Chapter 12 – Raceway Installation
Chapter 12
Raceway Installation
1
Chapter 12 – Raceway Installation
Objectives
• Select an appropriate raceway size and type for
a residential application.
• Demonstrate an understanding of the proper
techniques for cutting, threading, and bending
electrical conduit for residential applications.
• Demonstrate an understanding of the proper
installation techniques for common raceway
types used in residential wiring.
• Demonstrate an understanding of the common
installation techniques for installing conductors
in an installed raceway system.
2
Chapter 12 – Raceway Installation
Selecting the Appropriate
Raceway Type and Size
• Branch-circuit installation using a raceway wiring
method is seldom used.
• Cable wiring methods are easier to install than
raceway wiring methods and this is the main
reason why most houses are wired using as little
conduit as possible.
• However, some areas of the country require that
all wiring in a house be installed in a raceway
wiring method.
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Chapter 12 – Raceway Installation
Selecting the Appropriate
Raceway Type and Size
• Use individual conductors when installing a circuit
in a raceway wiring method.
• It is common wiring practice to install a green
insulated equipment grounding conductor in every
raceway.
• The most common raceway type used for branch-
circuit installation is EMT.
– EMT is relatively easy to bend and connect.
– EMT is much less expensive than other metal
raceways.
4
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Article 344 covers the installation requirements for
Rigid Metal Conduit (RMC).
– RMC is a threadable 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 with appropriate fittings.
– RMC is generally made of steel with a protective galvanized
coating.
– It can be used in all atmospheric conditions and
occupancies.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Section 344.22 states that the number of
conductors or cables allowed in RMC must not
exceed that permitted by the percentage fill
specified in Table 1, Chapter 9 in the NEC®.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Table 1 of Chapter 9 specifies the maximum fill
percentage of a conduit or tubing.
– For an application where only two conductors are installed,
the conduit cannot be filled to more than 31% of the
conduit’s cross-sectional area.
– If three or more conductors are to be installed (a common
practice), the conduit cannot be filled to more than 40% of
its cross-sectional area.
– If the conductors being installed are all of the same wire
size and have the same insulation type, use Annex C.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Annex C is located in the back of the NEC® and,
through 12 sets of tables, indicates the maximum
number of conductors that are the same size and
have the same insulation permitted in a conduit or
tubing.
– The maximum number of conductors allowed in a
conduit, according to Annex C, takes into account the
fill percentage requirements of Table 1, Chapter 9.
– No additional calculations are necessary.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Determine the maximum number of conductors
of different sizes and different insulations in a
conduit.
– Use Table 4, Chapter 9, to get the usable area of a
specific size and type of conduit or tubing.
– Use Table 5, Chapter 9, to get the required area of
each conductor size with a specific insulation type
used in the conduit.
9
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Section 344.24 requires that when bending RMC, the
bends must be made so that the conduit is not damaged
and the internal diameter of the conduit is not effectively
reduced.
• Section 344.26 limits the
number of bends in one
conduit run from one box to
another to no more than
360 degrees total.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• When cutting RMC, Section 344.28 requires all
cut ends to be reamed or otherwise finished to
remove rough edges.
• Install RMC as a complete system as required in
Section 300.18(A) and securely fasten it in place
and support it in accordance with Section
344.30(A) and (B).
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Section 344.46 states that
where a rigid metal
conduit enters a box,
fitting, or other enclosure,
a bushing must be
provided to protect the
wire from abrasion unless
the design of the box,
fitting, or enclosure is
made so it already gives
protection.
12
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RMC
• Section 344.60, RMC is permitted as an
equipment grounding conductor.
– If the RMC is attached correctly at each electrical
enclosure and any couplings used to connect lengths
of RMC together are properly tightened, the conduit
itself can be the equipment grounding conductor and
there is no need to run an additional grounding
conductor in the conduit along with the regular circuit
conductors.
13
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: IMC
• Article 342 covers the installation requirements
for Intermediate Metal Conduit (IMC).
– IMC is a steel threadable raceway of circular cross section
designed for the physical protection and routing of
conductors and cables.
– It is uses as an equipment grounding conductor when
installed with associated couplings and appropriate fittings.
