Install electrical metallic / nonmetallic (PVC conduit)

WEB SCRIPT ELECTRICAL INSTALLATION AND MAINTENANCE NC II
Sector
Qualification: ELECTRONICS AND ELECTRICAL
Unit of
Competency: ELECTRICAL INSTALLATION AND MAINTENANCE NC II
Developer/s: PERFORM ROUGHING-IN ACTIVITIES,WIRING AND CABLING WORKS FOR
UNIT I SINGLE-PHASE DISTRIBUTION,POWER,LIGHTING AND AUXILIARY
SYSTEMS
OBJECTIVES Michael P. De Sena/ Orlando P. Saulon
Install electrical metallic /nonmetallic (PVC conduit)

At the end of this unit, you should be able to:

● Identify the different types of conduits
● Identify the different types of bends of conduits
● Identify the different types of bends defect of conduits

INTRODUCTION Electric
al conduit provides very good protection to enclosed conductors from impact,
moisture, and chemical vapors. Varying numbers, sizes, and types of conductors
can be pulled into a conduit, which simplifies design and construction compared
to multiple runs of cables or the expense of customized composite cable. Wiring
systems in buildings may be subject to frequent alterations. Frequent wiring
changes are made simpler and safer through the use of electrical conduit, as
existing conductors can be withdrawn and new conductors installed, with little
disruption along the path of the conduit.

A conduit system can be made waterproof or submersible. Metal conduit can
be used to shield sensitive circuits from electromagnetic interference, and also
can prevent emission of such interference from enclosed power cables. Non-
metallic conduits resist corrosion and are light-weight, reducing installation labor
cost.

PVC or polyvinyl chloride rigid conduit is one of the most commonly used
conduits in electrical wiring installation today. Its preparation for installation is
much easier than the metallic rigid conduit. In preparing a non-metallic rigid
conduit for installation

Activity PRE-TEST
LESSON 1
Installing electrical metallic /nonmetallic (PVC conduit)
TOPIC 1 Electrical Metallic /Non-metallic (PVC conduit)

Installation of Electrical Metallic /Non-metallic (PVC conduit)

● In conduit wiring, steel tubes known as conduits are installed on the
surface of walls by means of pipe hooks (surface conduit wiring) or buried
in walls under plaster.

● Conduit should be electrically continuous and connected to earth at some
suitable points in case of steel conduit.

● Conduit wiring is a professional way of wiring a building mostly PVC
conduits are used in domestic wiring.

TOPIC 2 Types of Conduits

● EMT Conduit Pipe
● Rigid Nonmetallic Conduit
● Intermediate Metal Conduit (IMC)
● Rigid Steel Conduit (RSC Pipe)
● Flexible Metal Conduit (FMC or Greenfield)

Type Description

● EMT ● Electrical Metallic Tubing
Conduit
Pipe (EMT), also commonly

called thin-wall, is a listed

steel raceway of circular

cross section which is

unthreaded, and

nominally 10 feet long, 20

feet lengths are also

available

● PVC can be used indoor

● Rigid or outdoors and
Nonmetallic
Conduit underground beneath

Concrete or fill.

● Easy to bend.

● Best for burying

underground as it will not

corrode with water

● Intermediat ● Can be used indoor or
e Metal outdoors and underground
Conduit beneath
(IMC)
● Concrete or fill. It can be
used in high voltage
application (over 600VAC)

● Rigid Steel ● Also known as Heavy-
Conduit walled conduit
(RSC Pipe)
● Comes in the same sizes
● Flexible as EMT but has thicker
Metal walls.
Conduit
(FMC or ● Has threaded ends for
Greenfiel connections.
d)
● Use for carrying wire
indoors or outdoors, in dry
and wet locations,
exposed or concealed, in
all kinds of atmospheric
conditions, and in
hazardous locations.

● Rounded channel-iron
shape provides strength
and make fitting easy

● over the roller-bearing
surfaces. Spring action of
the cold-rolled steel

● holds a circular cross
section under any bend,
Light weight, easy
installations

The Philippine Electrical Code provides that rigid non-metallic conduit may
be used under the following conditions:

1. Concealed in floors, walls and ceilings
2. Direct earth burial or underground
3. 300 mm in trench below 50mm thick concrete or equivalent
4. 600 mm under streets, highways, roads, alleys, driveway and parking lots
5. 460 mm under driveways and parking lots of single and two family dwelling

units
6. 460 mm under airport runways, including adjacent areas where

trespassing prohibited

7. In locations subject to severe corrosive influences and where subject
chemicals for which the materials are specifically approved

8. Cinder fill
9. In wet locations, provided water is prevented from entering the conduit
10. In dry and damp locations

The Philippine Electrical Code prohibits the use of rigid non-metallic
conduit under the following conditions:

1. Hazardous (Classified) Locations
2. Support of fixtures
3. Physical Damage. Where subject to physical damage unless identified for

such use.
4. Ambient Temperature. Where subject to ambient temperatures in excess

of 50oC unless posted otherwise
5. Insulation Temperature Limitations. For conductors whose insulation

temperature limitations would exceed those for which the conduit is listed.
6. Theaters and Similar Locations.

Sub-Topic 2.1

● Elbow
● Offset bend
● Round saddle bend
● Square saddle bend

Type Description

● Elbow 90o bend

● Offset bend ● Offset bend is less than
90o bend, it is used when

the conduit crosses an

obstacle or when the

conduit is entering an

electrical box

● Round ● Round saddle bend is
saddle used when the conduit run
bend across circular objects like
pipes.

● Square Square saddle bend is Obstacle
saddle similar to round saddle, it is ee
bend used when the conduit run

across rectangular
obstacles. Square saddle is

just a combination of two
offset bends.

