Thread: Does a telephone line have an electrical current?

Originally Posted by Specialized29er

...and am wondering if the telephone line have an electrical current running through it.

I think I read once where it doesn't but I'd like to make absolute sure first...

Yes the old copper lines have a current. I believe it's 3 volts so I don't think you need to worry about receiving a fatal shock.

If your line is out of use chances are it's disconnected anyway.

None-the-less, it's probably illegal to cut it - so do it while no one is looking .

Cheers, Vann.

Yes a very low current, an old boss of mine used to stick the wires on his tongue to check if they were live if we accidentally ripped up cable whilst digging with the backhoe. So not much chance of getting a shock.

Cheers Andrew

Originally Posted by Vann

Yes the old copper lines have a current. I believe it's 3 volts so I don't think you need to worry about receiving a fatal shock.

Sticky speaking they have a voltage.

The off hook V is between 3 and about 9V, on hook V is around 50V, ring V can be up around 120V.

Current only flows when something is connected, like your tongue or a speaker, but it's all low current, <100mA.

I thought it was 48 volts. Used to be common communications equipment battery volts.
Low current so as others have said, cut it when no one is looking.

Not sure if same applies is switched over to NBN service.

Contact "Dial before you dig."

IF there is no working service connected then there will be no voltage on the line. The service (cable) from house to "network boundary" (typically the pit outside the property) is connected to the exchange through a series of "joints," "pillars" and "cabinets." It is not often that a service is directly connected to the "mainframe (MDF)." For the copper pair to carry a current it must be "jumpered" at the MDF and at any enroute "pillars" and "cabinets." It will/should be "open circuit" both ends.

However strange things happen in rural areas like DIY (illegal) modifications to the copper network including "working service" "disconnects" which are not properly isolated.

With NBN now controlling most of the network its best to contact them or "Dial before you dig" even though it is an "aerial service." The Telecommunications Act regulates who can operate, install, modify etc a "service" with regulations and standards of competence for "telco workers."

Its about 48volts. Don't play with it because its illegal and you can damage downstream services.

As said above if you disconnect it and cause damage or interference down the the line you will be liable for any associated costs, it will likely now be the property of Telstra or of the NBN, contact hem and they will most likely disconnect for no cost.

Originally Posted by China

As said above if you disconnect it and cause damage or interference down the the line you will be liable for any associated costs, it will likely now be the property of Telstra or of the NBN, contact hem and they will most likely disconnect for no cost.

"Ownership" of cabling within the boundaries of a property depends upon the location of the "network boundary". However "ownership" does not remove the obligation to maintain "cabling standards" or to have "work" performed by an appropriately qualified person who holds an ACMA Cabling Registration.

Communications Alliance - 3.14 Telecommunications Network Boundary (commsalliance.com.au)

Work as a registered cabler | ACMA

We have a private pole which we paid for and everything between the house and that pole is on us. We replaced the original underground cable with an aerial cable and our internet speed went from 18 to 52 instantly.

Originally Posted by Chris Parks

We have a private pole which we paid for and everything between the house and that pole is on us. We replaced the original underground cable with an aerial cable and our internet speed went from 18 to 52 instantly.

I think you will find that regardless who paid for it and who continues to pay for it’s upkeep you still can’t tamper with the wiring unless you have the appropriate Comms accreditation in the same manor as with gas services.

Having said that I would not have an issue removing the old service but my recollection of the event if questioned would be a tree took it out during a storm

Originally Posted by Pearo

Its about 48volts. Don't play with it because its illegal and you can damage downstream services.

The 48v or similar is very low current & designed to drop to a very low voltage when phone is off hook I.e phone puts a low resistance across the line. That is how the telephone exchange detects you lift up the hand piece off the phone.
The old rotary dial phones actually shorted the line (from memory) for every pulse.

anyway, shorting the 48v will not break the exchange.

Originally Posted by Pete57

anyway, shorting the 48v will not break the exchange.

Beside the point, its illegal to do any work on the line unless you are licenced. IF you have to ask questions about it, then you should not be touching it.

Originally Posted by Beardy

I think you will find that regardless who paid for it and who continues to pay for it’s upkeep you still can’t tamper with the wiring unless you have the appropriate Comms accreditation in the same manor as with gas services.

Having said that I would not have an issue removing the old service but my recollection of the event if questioned would be a tree took it out during a storm

That's not what we were told but not all advice is always correct especially in the confusion of the change over to the NBN.

Originally Posted by Chris Parks

That's not what we were told but not all advice is always correct especially in the confusion of the change over to the NBN.

They didn’t say an unqualified person could tamper with it did they? Yes it is yours as is the power, water, sewer and gas supply into your property but it still technically requires a professional to interfere with it