Calculation of Cable Tray Size

Calculate Size of Cable Tray for Following Cable Schedule. Cable Tray should be perforated and 20% spare Capacity. Distance between each Cable is 10mm. Cable are laying in Single Layer in Cable Tray.
(1) 2 No’s of 3.5Cx300 Sq.mm XLPE Cable having 59.7mm Outer Diameter and 5.9 Kg/Meter weight
(2) 2 No’s of 3.5Cx400 Sq.mm XLPE Cable having 68.6mm Outer Diameter and 6.1 Kg/Meter weight
(3) 3 No’s of 3.5Cx25 Sq.mm XLPE Cable having 25mm Outer Diameter and 0.5 Kg/Meter weight

Calculation:

Total Outer Diameter of all Cable Passing in to Cable Tray:

  • Diameter of 300Sq.mm Cable =No of Cable X Outer Diameter of Each Cable
  • Diameter of 300Sq.mm Cable =2X59.7 = 119.4 mm
  • Diameter of 400Sq.mm Cable =No of Cable X Outer Diameter of Each Cable
  • Diameter of 400Sq.mm Cable =2X68.6= 137.2 mm
  • Diameter of 25Sq.mm Cable =No of Cable X Outer Diameter of Each Cable
  • Diameter of 25Sq.mm Cable =3X28= 84 mm
  • Total Diameter of All Cables laying in Tray = (119.4+137.2+54)mm
  • Total Diameter of All Cables laying in Tray = 340.6mm

Total Weight of Cables Passing in to Cable Tray:

  • Weight of 300Sq.mm Cable =No of Cable X Weight of Each Cable
  • Weight of 300Sq.mm Cable =2X5.9= 11.8 Kg/Meter
  • Weight of 400Sq.mm Cable = No of Cable X Weight of Each Cable
  • Weight of 400Sq.mm Cable =2X6.1= 12.2 Kg/Meter
  • Weight of 25Sq.mm Cable = No of Cable X Weight of Each Cable
  • Weight of 25Sq.mm Cable =3X0.5= 1.5 Kg/Meter
  • Total Weight of All Cables laying in Tray = (11.8+12.2+1.5) Kg/Meter
  • Total Weight of All Cables laying in Tray =25.5 Kg/Meter

Total Width of all Cables:

  • Total Width of all Cables = (Total No of Cable X Distance between Each Cable) + Total Cable Outer Diameter
  • Total Width of all Cables = (7 X 10) + 340.6
  • Total Width of all Cables = 410.6 mm
  • Taking 20% Spare Capacity of Cable Tray
  • Final Width of all Cables = 1.2%X4106.6
  • Calculated Width of All Cables = 493 mm

Total Area of Cable:

  • Total Area of Cable = Final width of Cables X Maximum Height Cable
  • Total Area of Cable = 493 X 69.6 =28167 Sq.mm
  • Taking 20% Spare Capacity of Cable Tray
  • Final Area of all Cables = 1.2%X28167
  • Calculated Area of all Cable =33801 Sq.mm

CASE-(I):

  • Considering Single Run of Cable Tray having Size of 300X100mm, 120Kg/Meter Weight Capacity
  • Area of Cable Tray =Width of Cable Tray X Height of Cable Tray
  • Area of Cable Tray =300X100 = 30000 Sq.mm
  • Checking Width of Cable Tray
  • Calculated Width of Cable Tray as per Calculation=No of Layer of Cable X No of Cable Tray Run X Width of Cables
  • Width of Cable Tray as per Calculation=1X1X493 =493 mm
  • Checking Depth of Cable Tray
  • Actual depth of Cable Tray = No of Layer of Cable X Maximum Diameter of Cable
  • Actual depth of Cable Tray=1X68.6 =68.6mm
  • Checking Weight of Cable Tray
  • Actual Weight of Cables=25.5 Kg/Meter

Results:

  • Calculated Cable Tray width (493mm)> Actual Cable Tray width ( 300mm) = Faulty Selection
  • Calculated depth of Cable Tray (68.6mm)< Actual Depth of Cable Tray (100mm) = O.K
  • Calculated Weight of all Cables (25.5Kg/Mt) < Actual Weight of Cable Tray (125.5 Kg/Mt) =O.K
  • Required to select higher size Cable Tray due to small Cable Tray width.

