Table of Contents

- 1 How do you calculate minimum CPC?
- 2 How do you determine the size of a protective conductor?
- 3 What is CPC cable?
- 4 What is the formula for isothermal process?
- 5 How do you determine the size of an earthing conductor?
- 6 Why is the CPC smaller?
- 7 How big should a mimium cable be for a short circuit?
- 8 How to calculate the CPC of a screw?

## How do you calculate minimum CPC?

In order to find the correct CPC size using an adiabatic equation you would have to determine the fault current at the end of the 16a ctt. In order to do this you would have to select a cable, say in this case 2.5mm, and, by knowing the length of the run required, find out it’s R1 + R2 by looking up the ohms per meter.

**How is adiabatic equation calculated?**

The adiabatic equation

- A=√I2tk.
- t=k2A2I2.
- Q=cmΔT.
- Q=I2Rt.
- I2Rt=cmΔT.
- I2tρrlA=cρcAlΔT.

### How do you determine the size of a protective conductor?

The size of the protective conductor shall be half the size of the associated line conductor if the c.s.a of the line conductor is more than 35mm2 & is same material.

**What is CPC size?**

3 and the normal sizes of the CPC in each cable are… 1.5mm2 T&E cable has a 1.0mm2 CPC. 2.5mm2 T&E cable has a 1.5mm2 CPC. 4.0mm2 T&E cable has a 1.5mm2 CPC. 6.0mm2 T&E cable has a 2.5mm2 CPC.

## What is CPC cable?

The circuit protective conductor (increasingly called the ‘c.p.c.’) is a system of conductors joining together all exposed conductive parts and connecting them to the main earthing terminal. Strictly speaking, the term includes the earthing conductor as well as the equipotential bonding conductors.

**What do you mean by CPC?**

CPC means Cost Per Click, and it’s a method that websites can use to determine the average times an advertiser has clicked on the relevant ad.

### What is the formula for isothermal process?

A curve in a P-V diagram generated by the equation PV = const is called an isotherm. For an isothermal, reversible process, the work done by the gas is equal to the area under the relevant pressure -volume isotherm. It is given as WA→B=NkTlnVBVA W A → B = NkT ln V B V A .

**What is adiabatic rate?**

The adiabatic lapse rate is the rate at which the temperature of an air parcel changes in response to the compression or expansion associated with elevation change, under the assumption that the process is adiabatic, i.e., no heat exchange occurs between the given air parcel and its surroundings.

## How do you determine the size of an earthing conductor?

Let we calculate the required GI earth conductor size for 20kA Fault Current at 0.5 sec. Approximately 185Sqmm. Generally, GI is availed in the busbar structure hence Or You can take any combination of conductor size such as 50×3.5 Sqmm or 25x8Sqmm etc….Earthing conductor size calculation Formula:

Material | Material Constant (k) |
---|---|

Copper | 205 |

Aluminium | 126 |

**What are the different sizes of earthing?**

Guidance on earth conductor and protective bonding conductor cross-sectional areas is given in the guide to the wring regulations BS7671. BS 7671 lists five types of earthing system: TN-S, TN-C, TT, TN-C and IT.

### Why is the CPC smaller?

That said, the main purpose of reduced c.p.c. in T&E is cost – as copper makes up most of the material cost of the cable – doing the same in conduit would produce a much smaller percentage saving.

**What size is the earth in 10mm?**

Twin and Earth (T+E)

CSA | Overall Dimensions | Approx Measurement across |
---|---|---|

bundle of strands (‘diameter’) | ||

4mm² | 11.9mm x 6.25mm | 2.56mm |

6mm² | 13.5mm x 7mm | 3.13mm |

10mm² | 17.1mm x 10mm | 4.05mm |

## How big should a mimium cable be for a short circuit?

Use 543.1.1 or 543.1.4 for size (543.1.3 is manatory if short circuit considered in main cable size). Mimium size 2.5 mm 2 if mechanically protected and 4 mm 2 if not. Use most onerous fault current/operating time and largest line conductor csa.

**What kind of cable do I need to calculate CPC?**

The cable is PVC surface conduit with 70 degrees C thermoplastic single core non-sheathed cable. That’s all the information you need to calculate both the CPC and Line conductor sizes.

### How to calculate the CPC of a screw?

In order to find the correct CPC size using an adiabatic equation you would have to determine the fault current at the end of the 16a ctt. In order to do this you would have to select a cable, say in this case 2.5mm, and, by knowing the length of the run required, find out it’s R1 + R2 by looking up the ohms per meter.

**How to calculate CPC size with adiabatic equation?**

S (in the equation) is the CPC size required. I is the fault current (which is 230 volts / Zs), but Zs = Ze +r1 +r2! (We don’t know r2, as r2 is the length of the CPC multiplied by it’s resistance per meter).