# What is the formula to calculate the resistance of a cable?

Table of Contents

## What is the formula to calculate the resistance of a cable?

Engineers often ask how to calculate the resistance of a cable, there is a very simple formula that works well within an ohm or so with copper cable. 19 ÷ by 2.5mm² will give you 7.6 ohms per km. ÷ by 1000 for resistance per meter. 19 ÷ by 4mm² will give you 4.75 ohms per km.

## What is the resistance of 1000 feet of wire?

Common Wire Gauges

AWG wire size (solid) | Diameter (inches) | Resistance per 1000 ft (ohms) |
---|---|---|

16 | 0.0508 | 4.016 |

14 | 0.0640 | 2.525 |

12 | 0.0808 | 1.588 |

10 | 0.1019 | 0.999 |

## What is the resistance of 1000 feet of #6 aluminum?

Wire Resistance & Properties (AWG & Metric)

AWG | Stranding | D.C. Resistance (Ohms/1000 feet) |
---|---|---|

Aluminum | ||

10 | solid | – |

8 | solid | – |

6 | 7 | 0.808 |

## What is 250 MCM wire?

For example, one common wire size used in the NEC has a cross-section of 250,000 circular mils, written as 250 kcmil or 250 MCM, which is the first size larger than 0000 AWG used within the NEC. 1000 circular mil equals 0.5067 mm2, so for many purposes, a ratio of 2 MCM ≈ 1 mm2 can be used with negligible (1.3%) error.

## What is the resistance of a cable?

Resistance describes how strongly a given cable opposes the flow of an electric current, and conductance measures a wire’s ability to conduct it. There are also two physical quantities associated with them – electrical resistivity and electrical conductivity.

## How many ohms should a good wire have?

Typically, good wire connections have a resistance of less than 10 Ω (often only a fraction of an ohm), and isolated conductors offer a resistance of 1 MΩ or greater (typically tens of megohms, depending on humidity).

## What is the resistance of a 20.0 m long piece of 12 gauge copper?

0.104 ohms

So that’s 1.72 times 10 to the minus 8 ohm meters times 20.0 meters—length— multiplied by 4 divided by π times the diameter squared and this gives 0.104 ohms is the resistance of this piece of wire.

## What is the diameter of 350 MCM wire?

WIRE SIZE / STRANDING | Approx. Insulation Outside Diameter | |
---|---|---|

AWG / kcmil | Strands | Dia Inches |

350 | 37 | 0.800 |

400 | 37 | 0.843 |

500 | 37 | 0.925 |

## What is 300 MCM wire?

Product Details

Cable Type | THHN/THWN-2 |
---|---|

Wire Size | 300 MCM |

# of Conductors | 1 Conductor |

Conductor Material | Bare Copper |

Stranded or Solid | Stranded |

## What is the resistance of 4mm cable?

Resistance and Reactance per km of Copper and Aluminium cables

Cable Size, S (mm2) | Single – Core Cable | Two – Core/Three Core Cables |
---|---|---|

R(Ω/km) @ 80°C | X(Ω/km) @ 80°C | |

1.5 | 24.384 | 0.118 |

2.5 | 14.680 | 0.109 |

4 | 9.177 | 0.101 |

## What is the resistance per meter of 1.5 mm cable?

Table 5.5 – Resistance per metre of copper conductors at 20°C for calculation of R1 + R2 | |
---|---|

Conductor cross-sectional area (mm²) | Resistance per metre run (m ohms / m) |

1.0 | 18.1 |

1.5 | 12.10 |

2.5 | 7.41 |

## How big is a 350 MCM building wire?

Size: 350 MCM Number of Strands: 37 Cross Section Area (mm2): 177.00 PVC Insulation Thickness (Conductor): 1.520 mm / 0.060 inches Nylon Jacket Thickness: 0.200 mm / 0.008 inches Outside Diameter: 20.752 mm / 0.817 inches Weight: 1.172 lbs per ft Allowable Ampacity: 260 Amps at 60ºC / 310 Amps at 75ºC / 350 Amps at 90ºC

## How to calculate the resistance of a cable?

The formulas assume a cable configuration as shown in the figure above. Additionally, since the inductance is dependent upon its material surrounding, use Table-4 to determine an appropriate “K” factor (multiplier) for the inductance. The resistance of the conductor is provided at 20 deg.C in Table-1.

## What is the resistance of aluminum stranded conductors?

CONDUCTOR DATA SHEET ALL ALUMINUM STRANDED CONDUCTORS ( AAC ) Approx. Maximum dc Code overall Rated resistance Name Aluminium diameter Strength at 20 oC AWG or AWG or MCM MCM Peachbell 6 13.28 8 8.1 7/1.554 4.66 36.6 2.485 2.164 Rose 4 21.14 6 12.9 7/1.961 5.88 58.3 3.958 1.359 Iris 2 33.65 4 20.5 7/2.474 7.42 92.8 5.976 0.8539

## How to calculate surge impedance of a cable?

The surge impedance of the cable can be calculated with the following formula: Where: Z o = Surge Impedance of the Cable (ohm) L C = conductor inductance (mH) C = total capacitance of the cable (microfarads) . .