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Multiple pilot cables in one duct

vici
Hi everyone,


I wondered if there are any issues in installing more than one pilot cable in a duct and I would like to seek advice on standards and good practice to follow. Pilot cables in questions are of copper type, for 11kV circuits.

I'd be tempted to think about criticalities in cable pulling, but I wondered if there are additional considerations to add.


Thank you

  • 0
    Probably nothing regs wise, but are they all going to the same place and is there any risk of needing to re-pull one while others are in use. I presume the voltages and currents on the pilots are modest, and normal thermal grouping problems are not dominant concern.


    "Pilot" can mean different things - are you looking at twisted pairs and high speed data, or just to complete a230V or 24V loop to energise a contactor sort of things? There may be EMC considerations if there are high speed data signals to be co-located with things that go thump.

  • Former Community Member
    0 Former Community Member
    It's not that unusual to see the protection scheme pilot wires installed in a common duct (usually with a small separation (say 300mm) from the MV cable group. After all, we don't really have any trouble with running multiple pilot cores within the same cable sheath/screen.


    Provided the cabling is adequately robust, and is designed for protection schemes (ie typical 2kV voltage withstand and enhanced insulation at the HV termination cubicles, the I wouldn't have any issues about running a group of pilots together for say line diff protection, or fail to trip signalling. The pilots are generally monitored as part of the trip supervision scheme anyway.


    Obviously, all the practical arrangements for drawing several cables into a duct will need to be followed. The last one I specified had a "square" duct with multiple sub ducts present so I could easily arrange installation of a multicore pair and triple cable in some of the sub ducts as well as optic fibre for other elements of the protection scheme


    Regards


    OMS
  • 0
    Depending on the situation, you could fall foul of requirements for Duty / Standby circuits on separate routes or even Main protection / Standby protection circuits.


    A few clients want this sort of thing but I don't know of any general regulations requiring it.
  • Former Community Member
    0 Former Community Member

    Harry Macdonald:

    Depending on the situation, you could fall foul of requirements for Duty / Standby circuits on separate routes or even Main protection / Standby protection circuits.


    A few clients want this sort of thing but I don't know of any general regulations requiring it.




     

    Sure - but if you are segregating the power for resilience, then I'd expect the pilot wires to have the same segregation/duplication - I wouldn't usually expect (or wish to see) the relevant pilot wire separated significantly from the corresponding power cabling


    Regards


    OMS

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