– IMC is a thinner-walled version of rigid metal conduit used
in all locations where rigid metal conduit is permitted to be
used.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: IMC
• Section 342.22 covers the requirements for
determining the maximum number of conductors
allowed in a specific size of IMC.
– The procedures are the same as for RMC with the
exception of using Table C4 in Annex C when determining
the maximum number of conductors that are all the same
size and with the same insulation type.
– Also, use the IMC section of Table 4 in Chapter 9 when
determining the minimum size IMC for conductors of
different sizes with different insulation types.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: IMC
• All other NEC® installation requirements for IMC,
including support, are the same as for RMC and
were presented earlier.
16
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: EMT
• Article 358 covers the installation requirements
for Electrical Metallic Tubing (EMT).
– EMT is an unthreaded thin-wall raceway of circular
cross section designed for the physical protection and
routing of conductors and cables.
– It is used as an equipment grounding conductor when
installed using appropriate fittings.
17
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: EMT
• Section 358.22 covers the requirements for
determining the maximum number of conductors
allowed in a specific size of EMT.
– The procedures used are exactly the same as for RMC
and IMC with the exception of using Table C1 in Annex C
when determining the maximum number of conductors that
are all the same size and with the same insulation type.
– Also, use the EMT section of Table 4 in Chapter 9 when
determining the minimum size EMT for conductors of
different sizes that have different insulation types.
18
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: EMT
• Section 358.24 requires bends in EMT to be
made so that the tubing is not damaged and the
internal diameter of the tubing is not effectively
reduced.
• Like all of the other circular raceways discussed
in this chapter, Section 358.26 does not allow
more than the equivalent of 360 degrees total
bending between termination points of EMT.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: EMT
• Like RMC and IMC, Section 358.28 requires all
cut ends of EMT to be reamed or otherwise
finished to remove rough edges.
20
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: EMT
• Similar to both RMC and IMC, Section 358.30
requires EMT to be installed as a complete
system and to be securely fastened in place and
supported.
– EMT must be securely fastened in place at least every 10’
(3 m).
– Between termination points, EMT must be securely
fastened within 3’ (900 mm) of each outlet box, junction
box, device box, cabinet, conduit body, or other tubing
termination.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: EMT
– Exception No. 2 to Section 358.30(A):
• States that for concealed work in finished buildings or pre-
finished wall panels where such securing is impracticable,
unbroken lengths (without a coupling) of EMT permitted to be
fished.
– Section 358.30(B):
• Allows horizontal runs of EMT supported by openings
through framing members at intervals not greater than 10’ (3
m) and securely fastened within 3’ (900 mm) of termination
points.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: EMT
• Section 358.42 requires couplings and
connectors used with EMT to be made up tight.
• According to Section 358.60, EMT is also
permitted as an equipment grounding conductor.
23
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: FMC
• Article 348 covers the installation requirements
for Flexible Metal Conduit (FMC).
– FMC is a raceway of circular cross section made of
helically wound, formed, interlocked metal strip.
– Many electricians often refer to this raceway type as
Greenfield.
– FMC is appropriate for use indoors where a need for
flexibility at the connection points is required.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: FMC
• Section 348.22 covers the requirements for
determining the maximum number of conductors
allowed in a specific size of FMC.
– The procedures used are exactly the same as for the
raceways we previously discussed, with the exception of
using Table C3 in Annex C when determining the
maximum number of conductors that are all the same size,
with the same insulation type.
– Also, use the FMC section of Table 4 in Chapter 9 when
determining the minimum size FMC for conductors of
different sizes that have different insulation types.
25
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: FMC
– One other difference:
• Use Table 348.22 when determining the maximum number of
conductors in a 3/8” trade size FMC.
– This table must be used because the 3/8” size is not included in
Table C3 of Annex C.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: FMC
• As with other raceways, Section 348.24 and
Section 348.26 state that a run of flexible metal
conduit installed between boxes, conduit bodies,
and other electrical equipment, is not permitted
to contain more than the equivalent of 360
degrees total.
• Proper shaping and support of this flexible wiring
method will ensure that conductors can be easily
installed or taken out at any time.
27
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: FMC
• Section 348.28 requires all cut ends to be
trimmed or otherwise finished to remove rough
edges, except where fittings that thread into the
convolutions (so called inside fittings) are used.
