Page 119 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Bell-push or push-button switch: This is a two-terminal device having a spring-loaded button. When pushed it
`makes’ the circuit temporarily and attains `break’ position when released.

Iron - Clad Double pole (ICDP) main switch : This switch is also referred to as DPIC switch and is mainly used
for single phase domestic installations, to control the main supply. It controls phase and neutral of the supply
simultaneously (Fig 4).
The current rating of the switch varies from 16 amps to 32 amperes.
Iron - Clad Triple pole (ICTP) main switch: This is also referred to as TPIC switch and is used in large domestic
installation and also in 3-phase power circuits, the switch consists of 3 fuse carriers, one for each phase. Neutral
connection is also possible as some switches are provided with a neutral link inside the casing (Fig 5).

Fig 4 Fig 5

The current rating of the switch varies from 16 to 400 amps.
Holding accessories

Lamp-holders : A lamp-holder is used to hold a lamp. Earlier, brass holders were most commonly used but
nowadays these have been replaced by bakelite holders. These may contain solid or hollow spring contact
terminals. Four types of lamp-holders are mainly available.
– Bayonet cap lamp-holders
– Screw type holders
– Edison screw type lamp-holders

– Goliath Edison screw type lamp-holders
Bayonet cap (BC) lamp-holders: In this type,the bulb is fitted into the slot, and is held in position by means of
two pins in the lamp cap. It has solid or hollow spring contact terminals, and the supply mains through the switch
are connected to these contacts. In BC types there are two grooves on the circular construction of all types of
holders.
Pendent lamp-holders: This holder (Fig 6) is used in places where the lamps are required in a hanging position.
These holders are made of either brass or bakelite. An exploded view of this holder shows the parts of the holder.
These holders are used along with ceiling roses for suspending the lamps from the ceiling.

Batten lamp-holders: The straight batten holder (Fig 7a) is used on a flat surface on the round block, wooden
board etc. These holders are made of either brass or bakelite.
Angle holders: The angle bottom holder, (Fig 7b) is to hold the lamp in a particular angle. These are made of
either brass or bakelite. These are used for advertising boards, window display, kitchens etc.

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CITS : Power - Electrician & Wireman - Lesson 20-25 CITS : Power - Electrician & Wireman - Lesson 20-25