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2 parallel tel.

  1. Aug 7, 2007 #1

    I know that with option A I have an always-open-line and no problems in communication...

    What I would like to know is, if option B will work when the ground is the building ground?


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  2. jcsd
  3. Aug 7, 2007 #2


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    Staff: Mentor

    Not sure I understand your question. What kind of phones, and what is the 24V? In the US, the POTS (plain old telephone sets) use -48V for power. And if you are asking if you can use a building ground instead of the 2nd conductor in the twisted pair of phone line, the answer in general would be "not if you want a clear signal". Also, building ground is susceptible to electrical transients (like surges caused by nearby lightning strikes), so the chance of damaging the phones would increase if wired that way.
  4. Aug 8, 2007 #3
    As for damaging the phones - they wouldn be connected for a long time and I dont really care about them. :smile:

    A for noise - as long the line will work and I'll be able to understand what the person in the other end says - I'm ok with it.

    The phones are just plain phones, and 24v is enough to get the line open with no noises.
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