MODULE 2

PVC & Metal Conduits

Casing & Capping System
Panel Boards
Switches
Distribution Boards
Electrical Conduits
 The term "electrical conduit" refers to durable tubing or other types of enclosure used to
protect and provide a route for individual electrical wiring conductors.
 Conduit is typically required where wiring is exposed or where it might be subject to damage.
 Conduit must be installed in accordance with the National Electrical Code (NEC) and all
applicable local code rules.

PVC CONDUITS
 Polyvinyl chloride (PVC) is a combination of plastic and vinyl that is used to make PVC
pipes.
 PVC is also used to produce electrical conduit.
 While regular PVC and electrical conduit PVC are both made from the same type of plastic,
they are not the same thing, nor should they be used for the same applications.
 PVC conduit can be a good option for supporting cabling in electronic security installations
Electrical Conduits
Advantages of PVC
 Light weight, flexibility
 Resistance to combustion, corrosion and chemicals
 Ease of connection
 Simplicity of installation
 It also requires less skill
 Cutting the conduit is a straightforward process you can undertake with a set of hand shears
 Disadvantages of PVC conduit
 Physical weakness compared to metal.
 PVC can break and splinter when exposed to physical stress.
 It also needs to be supported when installed in longer runs due to sagging

 You’ll get better bending angles once you raise the temperature of the PVC to about 75 C
 Electrical Conduits
METAL CONDUITS
 Metal conduit comes in many forms and can be made from galvanized steel, stainless steel, or
aluminum.
 Other types of metals are generally not used for conduit.
 Metal conduit may sometimes be used as a grounding conductor, conduit circuit length is
limited
Rigid Metal Conduit—RMC
 Thick-walled, threaded tubing
 Generally made of coated steel, stainless steel, or aluminum.
 The conduit is connected together by screwing connectors to the main
tubes
 It can be used as a grounding conductor for short runs, but it is best
practice to use wiring that has a grounding wire.
 It is typically used outdoors to provide protection from damage and can
also provide structural support for electrical cables, panels, and other
equipment.
Electrical Conduits
Electrical Metallic Tubing—EMT
 EMT is an unthreaded, thin-wall metal tubing generally made
of coated steel, though it may be made of aluminum.
 It is a popular choice for electrical conduit in commercial
buildings, but is generally not used in residential buildings.
 Electrical Metal Tubing is less expensive and 40% lighter than
GRC.
 Another example of a rigid electrical conduit is EMT
(electrical metal tubing), which is most commonly made of
galvanized steel but can also be aluminum.
 EMT is also called "thin-wall" conduit because it is thin and
lightweight, especially compared to RMC.
 It is commonly used for exposed indoor wiring runs in
residential and light commercial construction.
Electrical Conduits
Intermediate Metal Conduit (IMC)
 Intermediate Metal Conduit (IMC) has walls that are thinner than RMC, but thicker than EMT
 Intermediate Metal Conduit is threadable, but it can also be un-threaded and used with clamp-
type fittings.
 IMC is generally made from steel and can be coated.

Flexible Metal Conduit (FMC)