Sub-Topic 2.2 Types of Bend Defects

● Burned
● Kinks or groove
● The diameter of the conduit is greatly reduced due to improper bending

procedure

Type Description

● Burned ● Conduits change of
color

● Kinks or ● The diameter of the
groove conduit is slightly
reduced due to improper
bending procedure

Kinks

● The ● The diameter of the
diameter of conduit is greatly
the conduit reduced due to improper
is greatly bending procedure
reduced

Bend 90o Elbow (Rigid Nonmetallic)
Purpose: To become familiar of 90o Bend Elbow of Rigid Nonmetallic Conduit
Procedures:

Prepare the necessary tools, materials and equipment's.

1. Wear appropriate PPE.

2. Draw a right angle on the floor
using your try square and
chalk. This will serve as your
guide when forming your
conduit into 90o angle. (A tile
on the floor can serve as a
guide.)

3. If you are in a room with a

tiled floor, you can use it as
your guide for 90o angle.

4. Draw an arc near the corner
with a radius of 100 mm; this
will aid you in forming your
elbow correctly.

100 mm

5. Mark off 200 mm from the end
of PVC pipe. This will be the
center of your elbow bend.

6. Plug-in the heat gun and
apply heat to the conduit.
Apply heat 100mm on both
sides of your marking. Apply
heat evenly by turning over
the conduit while swaying
your heat gun back and forth
to avoid kinks during bending.

7. Notice that when the conduit
is softening, it will sag as
shown.

9. If the conduit is soften, turn off
the heat gun and bend the PVC
to the desired shape using your
arc and 90o angle guide drawn
on the floor.

8. If the desired shape is formed,
damp the conduit with wet rug
to harden it immediately. (You
can use your foot to hold one
end of the conduit while
wiping.)

10.Perform housekeeping.

Bend 90o Elbow (Rigid metallic)
Purpose: To become familiar of 90o Bend Elbow of Rigid Metallic Conduit
Procedures:
1. Let AB be the required length from one end of the conduit to the point
perpendicular to the bend. (Fig 4a)
2. Measure and mark length AB and B1 (See Mark Back Table below) on the
conduit. (Fig 4b)
3. Place points B1 perpendicular to the flat edge of the conduit bender’s former
with end A pointing away from you.

4. Set bottom edge of roller housing against the appropriate mark.
5. Pull the conduit bender’s loading arm down to produce the 90º bend on the
conduit.
6. Check the conduit for the required bend.
7. Measure and cut BC to the required length.
8. Thread half coupler length on both ends, A and C.
9. Remove all burrs using a reamer.

Offset Bend (Rigid Nonmetallic Conduit)
Purpose: To become familiar of Offset Bend of Rigid Nonmetallic Conduit
Procedures:

1. Prepare the necessary tools, materials and equipment's.
2. Wear appropriate PPE.

3. Measure the elevation of the
obstruction. In this case,
let’s use this wooden box

Note: Remember, offset
bent is used if the conduit
crosses an obstruction.

4. Draw the depth of elevation
on the floor as shown in the
figure using your try square
and chalk. This will guide
you how high your offset
bend would be.

5. You should have two lines
as shown in the figure.

6. Mark off 100 mm from the
end of PVC pipe. This will
be the center of the first
bend of the offset.

7. Put another mark of about
200 mm from your first
marker.

8. Plug-in the heat gun and
apply heat to the conduit.
Apply heat between your
markers. Apply heat evenly
by turning over the conduit
while swaying your heat gun
back and forth to avoid kinks
during bending.

If the conduit is soften, turn off
the heat gun and bend the

PVC to the desired shape
using your guide drawn on the
floor. Pull the left portion of
the conduit while pushing the
other end.
9. If the desired shape is

formed, damp the conduit
with wet rug to harden it
immediately. (You can use
your foot to hold one end of
the conduit while wiping.)

10. Your bend should look like
this.

Offset Bend (Rigid Metallic Conduit)
Purpose: To become familiar of Offset Bend of Rigid Metallic Conduit
Procedures
1. Measure 80 mm from end of conduit to point B and 70 mm from point B to point
C. (Fig 5a)
2. Place point B onto the edge of the former and bend a small angle on the
conduit. (Fig 5b)
3. Turn the conduit 180º, place point C onto the end of the former and bend the
conduit so that both ends of conduit are parallel to each other. (Fig 5c)
4. Check the offset for the required height of the knockout of the accessory box.
5. If the offset is too low or too high, place the conduit at the original markings and
adjust the bend to the required height. Note: A greater or smaller angle of bend
will increase or decrease the height respectively.

Saddle Bend (Rigid Metallic Conduit)
Purpose: To become familiar of Saddle Bend of Rigid Metallic Conduit
Procedures
Bend saddles are often used to cross or saddle a small obstruction that would
prevent the electrician from installing conduit in a straight line
1. Measure the distance from the end of the conduit to be bent to the center of the
object to saddle. Place mark on conduit at distance to center of object.

Square Saddle Bend (Rigid Metallic Conduit)
Purpose: To become familiar of Square Saddle Bend of Rigid Metallic Conduit
Procedures
1. Draw the outline of the bridge bend (Fig 8) on a flat surface.
2. Measure and mark mid-point of conduit length, C
3. Measure and mark points D, D1, E and E1 from point C as shown in Fig 8.
(Refer to Mark Back Table in page 4-2.)
4. Bend 30º at points D1 and E1. (Fig 8a) Note: Ensure that point C is placed
towards the back of the bender.
5. Check the bend against the outline and make any necessary adjustments.
6. With the help of the outline, mark points B, B1, F and F1. (Fig 8b)

7. Bend 30º at B1 and F1. (Figs 8c and 8d)
8. Check the bend against the outline and make any necessary adjustments.