Calculate Conduit Size for Wires / Cables

Example: Calculate Size of Conduit (Hume Pipe) for Following Size of Cables

  • 5 No’s of 3.5 Core 50 Sq.mm XLPE Cable. Diameter of cable is 28mm
  • 3 No’s of 3.5 Core 185 Sq.mm XLPE Cable. Diameter of cable is 54mm

% Fill Up Area of Conduit

No of Cables % Fill up Area of Conduit
Up to 2 No’s 53%
2 No’s 31%
More Than 2 No’s 40%

Calculations:

  • Area of Cable =3.14 X (Diameter/2)2
  • Area of 50 Cable =3.14X (28/2)2 =615.44 Sq.mm
  • Total Area of 50 Cable=No of Cable X Area of Each Cable
  • Total Area of 50 Cable=5X615.44 =3077.2
  • Area of 185 Cable =3.14X (54/2)2 = 2289 Sq.mm
  • Total Area of 185 Cable=No of Cable X Area of Each Cable
  • Total Area of 185 Cable=3X2289=6867.18
  • Total Area of Conductor= Total Area of 50 Cable+ Total Area of 185 Cable
  • Total Area of Conductor=3077.2+6867.18
  • Total Area of Conductor=9944 Sq.mm
  • Suppose We Select 150mm Diameter Hume Pipe
  • Total area of 150 mm Diameter Hume Pipe =3.14 X (Diameter/2)2 =3.14X(150/2)2.
  • Total area of 150 mm Diameter Hume Pipe=17662 Sq.mm.
  • % Fill up Area of Conduit due to Cables as per above Table is 40%
  • Actual Fill up Area of Hume Pipe =40% X Area of Conduit =40% X 17662
  • Actual Fill up Area of Hume Pipe =7065 Sq.mm
  • Required No of Conduit = Total Area of Cables / Actual Fill up Area of Conduit
  • Required No of Conduit = 9944 / 7065
  • Required No of Conduit= 2 No’s
  • Suppose We Select 3000mm Diameter Hume Pipe
  • Total area of 300 mm Diameter Hume Pipe =3.14 X (Diameter/2)2 =3.14X(300/2)2.
  • Total area of 150 mm Diameter Hume Pipe=70650 Sq.mm.
  • Actual Fill up Area of Hume Pipe =40% X Area of Conduit =40% X 70650
  • Actual Fill up Area of Hume Pipe =28260 Sq.mm
  • Required No of Conduit = Total Area of Cables / Actual Fill up Area of Conduit
  • Required No of Conduit = 9944 / 28260
  • Required No of Conduit= 1 No’s

Results:

  • Either We Select
  • 2 No’s of 150 mm Diameter Conduit /Hume Pipe or
  • 1 No’s 300 mm Diameter Conduit /Hume Pipe
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About Jignesh.Parmar
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical) from Gujarat University. He has more than 14 years experience in Power Transmission-Power Distribution-Electrical energy theft detection-Electrical Maintenance-Electrical Projects(Planning-Designing-coordination-Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He is Freelancer Programmer of Advance Excel and design useful Excel Sheets of Electrical Engineering as per IS,NEC,IEC,IEEE codes. He is technical Author for "Electrical Mirror" and "Electrical India" Magazines. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

14 Responses to Calculate Conduit Size for Wires / Cables

  1. Md afzal alam says:

    In the formula area u have written radius/2 but it shuld be diameter/2. So please update

  2. Dear jignesh,

    I have just come to know about you via net.
    Iam working for Pacific Batteries Limited as a Export Manager ,based in Fiji Islands. We manufacture around 100,000 pcs of Automotive batteries and export to the South Pacific countries,Vanuatu, Solomon islands , Australia , New Zealand , PNG and to Saudi Arabia .
    However, we have a major issue of rapid voltage drop on new batteries.
    We need your help and support to guide us and advise why this is happening.

    The fully charged batteries 12V battery has a voltage of 12.65 Volts
    This battery is expected to maintain voltage for 5 months and should not go below 12.40 volts .
    However, we find that the voltage goes below 12.40 volts in just a month or so and we are not able to find a solution to this ongoing problem.

    We can make a deal and will contract you to assist us in this situation .

    Our Web is currently for re-designing

    Regards
    Bimal Narayan Singh
    Export Manager
    Pacific Batteries Limited
    Lot 20/ 21 Wailada Industrial Estate
    P.O.Box 3082
    Lami – Fiji Islands

    Phone : +679 3362708 / 3362255
    Mobile : +679 9990081

  3. Gajendira says:

    Dear sir,

    I need 440 kV transmission line construction details, design criteria, and maintenance manual. Or standard.
    .
    Regards,
    Gajendiran M

  4. c.sundarrajan says:

    Dear sir how to find out the steam turbine generator efficiency.20MW,11KV,1358A,0.8lag,1500RPM.Thanking you sir.

  5. zamir Ahmad says:

    knowledgeable information

  6. Sein Lin says:

    Thank you. This is useful for those who are willing to calculate conduit size.

  7. sandeep says:

    Jignesh would like buy your Electrical tools.Can I get the C.D for it

  8. minto says:

    sir, i have got resistance between one of phase cable and ground 10 giga ohms while other phases are at more than 100.Is there any problem in energizing the cable.

    cable is between Package substation .Is there any problem to energize the loop with out connecting load.

  9. Gajanan Kale says:

    Thanks for giving such valuable information .

  10. shine says:

    Sir what is the % fillup area of conduit pls rply sir

  11. vijay says:

    hi sir what is runs in a cables…for ex:1RUNS/2RUN and how we find this one..

  12. Akhilesh Dubey says:

    Is that any IS/Electrical standards for Conduit Size for Wires / Cables??
    Akhilesh Dubey

  13. mohamd salama says:

    very good useful information thanks

  14. dheer says:

    how to find the phase to phase bus bar clearance for low voltage.

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