cable) with the two that are not being used. If your telephone line was hit with lightning, these can blow causing a ground hum.
When you were testing the phones, did you unplug all phones and plug each phone in one at a time? If the problem reoccurred when a particular phone was plugged in, did you swap that phone with another? Was there any work done recently on or around your inside wire? Laying wall to wall carpet often knicks wires. Cable staples sometimes penetrate wire causing hum.

Answer 2

Make sure that all the connections, are tight fitting. Check the wires, going into the receiver, look for poor wiring, and some insulation missing, as it goes into the receiver. Check that the connections are not starting to corrode, get a small piece of sandpaper, and go over the connections, on the cradle, and the receiver. This will make a better connection. Any little thing like that, could mean that your connection is bad..Follow the phone line, where you can, to make sure the wire is in good shape. Check to see, if the wires connecting to the connectors, inside of the phone, are tight. The outside cover should come right off, so that you can check the connections..Sometimes, when you slam the phone down, it could loosen a connection, someplace inside the phone, after doing this a few times.

Answer 3

You need to disconnect each line individually at the phone box and test the lines.

I recently had a similar problem and the short was apparently in a conduit pipe inside a wall. I did not tear out the wall to find the short, I ran another line.

When the wires are all connected, a short will affect them all.

But, the only way to find the problem is to disconnect each pair (one at a time) at the box and see if the problem occurs.

Answer 4

I have heard that some areas have Rabbit infestations. Rabbits are known to eat through telephone wiring - sometimes going behind the walls to specifically root out the telephone wires, leaving the others in tact. Do you have a rabbit? Does this rabbit have a history of chewing electrical cords? If so, then this is definitely the case.

Answer 5

It it happens with only one extension, it's in the walls, but this seems to be all extensions which seems to say a more direct problem, at the outside box or between the box and the first 'Y'.

I'd start with the box, checking it for shorts, and for water. From there you will most likely have to get under the house and check the wires.

Answer 6

Government phone bug. Be afraid, be very afraid.

Answer 7

really ? yea its frayed he probably switched the cables neg on pos and pos on neg . change that positve cable, i run from the pos post of the battery straight to the starter selenoid. good luck if its not damaged .

Answer 8

They ___Some one Has your Phone Bugged...