## Calculation of Crippling (Ultimate Transverse) Load on Electrical Pole

July 19, 2020 4 Comments

**Calculation of Crippling (Ultimate Transverse) Load on Electrical Pole**

- Wind Speed = 89 Mile/Hr.
- Height of Pole=10 Meter
- Type of Pole =RCC
- Height of Pole in Ground=1.5 Meter.
- Pole Section on Bottom of Pole (Length x Width)=400mm x 150mm
- Pole Section on Top of Pole (Length x Width)=127mm x 150mm
- Conductor Mounting from top of Pole(g)=0.5 Meter.
- Distance between Two Pole(s) =20 Meter.
- No of Conductor on Pole(n)=3No’s
- Size of Conductor(r)= 30mm

**Calculations:**

- Wind Pressure = 00256 x 2x Wind Speed
- Wind Pressure = 00256 x 2x 90 = 20.506 Pound /Sq.Foot
- Wind Pressure(Wp) =4.882×20.506 = 100 Kgf/M2
- Wind Load on Conductor/Span(ws)=2/3 x Wp x s x r x n
- Wind Load on Conductor/Span(ws)=2/3 x 100 x 20 x 30 x 3 =
**120 Kg———–(I)** - Height of Pole Above Ground (h)= 10-1.5 =8.5 Meter
- Total Bending Movement at Ground Level due to Wind Load on All Conductor=ws x h
- Total Bending Movement at Ground Level due to Wind Load on All Conductor(b)=120 x 8.5= 960 Kg.Mt
- Equivalent Safe Working Load at said Meter from TOP of The Pole corresponding to Wind Load on All Conductors =b / (h- g) = 960 / 8.5-0.5 =120 Kg
- Wind Load on Pole Surface above Ground Level (p1)=Wp x h /((l1+w1)/(2×1000))
- Wind Load on Pole Surface above Ground Level (p1)=100×8.5/(400+150/2×1000) =233.75 Kg
- Centre of Gravity of Tapering rectangular section of Pole(p2)= (h/3)x((l2+(l1*2))/(l1+l2))
- Centre of Gravity of Tapering rectangular section of Pole(p2)= (5/3)x((127+(400×2)) /(127+400))=4.98Mt
- Bending Movement at Ground Level due to Wind Load on Pole(p) =p1 x p2
- Bending Movement at Ground Level due to Wind Load on Pole(p) =233.75×4.98=1164.98 Kg.Mt
- Equivalent Safe Working Load at said meter from Top of The Pole corresponding to Wind Load on Pole(wt) = p /(h-g) =1164.98 / (8.5-0.5) =
**62 Kg——————————(II)** - Total Transverse Load at said meter from Top of The Pole (Due to wind Load on Conductors + Wind Load on Pole Surface) (T)=Ws + Wt = 120+145.62 =256.62 Kg

Type of Pole |
Safety Factor |

Wooden Pole | 3.5 |

RCC Pole | 2.5 |

PCC Pole | 2.5 |

Steel Tubular Pole | 2 |

Rail/RSJ Pole | 2 |

Struts (Steel Pole) | 2.5 |

Struts (RCC/PCC) | 3 |

PCC Pole for 33 KV | 2 |

- From Above Table Safety Factor=2.5
- Total Transverse Load (Crippling Load) of Pole = T x Safety Factor
- Total Transverse Load (Crippling Load) of Pole = 256 x 2.5 =664 Kg.
**Total Transverse Load (Crippling Load) of Pole=664 Kg**

Max. Length of Pole (Meter) |
Min. Ultimate Transverse Load from 0.6meter from Top (Kg) |

17 | 3000 |

17 | 2300 |

17 | 2000 |

17 | 1400 |

16 | 1100 |

15 | 1050 |

14 | 1050 |

13 | 1000 |

12 | 800 |

11 | 600 |

10 | 500 |

9 | 300 |

8 | 200 |

7 | 200 |

6 | 200 |

5 | 150 |

4 | 150 |

3 | 150 |

- From Above Table Min. Ultimate
**Transverse Load for 10 Meter Pole = 500 Kg and as per our calculation it is 664 Kg hence Selection of Pole if O.K**

**Results:**

**Calculated Transverse Load (Crippling Load) of Pole = 664 Kg**

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