6. Learning Content
6
PERFORM ROUGHING-IN ACTIVITIES FOR
COMMUNICATION AND DISTRIBUTION SYSTEM (RC)
LO 1. Install electrical metallic tubing
1.1 Prepare tools/equipment and materials
needed for the installation of electrical
metallic tubing in line with job requirements
7. Learning Objectives
7
At the end of the learning activity, the learners will be
able to:
1. Identify Electrical Metallic Tubing as per PEC
provision.
2. Prepare Electric Metallic Tubing as per PEC
provision.
3. Understand the importance of good workmanship
and following the codes set by the authority.
8. 8
PVC Conduit and Fittings EMT Conduit and Fittings
Rigid Steel Conduit
and Fittings
9. 9
Electrical Metallic
Tubing (EMT)
Rigid Metal Conduit
(RMC)
PVC Conduit
Made of Metal Made of Metal Made of Plastic
Lightweight Heavy Lightweight
Thin Wall Thick Wall Thin Wall
Unthreaded Threaded Unthreaded
Screws are used to
connect to fittings
Have threads to
connect to fittings
Adhesive or glue is
used for connections
Comparison of Properties of Conduit Types
10. PEC Provision on Electrical Metallic
Tubing
10
PEC article 3.58 – Electric Metallic Tubing: Type EMT
358.1.2 Definition.
Electric Metallic Tubing (EMT). An unthreaded thin
wall raceway of circular cross section designed for the
physical protection and routing of conductors and
cables and for use as an equipment grounding
conductor when installed utilizing appropriate fittings.
11. 11
358.2.3 Uses Permitted.
(A)Exposed and Concealed. The use of EMT shall be
permitted for both exposed and concealed work for
the following:
(1) In concrete, in direct contact with the earth or in
areas subject to severe corrosive influences where
installed in accordance with 3.58.2.1(B).
(2) In dry, damp, and wet locations
(3) In any hazardous (classified) locations as permitted
by other articles in this Code.
12. 12
(B) Corrosive Environments
(1) Galvanized steel and stainless steel EMT, elbows,
and fittings shall be permitted to be installed in
concrete, in direct contact with the earth, or in areas
subject to corrosive influences where protected by
corrosion protection and approved as suitable for the
condition.
(2) Supplementary Protection of Aluminum EMT.
Aluminum EMT shall be provided with approved
supplementary corrosion protection where encased in
concrete or in direct contact with the earth.
13. 13
(C) Cinder Fill. Galvanized steel and stainless steel
EMT shall be permitted to be installed in cinder
concrete or cinder fill where subject to permanent
moisture when protected on all sides by a layer of non-
cinder concrete at least 50 mm thick or when the tubing
is installed at least 450 mm under the fill.
(D) Wet Locations. All supports, bolts, straps, screw,
and so forth shall be of corrosion-resistant materials or
protected against corrosion by corrosion-resistant
materials.
14. 14
358.2.1 Uses Not Permitted. EMT shall not be used
under the following conditions:
(1) Where subject to severe physical damage
(2) Where protected from corrosion solely by enamel.
358.2.11 Size.
(A)Minimum. EMT smaller than metric designator 16
(trade size ½) shall not used.
(B)Maximum. The maximum size of EMT shall be
metric designator 103 (trade size 4).
15. 15
358.2.13 Number of Conductors. The number of
conductors shall not exceed that permitted by the
percentage fill specified in Table 10.1.1.1.
Number of Conductors
and / or Cables
Cross Sectional Area (%)
1 53
2 31
Over 2 40
Table 10.1.1.1 Percent of Cross Section of Conduit
and Tubing for Conductor
17. 17
358.2.15 Bends – How Made. Bends shall be made so
that the tubing is not damaged and the internal
diameter of the tubing is not effectively reduced. The
radius of the curve of any field bend to the centerline of
the tubing shall not be less than shown in Table
10.1.1.2 for one shot and full shoe benders.
18. 18
Conduit or Tubing Size
(mm)
One Shot and Full Shoe
Bender (mm)
15 100
20 115
25 145
32 180
40 210
50 240
65 265
Table 10.1.1.2 Radius of Conduit and Tubing Bends
19. 19
358.2.17 Bends – Number in One Run. There shall be
not more than the equivalent of four quarter bends (360
degrees total) between pull points, for example, conduit
bodies and boxes.
21. 21
358.2.21 Securing and Supporting.
(A) Securely Fastened. EMT shall be securely fastened
in place at intervals not exceeding 3000 mm (10 ft). In
addition, each EMT run between termination points
shall be securely fastened within 900 mm (3 ft.) of each
outlet box, junction box, device box, cabinet or conduit
bodies.
23. 23
(B) Supports. Horizontal runs of EMT supported by
openings through framing members at intervals not
greater than 3000 mm and securely fastened within
900 mm of termination points shall be permitted.
24. 24
Figure 1. EMT (thin-wall) conduit
EMT conduit comes in 10-foot lengths. A breakdown of
the sizes of EMT conduit in inches follows: 1/2, 3/4, 1,
1 1/2, 2, 2 1/2, 3, 3 1/2, and 4.
26. Application
26
Electrical Metallic Tubing (EMT), is a familiar sight in
commercial and industrial facilities. It is seldom used in
residential wiring where application is mostly for
exposed installation for enhanced protection of electrical
wiring.
27. Application
27
Based on a given Lighting Layout, draw a Conduit
Layout using electrical metallic tubing and its fittings.
28. Application
28
Performance Rubrics
Criteria 3pts 2pts 1pt
Appearance Drawing is creative
or artistic
Some drawings are
moderately creative
or artistic
Most of the drawings
are not creative and
artistic
Time
Management
Able to finish the
activity ahead of
time
Able to finish the
activity exact time to
the given period
Able to finish the
activity after the given
period
Cleanliness Activity sheet has
no marks of any
erasures
Activity sheet has
some marks of
erasures
Activity sheet is messy
or untidy
30. Values
30
Promote safety and protect the community from hazards
that may arise from faulty electrical installation.
31. Assessment
31
Multiple Choice: Choose the best answer. Write the
letter of your choice to your answer sheet.
1. An unthreaded thin wall raceway of circular cross
section designed for the physical protection and routing
of conductors and cables.
A. Rigid Metal Conduit
B. Rigid Non-Metallic Conduit
C. Electrical Metallic Tubing
32. Assessment
32
2. According to PEC requirements how many bends are
allowed in a conduit run?
A. Not more than 360 degrees bend
B. More than 360 degrees bend
C. 450 degrees bend
33. Assessment
33
3. According to PEC what is the allowable percentage fill
of the conduit if the conductor is 2 or more?
A. 53%
B. 31%
C. 40%
34. Assessment
34
4. How much is the minimum bending radius of a
conduit if the size is 20mm?
A. 100mm
B. 115mm
C. 145mm
35. Assessment
35
5. What is the maximum intervals in fastening of
electrical metallic tubing?
A. 1500mm
B. 2000mm
C. 3000mm