• Section 348.30 gives the securing and
supporting requirements.
– They are exactly the same as for Type AC cable and Type
NM cable.
28
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: FMC
• According to Section 348.60, FMC can be used
as a grounding means if it is not longer than 6’
(2 m).
– Any installation of FMC over 6’ (2 m) in length will
require an installed grounding conductor.
– An additional equipment grounding conductor is
always required where FMC is used for flexibility.
29
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: LFMC
• Article 350 covers the installation requirements
for Liquidtight Flexible Metal Conduit (LFMC).
– Raceway of circular cross section having an outer
liquidtight, nonmetallic, sunlight-resistant jacket over
an inner flexible metal core with associated couplings,
connectors, and fittings for the installation of electric
conductors
– Intended for use in wet locations for connections to
equipment located outdoors such as air conditioning
equipment
30
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: LFMC
• Section 350.22 covers the requirements for
determining the maximum number of conductors
allowed in a specific size of LFMC.
– The procedures are exactly the same as for the raceways
we have previously discussed, with the exception of using
Table C7 in Annex C when determining the maximum
number of conductors that are all the same size and with the
same insulation type.
– Use the LFMC section of Table 4 in Chapter 9 when
determining the minimum size LFMC for conductors of
different sizes that have different insulation types.
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Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: LFMC
– One other difference:
• Use Table 348.22 when determining the maximum number of
conductors in a 3/8” trade size LFMC.
32
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: LFMC
• As with Flexible Metal Conduit, Sections 350.24
and 350.26 state that a run of liquidtight flexible
metal conduit installed between boxes, conduit
bodies, and other electrical equipment is not
permitted to contain more than the equivalent of
360 degrees total.
• The securing and supporting requirements are
given in Section 350.30.
– Exactly the same as for Flexible Metal Conduit.
33
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: LFMC
• According to Section 350.60, FMC can be used
as a grounding means if it is not longer than 6’
(2 m).
– Any installation of FMC over 6’ (2 m) in length
requires an installed grounding conductor.
– An additional equipment grounding conductor is
always required where FMC is used for flexibility.
34
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Article 352 covers the installation requirements
for Rigid Nonmetallic Conduit (RNC).
– Nonmetallic raceway of circular cross section, with
integral or associated couplings, connectors, and
fittings for the installation of electrical conductors.
– Two types commonly used:
• Schedule 40
• Schedule 80
35
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Schedule 40 RNC
– Suitable for underground use by direct burial or
encasement in concrete.
– Suitable for aboveground use indoors or outdoors
exposed to sunlight and weather where not subject to
physical damage (unless marked “Underground Use
Only” or equivalent wording).
36
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Schedule 80 RNC
– Suitable for use wherever Schedule 40 conduit may
be used.
– Marking “Schedule 80” identifies conduit as suitable
for use where exposed to physical damage.
37
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Section 352.22 covers requirements for
determining maximum number of conductors
allowed in a specific size of RNC.
– The procedures used are the same as for the other solid
length conduits discussed with the exception of using Table
C9 in Annex C when determining the maximum number of
conductors that are all the same size with the same
insulation type.
– Use the RNC section of Table 4 in Chapter 9 when
determining the minimum size RNC for conductors of
different sizes with different insulation types.
38
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Section 352.24 requires that when bending RNC,
bends must be made so the conduit is not
damaged and the internal diameter of the conduit
is not effectively reduced.
• Field bends must be made only with bending
equipment identified for the purpose.
39
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Section 352.26 limits the number of bends in one
conduit run from one box to another to no more
than 360 degrees.
• When cutting RNC, Section 352.28 requires all
cut ends to be reamed or otherwise finished to
remove rough edges.
• Section 352.30 requires RNC to be installed as a
complete system and to be fastened to permit
movement from thermal expansion or
contraction.
40
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• RNC must be securely fastened and supported.
– Must be fastened within 3’ (900 mm) of each outlet box,
junction box, device box, conduit body, or other conduit
termination.
– Must be supported as required in Table 352.30(B)
– Horizontal runs of RNC are permitted when
• Supported by openings through framing members at
intervals not exceeding those in Table 352.30(B) and
securely fastened within 3’ (900 mm) of termination
points.
