Telephone Cable in Electric Outlet
This house in Tennessee (USA) was built in 1998 by a truck driver who also doubles as an independent contractor building spec homes. When, this winter, we had static noise on the telephones, I looked into the telephone wiring before calling the local telephone company (AT&T). Because the telephone wiring is so strange, I have not yet called the telephone company.
There are two jacketed solid wire telephone cables coming from the telephone service box mounted on the outside of the house directly opposite the main circuit breaker box inside the garage. Those two telephone cables sneak through the brick wall by entering under the edge of the external outlet cover. I am assuming that the cables proceed through the metal outlet box and then follow the same path as the AC power to the attic where I again can see them. Each cable serves two telephone outlets within the house. All of the telephones have the line static — a kind of distorted hum.
One option to fix this would be to drill a hole through the brick wall and also through the back of the circuit breaker box and then feed the wire out the side of the box to again travel up the interior of the wall to the attic. One advantage of this approach, if even legal according to code, is that I could then mount a telephone lightening surge arrester within the unoccupied space at the bottom of the circuit breaker box and have a solid ground available.
So, my question is, “Is it even according to code to run the telephone cable through either an outlet box or through the circuit breaker box?” Would you recommend against it just from experience?
Replies
It may be that the wires are routed outside the box for the outlet, in which case the arrangement might still be a technical code violation, but not nearly as serious.
Also, remember that coming from the telephone service box there is generally an insulated ground wire that runs to the house electrical ground. Often these are routed in strange ways. I'm not sure it's technically a violation for this ground wire to be run through electrical conduits and boxes.
However, it is most certainly a code violation for ordinary phone (or other low-voltage) lines to occupy the same box or conduit (without some sort of a divider or partition) as regular electrical wiring. (When, say, Romex is run through a conduit purely for mechanical protection and the conduit is open at both ends there MAY be an exception, but that would still be very poor practice).
(And, based on the above, it would not be legal to run the phone line through the circuit breaker box, even if it immediately exits.)
And, over and above code issues, it's "poor practice" to route any audio or data cable parallel to electrical wiring unless several inches of separation is maintained. Additionally, such cables should be kept a foot or so away from any fluorescent ballasts, doorbell transformers, etc, that would tend to produce a strong magnetic field.
The sort of noise you describe can be due to a number of issues. The lightning arrester in the entrance box could be defective, or the ground wire running from it could be disconnected, or one side of the phone line could be touching ground somewhere. There can also be problems out on the pole and beyond.
One test that helps to separate these issues is to disconnect the house phone lines at the entrance box and connect a phone directly at that point to see if the noise is still present. Often there is a plug and socket arrangement in the box that makes this test quite simple.
Not Surprised
Thank you for your responses. I am not surprised that it is not good practice to run the telephone lines close to the power lines. Nor did I expect that it would be permitted to run them through the circuit breaker box.
I will check again using a telephone at the service entrance box. The connector in the service box was badly mangled and potted in RTV but I have corrected that.
Simple check
Take a phone outside and plug it into the jack in the phone company box. If the noise goes away, the problem is in the house wiring. If it persist the problem is in the wiring coming into the box.
There are two jacks in the outside box. One will have your house line pluged into it and the other will be open. Unplug your house lineand plug the phone into that jack first. Listen for the noise and repeat the procedure using the open plug.
You may need a tamper proof allen wrench or tamper proof torx bit to get into the box.
I learned from an inspector on my house that low voltage ... phone/cable TV wire cannot be in the same box w/ line voltage wire. I had to buy the special double box to keep them separate when they were beside each other. Also when you install the low voltage, I think it is recommended you maintain a distance to parallel running line voltage wire (e.g. 12").
DaveRicheson and ClewLess both touched on key points. The low voltage wiring should not be run parallel to electric. There is the chance for inductance noise from the electric wires. Ideally they would be seperated stud wall bays. If not, there should be 12" of seperation. That said, I've seen low voltage lines run right with electric and there is no problem with noise. If the noise on the line has always been there, that could be the problem.
However, if the noise is intermittent, I would be thinking the noise is from some other source. For example, there are likely many splice points along the cable that comes to your home from the local exchange office. If any of these points allow the cable to get wet (as in durring a rain or snow storm), then you could get noise on the line until the water leaves.
So before you look into re-routing the phone cable, check the phone service box. And should you decide the noise is a result of the phone cables in your home being run parallel to electric, do not use the electric panel as a shortcut into the home. You would do better to cleat the wire from the telephone service box up the outside of the home into the soffit for attic access.
Like they said....l
Go to the outside connection box, disconnect the interior wiring and plug in a phone. Does the noise go away? If so, the 'hum' you describe is almost certainly 60hz interference from the AC wires. For a parrallel run of many feet, those phone cables ought to be separated by at least a foot from the AC wires.
Good luck.