electrical accessories

Electrical Accessories and Their Uses:
"The item used in domestic and industrial electrical wiring are called electrical accessories, e.g., switch, holder, socket, plug-top, ceiling rose, fuse cut-out etc. A switch is used to make a circuit ON and Off. A holder is used with a lamp, a ceiling rose is used a with a ceiling fan, tube light or a pendant lamp. A socket is used to provide main supply to a portable appliance, such as, table fan, table lamp, electric iron, radio, T.V. etc. A fuse cut-out is used to stop an excess flow of current in a circuit.

1. Tumbler Switch
2. Flush Switch
3. Knife Switch
4. I.C. Main Switch

(1). Tumble Switch: It is a 5 ampere  current rating switch which is used in domestic electrical wiring. It is also known as a surface switch. it can can be fitter on a wooden board or a round block. it is made of Bakelite in various shapes and designs, while  selecting a switch one should check the time taken be it in closing or opening a circuit, position of terminal, size of terminal, space for connecting wires. insulation and the function of contact points. the types of tumbler switch are as fellows.

(a) Single way Switch- it is a two terminal switch which is used to control a single circuit (i.e., a lamp, fan, tube light etc.) it may be round or rectangular in shape 

(b) two way switch- it is a four terminal switch which is used in staircase or godown wiring.

(c) Intermediate Switch- it is used alongwith a two way switch to control a lamp etc. from more then two places.

Tumble Switch

(d) Bed switch- it is a handing type single way switch is used with bed lamps.

(e) Grid Switch- it is used in machines such as an electric drilling machine.

(f) Duplex Switch- it is used in machines.

(g) Bell push Switch- it is spring type single way switch which is used with an electrical bell to make the circuit ON for a very short time.

(2) Flush Switch: These are generally 5 to 15 amperes current rating switch. the main part of the switch remains within the board and only 'ON-OFF' part remains visible. in this way these switches remains safe from dust etc. and their contact points remains clean. these types of switches take a little time in closing or opening a circuit. these may be of a single way type two way type, bed switch type or a bell push type.

(3) Knife Switch: it is a coverless switch, therefore it can be used in workshop, sub-stations and distribution stations etc. it should be fitter in such in such a way that it may remain beyond the approach of the general public and dust or water. it may be of a single throw or of a double throw type. A single-throw switch can 'ON-OFF' a single one line in one direction , and it can open the first line and close one second line in the other direction simultaneously. it has a Bakelite handle. both the above types of switch and knife switches for a single phase line and for a three line are built separately. these switches can control a circuit having 30 to 1000 amperes of current.

Single Throw Knife Switch

Double Throw Knife Switch

(4) I.C. Main Switch: An I.C. main switch has a case of cast iron and that is why it is called an iron clad main switch. porcelain fuse cut-outs are fitted inside the switch and a handle is fitted outside the switch. a square shaped Bakelite rod is attached to the handle. U-shaped clips are fitter on the square shaped Bakelite rod. when the handle is moved upwards then the U-shaped clips make the circuit ON by joining the contact point when the handle is moved downwards then the switch males the circuit OFF. line wire are usually fitter to the bottom side and the load wires to the top side of the. switch.

I.C. Main Switch

These switched are of following two types: 

1. I.C.D.P. Switch (iron Clad Double Pole main Switch)
2. I.C.T.P Switch (Iron Clad Triple Pole main Switch)

Both types of switches are made in different size to control the circuit currents from 15 to 300 amperes. An I.C.D.P. switch is used is a single phase line and an neutral line and an earthing also

Lamp Holders and Their types:

A lamp holder is used for connecting a lamp to the eclectic line. there are following two main types of lamp holders. 

(1) Bayonet Cap types.

(2) Edison Screw Type.

(1). Bayonet Cap Type- As has two L-shaped slots for holding the lamp. the base of the lamp has two project pins. when the bulb is gently pushed into the holder and turned slightly in the clock-wise direction then the pins of the lamp get entangled in the slots. the holder has two spring controlled plungers for making contact with the filament terminals of the lamp. spring controlled plungers are screwed into two brass terminals, and the supply wires are fitted on these brass terminals with small screws. the holder has a screw-cover and a clamping ring also. A bayonet cap type holder is used for lamps up to 200 watts. these are six main types of holder which are as follows. 

Bayonet Cap Holder

(a) Pandent Holder 

(b) Batten Holder

(c) Bracket Holder

(d) Two Way Holder

(e) Three Way holder

(f) Holder with Switch

Pandent, Batten and Three Way Holder are shown 

(2) Edison Screw Type- As treads inside its body. the lamp to be fitted in this holder also has treads. therefore. the lamp is screwed in the clock-wise direction for fitter it in the holder. the lamp has one fitter terminal at its cap and the other  at its treads. similarly, the holder has one connection leaf at the top and the other  at the treads. this holder is used lamps above 200 watts.

Edison Screw Type Holder

Ceiling Rose, Pin Plug, Socket and Adopter:

(1) Ceiling Rose- It is used for connection a ceiling fan,fluorescent tube, exhaust fan or pendent lamp. it is made of bakelite or porcelain. it has two or three pins for connection third pin is connection to earth line, it is designed to work at 250 volts and 5 amperes.

(2) Pin Plug- it is used for connection a portable appliance, e.g., table fan, table lamp. electric iron, radio, T.V etc.to a socket it may be two or three pin type. A two pin plug is used at 5 or 15 amperes. the third pin is the earth line pin and it is thicker than the two other pins.it is also made of bake of bakelite.

(3) Socket- it is used for taking the supply for a portable electrical appliance in conjunction with a plug-top. it this two or three hollow brass pins. there is small screw at the bottom of each pin for fighting the wire to the pin According to pin numbers there pin socket. A two pin socket is used at 5 amperes and a 3 pin socket is used at 5 or 15 amperes. the third pin is usually larger and thicker than the two other pins and it is used for earth line.

(4) Adapter- The dialectical accessory used for taking additional connections from a socket or a holder is known s adapter. the types of adapters are as follows 

(1) single adapter-it is used with a lamp holder for taking an addition. sometime it is called a lamp holder adapter.

(2) Socket Adapter- it is used with a socket. A lamp holder is built on is other end.

(3)Parallel Adapter- it is used with a lamp holder. one holder and two socket are built on its body in three different sides.

(4) Multiplug Adapter- it is used with a socket. three socket are built on its body in three different sides.