41
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Expansion fittings for RNC are covered in Section
352.44.
– They are required to compensate for thermal expansion and
contraction where the length change, in accordance with
Table 352.44(A) or (B), is expected to be ¼” (6 mm) or
greater in a straight run between securely mounted items
such as boxes, cabinets, elbows, or other conduit
terminations.
42
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Expansion fittings are generally provided in
exposed runs of rigid nonmetallic conduit in the
following instances.
– The run is long.
– The run is subjected to large temperature variations
during or after installation.
– Expansion and contraction measures are provided for
the building or other structures.
43
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: RNC
• Section 352.46
– Where RNC enters a box, fitting, or other enclosure, a bushing
must be provided to protect the wire from abrasion unless the
design of the box, fitting, or enclosure affords equivalent
protection.
• Section 300.4(F)
– An insulated bushing (like plastic) must be used for the
protection of conductors sizes #4 AWG and larger that are
installed in conduit.
• Section 352.60
– RNC is made of nonconductive material (PVC).
– A separate equipment grounding conductor must always be
installed in the conduit.
44
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: ENT
• Article 362 covers the installation requirements
for Electrical Nonmetallic Tubing (ENT).
– ENT is a nonmetallic pliable corrugated raceway of
circular cross section with integral or associated
couplings, connectors, and fittings for the installation
of electric conductors.
– It is composed of a material that is resistant to
moisture and chemical atmospheres and is also flame
retardant.
45
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: ENT
• Section 362.22 covers the requirements for
determining the maximum number of conductors
allowed in a specific size of ENT.
– The procedures are exactly the same as for Electrical
Metallic Tubing (EMT) with the exception of using Table
C2 in Annex C when determining the maximum number of
conductors that are all the same size and with the same
insulation type.
– Use ENT section of Table 4 in Chapter 9 to determine
minimum size ENT for conductors of different sizes with
different insulation types.
46
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: ENT
• Section 362.24 requires bends in ENT to be
made so that the tubing is not damaged and the
internal diameter of the tubing is not effectively
reduced.
• Section 362.26 does not allow more than the
equivalent of 360 degrees total bending between
termination points.
• Section 362.28 requires all cut ends of ENT to
be reamed or otherwise finished to remove
rough edges.
47
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: ENT
• Section 362.30 covers securing and supporting
of ENT.
– ENT must be installed as a complete system and be
securely fastened in place and supported.
• ENT must be securely fastened at intervals not exceeding 3’
(900 mm).
• ENT must be securely fastened in place within 3’ (900 mm)
of each outlet box, device box, junction box, cabinet, or fitting
where it terminates.
• Where ENT is run on the surface of framing members, it is
required to be fastened to the framing member every 3’ (900
mm) and within 3’ (900 mm) of every box.
48
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: ENT
– Horizontal runs of ENT are permitted when:
• Supported by openings in framing members at
intervals not exceeding 3’ (900 mm) and securely
fastened within 3’ (900 mm) of termination points.
49
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: ENT
• Section 362.46
– Where ENT enters a box, fitting, or other enclosure, a
bushing must be provided to protect the wire from
abrasion unless the design of the box, fitting, or
enclosure is such as to afford equivalent protection.
• Section 300.4(F)
– Use an insulated bushing (like plastic) for the
protection of conductors sizes #4 AWG and larger
that is installed in conduit.
50
Chapter 12 – Raceway Installation
Raceway Type Installation
Requirements: ENT
• Since ENT is made of a nonconductive material
(PVC), Section 362.60 requires a separate
equipment grounding conductor to always be
installed in the conduit.
51
Chapter 12 – Raceway Installation
Cutting Conduit
• Solid-length metal conduit, like Rigid Metal
Conduit, Intermediate Metal Conduit, and
Electrical Metallic Tubing, can be cut to length
by using one of the following tools.
– Pipe cutter
– Tubing cutter
– Portable bandsaw
– Hacksaw
52
Chapter 12 – Raceway Installation
Cutting Conduit
• The ends of cut lengths of RMC and IMC will
also have to be threaded.
