Electrical Wiring Definitions

Appliance

• It is an energy consuming device or equipment.

Light electrical Appliances

• It is electrical appliances whose power rating less than 5.0 kW.

Calculation of Earth Fault Current

The magnitude of earth fault current in the line to earth fault on an earthed system is determined by 

• Impedance from source to fault
• Impedance of earth return paths

Why Crushed Rock is used at the earth surface in the substation?

• We always see crushed rock spread on the surface of soil in the substation. 
• The resistivity of gravel is approximately 2000 ohm – meter whereas the soil resistivity is only 100 ohm – meter. 
• We say that the resistivity of gravel is 20 times than that of soil. 

IE Rules 50

Rule No 50 : Supply and Use of Energy

• The controls of proper capacity to carry and break the current are placed after the commencement of supply.
• A linked switch with fuses or circuit breaker is placed for low and medium voltage consumers.

Building Sub - Station For Multistoried Building

The following points to be noted for building sub - station of Multi - storied building

• A transformer with more than 2000 litre of oil shall not be located in the basement area where proper oil drainage arrangement is not provided. 
• If the transformer is installed in the building below ground level, they

Important Earthing Rules ( As Per IE Rules : 1956 )

Earthing Rules

• The following provisions should be made for earthing for system voltage greater than 125 V and medium voltage.
• Neutral conductor of three phase, four wire system and middle conductor of two phases, three wire systems shall be earthed by two separate and

Types of MCB And Its Marking

There are three types of MCBs.

Type B MCB

• They are suitable for resistive load like oven, heater, GLS lamp etc. 
• The trip system operates between 3In to 5In in the AC system whereas its value lies in the range of 4I_n to 7I_n in the DC system ( Where In is equal to rated current of MCBs )

Measurement of Earth Resistance

There is a great importance of earthing plate resistance and its surrounding area. The earth electrode resistance is defined as the area surrounded by earthing electrodes.

Colour Code For Flexible And Non-Flexible Cable As Per NEC

The colour code for non – flexible as well as flexible cable as per NEC ( National Electrical Code - India ) is given as below.

Colour code for non – flexible cable

Single Phase AC	Phase	Red / Yellow / Blue
	Neutral	Black

Protection Area Covered By Lightning Arrestor

Introduction of Lightning

• The lighting is a natural hazard which is discharged as static electricity.
•  The important point by considering damage point of view is return stroke.  
• The current discharged by the return stroke is about 2 kA to 200 kA. 

Design of Lighting System

The design of lighting system depends upon following methods.

1. Watts per square meter method
2. Lumen or Light flux method
3. Point to point or Inverse square law method

How to Find out Number of Sub Circuits in Electrical Load?

Sub Circuits

Disadvantage of single electrical circuit

• The supply to the load circuit is given through single switch as shown in the Figure A. 

Electrification of Residential Building-Multi storied Building

Simple Residential building

• The supply for residential building is 230 V, 50 Hz, single phase from distribution transformer. 
• The maximum point should be 40. 
• There is casing capping, PVC, battern wiring or surface conduit wiring is used.

Bus bar And Bus bar Chamber

• The incoming supply to bus bar is controlled by switch fuse unit or MCB. 
• The outgoing circuit from bus bar to load point is controlled by switch fuse unit. 
• The bus bar chamber is a heart of switch fuse unit and it is main junction of incoming and outgoing line. 

Digital Energy Meter OR Static Energy Meter

The Digital Energy meter works on Digital Integration operating principle. There are no moving parts in it therefore it is also called as Static Energy Meter. The output of the meter is directly proportional to Digital pulse in it.

• Meter constant : Number of Pulses / kWh

ELCB ( Residual Circuit Breaker-RCB )

Principle of ELCB

• The working principle of ELCB is based on core balance or differential current protection. When there is no leakage or fault in the system, the current passes through phase and neutral is same.

Wiring And Schematic Diagram of Corridor Lighting

Corridor Lighting

The corridor lighting is proper sequence of lighting point for control illumination at forward steps. The corridor lighting is used in the passage.

Main components of corridor lighting

Lamps, holder, two-way switches, wire, connector, cutter

Wiring Diagram of Twin Tube Light

Twin Tube light

The wiring diagram of twin tube light is shown in the Figure. The Twin tube light is generally used in the textile industry / diamond factory where high level of illumination required.

Three Lamps are Controlled By Six Switches

Three Lamps controlled by Six Switches 

Here, the wiring diagram of three lamps are controlled by six switches are given. Each lamp is controlled by two switches. It is similar to stair case wiring with multiple circuit connected in parallel.

Lamp controlled by Remote Station

Lamp controlled by three switches

Here, we explain lamp control by remote location. Here the diagram of one single lamp controlled by three different switches at different location is given. Lamp controlled is done by any of the three switches.