 Flexible metal conduit (FMC) is typically available in diameters between 3/8" and 3", but
larger sizes can sometimes be found.
 It is made by coiling self-interlocked aluminum or steel strips, which forms a hollow tube that
wires can be pulled through.
Casing & Capping System
 The process of connecting different accessories for
distributing electrical energy from supplier to home
appliances such as lamps, fans and other domestic appliances
is known as Electrical Wiring.
 Casing Capping is one of the oldest wiring systems and has
been very popular and frequently used.
 Even in today’s world, post introduction of conduit or
sheathed wiring systems, it is still a preferred wiring system.
 PVC insulated wires are placed in the plastic casing and
covered with a cap, hence the name ‘Casing Capping’.
 Casing is a rectangular strip where the cables run through it
having grooves.
 The standard length of ‘case and cap’ is 1 meter and are
available in size of 1.5 inch in width and 0.8 inch in thickness.
 The durability of this wiring system is 20 years
approximately. It is mostly used in Home and Office spaces.
Casing & Capping System
Advantages of Casing Capping Wiring
 This wiring system is way cheaper than sheathed and conduit wiring systems.
 It is considered safe from smoke, dampness and humidity.
 Customized installation can be done in this wiring system.
 Reduced risk of electric shock can be expected.
 Repairing becomes very easy if phase and neutral wire is installed in separate
slots.
Disadvantages of Casing Capping Wiring
 There is a risk of major fire due to short circuits because of plastic in this
wiring system.
 This wiring system is not suitable in acidic conditions in industries.
 Difficulty in finding any fault caused in the wire.
Panel Boards
What is an electrical panel board?
 Panel boards are used to safely distribute electricity throughout
commercial and industrial facilities.
 A panelboard is a component of an electrical distribution system
which divides an electrical power feed into branch circuits, while
providing a protective circuit breaker or fuse for each circuit, in a
common enclosure.
 A panelboard services to protect branch circuits from overloads and
short circuits.
What is the difference between a switchboard and a panelboard?
 Switchboards and panelboards provide a similar functionality in a
power distribution system.
 Panelboards are typically flush mounted or surface mounted and are
limited to a maximum of 1,200 A incoming current (main).
Switches
 Electric switch, device for opening and closing electrical circuits under
normal load conditions, usually operated manually.
 There are many designs of switches; a common type—the toggle, or
tumbler, switch—is widely used in home lighting and other applications.
 The so-called mercury, or “silent,” switch is used extensively for
controlling home lighting circuits.
 The aggregate of switching or circuit-breaking equipment for a power
station or a transforming station, frequently located in an outdoor yard
(switchyard) beside the station, is usually regarded as switchgear.
 A switch in an electronic device is used to interrupt the flow of electricity
or electric current.
 A switch is an electronic device which is used to break or make the
electronic circuit.
Switches
Types of switches depending on the specifications
One-way (single-pole) electrical switch
 A one-way or single-pole electrical switch is the most common one in use.
 They are used to control lights, fans, or other devices from a single location. It has a simple
ON and OFF marking.
 A single-pole or one-way electrical switch generally comes with two brass-colored screw
terminals and is connected to the “hot” (current-carrying) wire, which is usually black.
 One of the brass terminals is for the incoming hot (current-carrying) wire, and the other
terminal is for the outgoing hot (current-carrying) wire to the device.
 Most of the one-way switches also include a ground terminal for connecting the circuit’s
ground wire.
 When it is turned ON, the two terminals are connected, and when it is turned OFF, the contact
between the two is broken.
Switches
Two-way (double-pole) electrical switch
 A two-way or double-pole electrical switch is generally used in industrial applications but can
also be found in some home wiring systems.
 A two-way or a double-pole electrical switch may also have the ON and OFF markings on
them.
 These switches control a device or equipment from more than one location.
 A double-pole switch has four hot brass terminals
 It also has a ground terminal, allowing you to connect it to two pairs of hot wires.
 A two-way or double-pole switch is basically two, one-way switches combined into one.
 They are able to control higher-demand appliances, like motors, and machinery.
Distribution Boards
 The Distribution Board, refers to an equipment which consists of bus
bars, and possible switches, fuse links and Automatic protective
equipment, bypass equipment, for connecting, controlling and
protecting a number of branch circuits fed from one main circuit of a
wiring installation in a building or premises for easy and safe
handling of incoming power supply.
 Used to protect the electrical distribution system in turn, connected
electrical equipment from being damaged due to various faults like
short circuit, over load, earth leakage, etc.
 An assemblage of parts including one or more switches and fuses
arranged for the distribution of electrical energy to final sub-circuits
 Main distribution board
 Branch distribution board
Distribution Boards
Main distribution board
 Provided with a circuit breaker on each circuit, or a switch with a fuse on the fuse or live
conductor and link on the neutral or earthed conductor of each circuit.
 The switches shall always be linked
Location
 The location of the main board should be such that it is easily accessible for fireman and other
personnel to quick disconnect the supply in case of emergencies
 Provision for locking arrangement
 Open type switch boards shall be placed only in dry situations
Installation on distribution boards
 The distribution fuse boards shall be located as near as possible to the centre of the load they
are intend to control
 They shall be fixed on suitable wall and shall be accessible for replacement of fuses, and shall
not be more than 2m from the floor level
 These shall be of either metal clad type or all insulated type
Distribution Boards
Branch distribution board
 Provided with a fuse or MCB or both of adequate rating/setting, on the live conductor of each
sub-circuit and the earthed neutral conductor shall be connected to a common link and be
capable of being disconnected individually for the testing purposes.
 Lights and fan may be wired on a common circuit
 Such sub-circuits shall not have more than a total of ten points of lights, fans and 5A socket
outlets
 The load of such circuits shall be restricted to 800watts