CASE-(II):

  • Considering Single Run of Cable Tray having Size of 600X100mm, 120Kg/Meter Weight Capacity
  • Area of Cable Tray =Width of Cable Tray X Height of Cable Tray
  • Area of Cable Tray =600X100 = 60000 Sq.mm
  • Checking Width of Cable Tray
  • Width of Cable Tray as per Calculation=No of Layer of Cable X No of Cable Tray Run X Width of Cables
  • Width of Cable Tray as per Calculation=1X1X493 =493 mm
  • Checking Depth of Cable Tray
  • Actual depth of Cable Tray = No of Layer of Cable X Maximum Diameter of Cable
  • Actual depth of Cable Tray=1X68.6 =68.6mm
  • Checking Weight of Cable Tray
  • Actual Weight of Cables=25.5 Kg/Meter

Results:

  • Calculated Cable Tray width (493mm)< Actual Cable Tray width ( 600mm) = O.K
  • Calculated depth of Cable Tray (68.6mm)< Actual Depth of Cable Tray (100mm) = O.K
  • Calculated Weight of all Cables (25.5Kg/Mt) < Actual Weight of Cable Tray (125.5 Kg/Mt) =O.K
  • Remaining Cable Tray width Area =100%-(Calculated Cable tray width/ Actual Cable Tray Width)
  • Remaining Cable Tray width Area =100%-(493/600)% =17.9%
  • Remaining Cable Tray Area =100%-(Calculated Cable tray Area/ Actual Cable Tray Area)
  • Remaining Cable Tray Area =100%-(33801/60000) =43.7%
  • Selection of 600X100 Cable Tray is O.K

Conclusion

  • Size of Cable Tray= 600X100mm
  • Type of Cable Tray=Perforated
  • No of Cable Tray Run= 1No
  • No of layer of Cables in Cable Tray=1 Layer
  • Remaining Cable Tray width Area =17.9%
  • Remaining Cable Tray Area =43.7%
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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.

13 Responses to Calculation of Cable Tray Size

  1. kamarana2006 says:

    many thanks for your mail cable tray calculation it’s very useful, hope more cooperation in electrical design

    regards  Kamaran Aziz Ali

  2. Hello Jignesh JI, I got your reference form one of your blog which describes safety measure for transformers. I am no expert and looking for buying my new home but there is a pad locked transformer next to property almost sharing the wall ( may be 2 feet distance). Looking at articles i am confused whether its safe to live next to transformer with 3 year old daughter. I would really thankful if you can share your formal advise? Many Thanks in advance. Mayank Tripathi

  3. Rajesh Tayade says:

    Very perfect information given regarding cable tray. Thanks

  4. Thenks to discribe the knolged of cable tray

  5. vinoth says:

    Kindly inform me how to calculate cable tray and calculacion of cable size

  6. LIN says:

    Sir,
    May I know how to calculate cable tray size with double layer cable arrangement.

  7. thiyagarajan says:

    dear sir ,
    nice information you are provide regarding all design basis .here i have doubt in cable tray size .. actually what is mean by single layer and double layer to be consider for cable tray size.

    Thanks in Advance ,

    P.M.Thiyagarajan.

  8. srinu govinda says:

    thanks a lot for your amazing contribution

  9. ali says:

    Dear sir how you got the height of the cable, From which catalog. Most of the catalog want give the information on height of the cables.

  10. M.Deebanchakravarthi says:

    Dear sir very use full information…….by Deepan from Coimbatore

  11. Abhijit says:

    Dear sir,
    I think there is a little mistake in calculation at ‘total area of cable’. Could you please correct the calculation. I am facing problem while practicing.
    Thank you.

  12. gideon says:

    thank you

  13. khalido says:

    thats very good

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