Possible to use the KNX Cable?

Discussion in 'General Discussion' started by yi0rgos, Jan 19, 2012.

  1. yi0rgos

    yi0rgos

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    Hi All,

    Is it possible to use the KNX Cable with C-Bus? I know that KNX cable can run with live wire in the same conduit.

    Regards,

    yi0rgos
     
    yi0rgos, Jan 19, 2012
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  2. yi0rgos

    ashleigh Moderator

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    KNX cable is shielded, C-Bus cable is not. C-Bus is Cat5, and is usually about 1/3 the price of KNX cable.

    You can probably use KNX cable OK for C-Bus, the shielding might help a little (but really only if properly terminated).

    You might want to try it before you install it, though.

    There are sites around the world that have not used Cat5 cable. Some of these work fine. Some have also had very big problems. This is why it would be a good idea to try first.
     
    ashleigh, Jan 20, 2012
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  3. yi0rgos

    Arielis

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    I am using it in a little installation. I didn`t noticed any problems with it.
     
    Arielis, Jan 24, 2012
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  4. yi0rgos

    ChrisJC

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    KNX v Pink C-Bus

    I know nothing of KNX cable, but the benefit of Pink C-Bus cable to me is the following:
    1. Immediately identifiable.
    2. Signal generated noise is cut dead when terminated (can't even use a cable locator on it once it's terminated).
    3. Relatively inexpensive.

    The problem with C-Bus cable is that it must be treated as every ELV cable must, IT MUST BE SEGREGATED from the LV side. I have seen too many installations where electricians think "it's 240V rated" and run it with the LV. As far as I am aware, it is not 240V double insulated.

    The problem with shielded cable is that the drain wire should always be terminated to the earthing system AT ONE END ONLY (main switch board end) otherwise a charge is built up on it through induction. DO NOT earth both ends or it becomes a part of the earth loop and will transmit noise which defeats it's purpose.

    My opinion only.
     
    ChrisJC, Jan 24, 2012
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  5. yi0rgos

    Conformist

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    This is true when running cable. ELV cable (including C-Bus) must be separated by a 50mm air gap or physical barrier. This becomes impossible in an electrical switchboard. Every attempt shall be made to maintain segregation

    You are right... You are not permitted in Australia (.. remember there are visitors from all parts of the world on this forum) to run ELV and LV cable together.. physical barrier or air gap rules apply.... but you are also wrong. C-Bus cable is actually rated at 3.75kV... double insulation is irrelevant. This is permitted in an electrical switchboard environment but of course, every attempt to segregate LV from ELV must be made.
     
    Last edited by a moderator: Jan 24, 2012
    Conformist, Jan 24, 2012
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  6. yi0rgos

    yi0rgos

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    The main reason of starting this post was retrofit installations...

    KNX Manuals do say is OK/show that their cable can be run withi live wires and no grounding is needed...

    So it will be nice to use KNX cable, for CBUS, and be able to run it with live wire in the same conduit.
     
    yi0rgos, Mar 31, 2012
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