53
Chapter 12 – Raceway Installation
Cutting Conduit
• RNC can be cut using a hacksaw or with saws
equipped with special blades for PVC.
• FMC and LFMC are usually cut with a hacksaw.
• ENT can also be cut with a hacksaw, but special
nonmetallic tubing cutters that look like big
scissors are available.
54
Chapter 12 – Raceway Installation
Bending Conduit
• Bending conduit is definitely a skill that improves
with practice.
• The most common electrical conduit installed in
houses is EMT and, for this reason, the
discussion that follows on conduit bending will
focus on EMT.
• The bending techniques described will also
apply to the other types of circular metal
raceway such as RMC and IMC.
55
Chapter 12 – Raceway Installation
Bending Conduit
• 90º bend or stub-up
– Most common type.
• Back-to-back bend
– Distance is measured
between the outside
diameters of two sections of
the pipe.
56
Chapter 12 – Raceway Installation
Bending Conduit
• Offset bend
– Two equal bends result in the direction of the conduit
being changed to avoid an obstruction blocking the
conduit run.
57
Chapter 12 – Raceway Installation
Bending Conduit
• Saddle bend
– Similar to offset bend
• Allows conduit run to go around an obstruction.
– Difference:
• Goes over the obstruction rather than around it.
– Two styles:
• Three-point saddle
• Four-point saddle
58
Chapter 12 – Raceway Installation
Bending Conduit
• Box offset bend
– Smaller version of regular offset bend.
– Used when conduits enter a box or other electrical
enclosure that is surface mounted.
59
Chapter 12 – Raceway Installation
Bending Conduit
• EMT is bent in the field using either a hand
bender, a hydraulic bender, or an electric
bender.
• Bend sizes ½” through 1 ¼” with a hand bender.
• Use a hydraulic or electric power bender for
larger sizes.
• Since most EMT installed in houses will be ½”,
¾”, or 1” trade sizes, we will keep our discussion
focused on bending with a hand bender.
60
Chapter 12 – Raceway Installation
Raceway Installation
Using EMT
• When EMT is used, use only metal electrical
boxes.
• Connect the EMT to the boxes with approved
fittings, called connectors.
– The set-screw type of connector is used most often
because of its ease of installation and lower cost.
• When lengths of EMT need to be coupled
together, use only approved couplings.
– Just like the connectors, couplings are available in a
set-screw or a compression type.
61
Chapter 12 – Raceway Installation
Raceway Installation
Using EMT
• EMT is an approved grounding method, and as
such, does not always require an equipment
grounding conductor to be run in the raceway
with the other circuit conductors.
• Most electricians will run a green insulated
grounding conductor in the raceway, though it is
not required.
62
Chapter 12 – Raceway Installation
Raceway Installation
Using EMT
• Electricians choose the conductor insulation color
for the conductors they install in the raceway.
– For a 120-volt branch circuit, use a white insulated wire
and a black insulated wire.
– For a straight 240-volt circuit (like an electric water
heater), use two black conductors or a black and a red
conductor.
– If the circuit is a 120/240-volt circuit (like an electric
clothes dryer), run a white insulated wire, a black
insulated wire, and a red insulated wire.
63
Chapter 12 – Raceway Installation
Raceway Installation
Using EMT
• EMT can be installed
– Though drilled holes in studs, joists, and rafters like
Type NM cable.
– On a wall or a ceiling’s finished surface.
64
Chapter 12 – Raceway Installation
Raceway Conductor
Installation
• Conductors are usually pulled into the conduit, but in
shorter runs between electrical boxes.
• Conductors may be pushed through the raceway.
• Conductors are taken off spools in a way that results in
the conductors coming off the spools easily and not
becoming tangled with each other.
– One of the easiest ways to do this is to use a wire cart that allows
several spools of wire to be put on at one time.
65
Chapter 12 – Raceway Installation
Raceway Conductor
Installation
• If the length of conduit between boxes is fairly
long, use a fish tape.
– Pull the fish tape out of its reel. Insert it into a raceway
and push it through until it comes out at a box location.
– The fish tape will have a hook on the end of it.
• Attach the conductors to the fish tape end.
– While one electrician pulls the conductors slowly off the
spools, another electrician will pull the fish tape with the
attached conductors back through the raceway.
66