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Electrical Wiring Accessories

After studying the different electrician tools, we will study about the different electrical accessories, which are being used in domestic as well as commercial wiring. Although there are hundreds of electrical accessories available in the market but some important electrical accessories

i. Switch

A switch is used to make or break the electric circuit. Or it is used to switch “ON or OFF” the electric supply. When we switch off the electric supply, the arc is produced between the switch blades and contacts terminals. This arc may burn or damages the contacts of the switch. Formation of this arc should be avoided.Usually, this arc is avoided by means of providing a spring action movement to these switching blades to have a quick switching on or off the supply. In this way,the chances of formation of arc are drastically reduced depending upon the circuit load. The switches may be one-way switch and two-way switch. The one-way switch is used to control single circuit or lamp, where as the two-way switch isused to divert the flow of current to either of two directions. The two-way switch can also be used to control one lamp from two different places (As in case of stair case wiring). The different types of switches are available in the market, depending upon the requirement, few important are detailed below

a) Surface Switch: The switches are mounted on wooden board, fixed over the surface of the wall. These switches are also known as “Tumbler switches”.

b) Flush/Piano type switch: The switches are used where good appearance is required. The switches are fixed in flush with the wall and do not project out.These switches are also known as “Piano Type Switches”.

c) Bed switch: As the name indicates, it is used to switch “ON or OFF” the light from the place, other than switch-board or from near the bed, while going to sleep or getting up. This switch is connected through flexible wire.

d) Rotary switch: This switch is used to control different lamps from one places one by one or as selector switch, to select different voltage tapping of transformer in voltage stabilizer.

e ) Push Button switch: These switches are used to control the electric bell and indicating lamps etc. When the push button is pressed, the circuit is completed and the bell or lamp is switched on. The supply to bell or lamp is switched off as the push button is released.

f) Pull switch: These switches are operated with a single pull of the cord, for the on and off position. These are also used in bedroom and bathroom. These switches are fixed near the ceiling and hence these are also known as “Ceiling Switches”.

g) Intermediate switch: This switch has four terminals and four different connection position. The main function of this switch is to control a lamp from three or more different places, along with ordinary two-way switch. Generally this switch is used in double stair case wiring or corridor wiring. This switch is also known as four-way switch.

h) Lamp Holder: As the name indicates, a lamp holder is used to hold the lamp,and connect it electrically to supply terminals, required for lighting purposes.The lamp holders may be bayonet cap and screw type. Depending upon our requirement, these lamp holders are also manufactured in different designs.

Some important types of lamp holders are detailed below:-

ii. Lamp Holder

a) Batten Lamp Holder: These lamp holders may be of brass or bakelite, with brass plunger. The holders are fixed on either on round block or wooden board with the help of wooden screws.

b) Pendant Lamp Holder: This lamp holder is used to hang the lamp from ceiling rose, with flexible wire. Some time these holders are provided with lampshades,to divert the upward light to down ward. These may be of brass or bakelite,with brass plunger.

c) Angle Lamp Holder: The angle holder is used to focus the light at an angle and is fixed directly on wall or round block with the help of gutties and wooden screws. These may be of brass or bakelite with brass plunger.

d) Swivel Lamp Holder: These lamp holders are used for lighting of shop windows,show case etc. It consists of ball and socket joint fitted between back plate and lamp holder, for the purpose to move the light to a wide angle.

e ) Bracket Lamp Holder: These lamp holders are used to focus the light on the floor or at some angle, slightly away from the walls. Light shades can also be used for diverting all light on floor. Such lamps are provided with such fittings which make them water tight so that these can be used out side the houses or for street lighting. The bracket may be of wood, aluminium and brass. The lamp holder is simply a pendant holder made of brass or bakelite.

iii. Fluorescent Lamp (Tube) Holder

These are used to hold the fluorescent tube and pin type holders are generally used.

iv. Ceiling Rose

These are fixed on walls near the ceiling. Normally these are used to provide tapping to the pendent lamp holder, ceiling fan and fluorescent tube etc through the flexible wire.

v. Socket

The sockets have insulated base with moulded base having three terminal sleeves.The two terminal sleeves having same cross-section are used to connect phase and neural wire where as the third having greater cross-section is used to connect with earth wire. These are made for 5 amps and 15 amps load. Two-pin sockets are also available, in which only phase and neutral wires are connected. These are available in 5-amp capacity. These may be surface type or piano-types. The surface type accessories are obsolete now days.

vi. Plug

The plugs are also having moulded three pins of brass or any electrically conducting material. These are also made of 5 amp and 15-amp rating. These are used for taking power from socket.

vii. Main Switch

As the name indicates that this switch is used to switch “on or off” the main supply. In other words these switches are used to control the whole supply for a house, office and machine. In single-phase circuit I.C.D.P. main switches are used,whereas in three-phase circuits I.C.T.P. main switches are used to control the supply. The main switches are of the following type:

a) I.C.D.P. Switch: Iron Clad Double Pole main switch is used in single-phase supply circuits. These are available in 15 Amp, 30 Amp, 60 Amps and 100 amperes current rating. In these switches, either two numbers of fuse links are provided or a fuse link and a neutral link is provided. The neutral wire is directly connected with the neutral link and phase wire is connected with the fuse link.Normally 15 Amp current rating main switches are made of plastic moulding instead of iron.

b) I.C.T.P Switch: Iron Clad Triple Pole main switches are used to control the three phase supply circuit. These are available in 15 Amp, 30 Amp, 60 Amp,100 Amp, 150 Amp and 250 Amps current rating. Generally these switches are also known as 3 phase 4 wires main switches. In these switches, three fuses and a neutral link is available. The neutral wire is directly connected with the neutral link and phase wires are connected with these fuse links.

viii. Fuse

It is the most common and important type of safety device used for domestic and commercial installations. These fuses are of kit-Kat type and are also known as cut-out. These cut-outs are made of porcelain in current rating of 15 to 300 amperes. The material used as a fuse wire is tin, lead, silver, antimony, copper and aluminium etc. Copper or lead, tin alloy is mostly used in ordinary fuse wire.

ix. Miniature Circuit Breaker (M.C.B.)

A miniature circuit breaker is an electro-mechanical safety device which operate and disconnect the circuit supply, when the current drawn from the circuit increases to a pre-determined value. These are used in lieu of fuses and can be fitted in consumer’s distribution board. An MCB will normally operates at 1.25 times itsrated current value. It can be reset, by simply lifting its operational knob, where as the fuse has to replace its fuse wire. Hence the miniature circuit breaker are replacing the rewirable fuses now a days.

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