Page 94 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

5 Good mechanical protection.
6 Very good appearance.
Disadvantages
1 Good workmanship is required.

2 It is not used under the situations open to sun and rain.
Application
1 Used for lighting purposes in domestic, commercial or industrial buildings except in workshops where it is
liable to mechanical injury.
Lead sheathed wiring system
1 It is used for low voltage installation.
2 It is not suitable where acids and alkalies are present
3 Single, two and three core lead covered VIR cables are used
4 The cables are fixed to the wooden batten (thickness more than 10 mm) by means of nails and joint clips or
link clips
5 Clip distance for horizontal run-10.cm,for vertical run -15.cm
6 The wooden battens are fixed on the wall by means of wooden screws at a distance of minimum 60.cm and
max. 75. cm
7 When lead sheathed wiring system pass through a floor or a wall, the cable must pass through conduits
8 The bending radius of these cable should be not less than 10.cm
9 The lead sheath should always be electrically continuous and properly earthed.
Advantages
1 There is sufficient mechanical protection to the cable due to the lead sheathing on the cable
2 Protection from fire is also good

3 This system provides good protection from dampness if the ends of the cables are properly sealed
Disadvantages
1 Expensive
2 Lead sheath of the cable can be damaged due to the bad workmanship

3 Not suitable where fumes and acids are present
Application
1 It is used in low voltage installation.
2 It is used in damp places with protective covering.
3 It is not used in places where chemical corrosion may occur.
Conduit wiring

Types
Surface conduit (PVC &Metal) Done on wall surfaces
Concealed conduit (PVC)Done inside concrete plaster or wall
Types of conduit

1 Rigid steel conduit
2 Rigid non-metallic conduit
3 Flexible steel conduit
4 Non -metallic conduit

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