Phone Line

Discussion in 'General Electronics Chat' started by vindicate, Aug 24, 2009.

  1. vindicate

    Thread Starter Active Member

    Jul 9, 2009
    [SIZE=+0]First let me say that I'm not trying to mooch power from the phone lines or anything like that. I just want to know how much voltage/current I can give the wires in a phone line before it would be detrimental?[/SIZE]
  2. Externet

    AAC Fanatic!

    Nov 29, 2005
    I do not know what you mean by "give the wires" and your definition of "detrimental"; but shorting the wires together as worst case (zero Ohms across them), should produce a current of about 50 mA DC, and no damages will happen by such action.

    With the wires disconnected, you should get about 50 Volts DC.

    If not getting to "detrimental" means keeping the line operational; the amount of resistance between the line wires should be such that the voltage is not under 4 Volts and the current is not less than 10mA. Such condition should occur when the resistance is around 200 Ohms.

    If "give the wires" means to apply any other external power source to the telephone wires, AC or DC; you may end paying for the replacement of several miles of wire on the telephone poles while sitting in jail.

    Last edited: Aug 24, 2009
  3. vindicate

    Thread Starter Active Member

    Jul 9, 2009
    My phone lines in my house are disconnected. I don't have phone service. If I measure the voltage from a wall socket I get 0V. So I don't know how I would be harming the phone lines anywhere else.

    By detrimental I mean the wires getting hot and melting.
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    The wires should be solid, not stranded. If you can measure the diameter, you can determine the wire gauge. From the table - - you can see what current might be safe.

    Do recall that the telco wires are run throughout the house studs, and you need to be very careful about pushing enough current to heat them.
  5. scatter

    New Member

    Aug 23, 2009
    First of all I'm retired from one of the phone companies.If you alter the line the switch in the central office will see it .The C.O. person will then send out a trouble ticket for "Foreign Voltage" on the line ,and a repair person will be sent to the house to investigate. And there will be charges if it is comming from the house.You could also blow the carbons in your protector on the side of the house which also you will have to pay for. If that happens you will loose dial tone and DSL service if you have it ,and the phone company ,as we all know, will take a week or two to get there.
  6. vindicate

    Thread Starter Active Member

    Jul 9, 2009
    I don't think you understand , I don't have phone service. I am disconnected, there for I don't have DSL or dial tone. How will they be able to see foreign voltage if I don't have my lines connected?
  7. StayatHomeElectronics

    AAC Fanatic!

    Sep 25, 2008
    24 and 26 AWG are common in the telephone industry so your house would probably not have anything larger than that. The best bet is still as beenthere has suggested, measure it and see. You will have to take the telephone jack off. Maybe you will be lucky and the sheath of the wire will be marked.
  8. Von

    Active Member

    Oct 29, 2008
    If your line is disconnected at the "bridge" or similar (disconnect nick-name) then you are correct, no detection is possible.

    Nowadays the wires in your home (beyond the bridge) are likely YOUR property. Mine are. This means you are responsible for their maintenance.

    If you choose to use them for other purposes, this is your right and your responsibility.