How to Troubleshoot Electric Fence Interference With a Phone Line

If you live on a farm or in some other place and your property relies on electric fences, sometimes there may be interference from the fence with your phone lines. This can be annoying if you're hearing noises but it can also slow down dial-up internet services or any services relying on use of the phone line.


  1. 1
    Identify the problem. If you can here clicks on the line, such as click, click, click, or hums, whines and buzzing noises, then it's possible that the electric fence is creating interference. Other possible sources of interference with the phone line include fluorescent lamps, a light dimmer or electric motors. If you have other possible sources of interference, don't discount them as they'll all need to be investigated.
  2. 2
    Turn off the electric fence temporarily. Check the phone line to see if the sounds are still happening. If they're not, it's a fair bet that the fence is the cause of interference. If you can still hear interference noise, check for other appliances around the house or yard.
  3. 3
    Look for the proximity of the phone lines or cables to the electric fence. If you cannot find them, call your telecommunications provider to help you identify their location.
  4. 4
    Find out whether you have long sections of phone line running parallel with the electric fence line. Such sections are more likely to cause interference than other sections.
  5. 5
    Check the fence current using a hand-held fault finder device. The optimal amount should be about 2 amps per kilometre of energised fence line. If it's higher, then it will be prone to interfere. Try to find the source of it being higher, such as deteriorating insulators or live wires touching the ground.
    • The fence will work better if mains supply is fed to the fence in the middle of your farm or yard, well away from phone lines.
  6. 6
    Check the earthing system is in good condition and check that the energiser is away from phone lines.
  7. 7
    Get an electrician or a telecommunications installer to come in and help if you're still unsure as to what to do.


  • Noise suppression chokes (noise chokes) can reduce the level of noise interference on telephone calls due to induction from power lines and electric fences. The noise interference can be heard as a clicking, hum or buzzing sound that can cause corruption to data transmission on facsimile/modem telephone calls resulting in dropouts and slow transmissions.
  • Noise suppression chokes are installed in series with a telephone services cable pair. For best results noise suppression chokes should be installed between any unbalanced/faulty sections of telephone cable or telephone exchange equipment and the source of induction (electric fence or power line).
    • If the noise interference is due to the susceptibility of the telephone exchange equipment, then a noise suppression choke should be installed at the telephone exchange MDF. Use an internal noise suppression choke Part No NC 101
    • If the noise interference is due to an unbalanced/faulty cable pair then the noise suppression choke should be installed between the unbalanced/faulty section of cable and the induction source (electric fence or power line). Use encapsulated lightning protected noise suppression choke part No NC103.
    • If the noise interference is affecting PABX in dial circuits than a noise suppression choke can be installed at the PABX equipment end of the cable pair (e.g. PABX MDF). Use noise suppression chokes mounted on a printed circuit board for KRONE frame mounting. Part No NC104 for a two choke mounting or NC105 for a four choke mounting.
    • Noise suppression chokes installed in the correct location can overcome many of your noise interference problems.


  • Always treat electricity with respect; do not touch the fence directly and always ensure that you are properly earthed when dealing with the fence. Don't make repairs you're not certain how to do - ask professionals to assist.

Things You'll Need

  • Hand-held fault checker device
  • Knowledge about where to turn the fence on and off and where the phone lines run and mains supply

Sources and Citations

  • New Zealand Growing Today, Country Computer, p. 47, December 2005 – research source.

Article Info

Categories: Farming | Phones and Gadgets