An electric gate company installed a gate at a residence. The gate had a key/voice pad at the enterence of the residence for communication. When they were finished the owner had static on his phone lines. I saw that the install used non-direct burial phone lines in the ground and they ran it right next to a 120 Volt feed. Although the 120 is in pvc conduit, could it still cause interference? What are the rules/codes for installing telephone lines near electricity?
Study Guides for VDV / Structured Cabling Installers
2" is minimum,(800.52(A)2) however more is wise, especially parralel.
But sure it is "static", and not "hum"?
Static can be many reasons. Loose / dirty connection, bad equipment, a whole range of things.
Hum could be induced in the way you described. Especially in PVC or cable. Metallic conduit would afford some shielding effect. Or, the use of shielded phone cable. Both would reduce it to some degree.
Isolate the noise by removing elements of the phone and gate wiring, or shutting off the gate to see if it goes away. If there is an intercom to the gate via phone that could be an issue too.
Wish you luck...
Mark Heller "Well - I oughta....." -Jackie Gleason
Also remember that a long run of cheap unsheilded phone cable is much more liable to pick up interference from whole variety of sources not just AC cables. It should ideally be properly sheilded if the cable's running a considerable distance to the gate.
Re: Telephone static#159797 01/29/0512:36 AM01/29/0512:36 AM
Many thanks for everyone's responses. The owner said the problem was static with a hum. I'm not sure if he is right. I suggested for him to assume the line from the house is okay and have the gate company just splice a new wire from the feed from the house to the control pad at the gate just to see if the problem is resolved. Sure enough, that fixed it. The little jumper is only 15 feet long, so somewhere between those points is the problem. Still not sure what it was.