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Guidelines for Installing Steel Conduit/Tubing Guidelines for Installing
Steel Conduit/Tubing 1.
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
2.
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
3.
General Product Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
3.1
Steel Conduit and Tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
3.2
Manufactured Elbows, Nipples, and Couplings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4.
General Installation Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4.1
Conduit Cutting and Threading Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4.2
Bending Galvanized Conduit and Tubing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4.3
Fittings for Use with RMC, IMC and EMT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
4.4
Support of Raceways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.5
Firestopping and Fire Blocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.6
Corrosion Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.7
Equipment Grounding Using Steel Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.
Specific Installation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5.2
Raceways Installed in Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5.3
Communication Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.4
Underground Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.5
Verification of Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
6.
Installation Practices for PVC-Coated Conduit and Fittings . . . . . . . . . . . . . . . . . . . . . . . . .22
6.1
Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
6.2
Clamping (Vising) PVC-Coated Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
6.3
Cutting and Threading PVC-Coated Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
6.4
Bending PVC-Coated Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
6.5
Installing PVC-Coated Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
6.6
Patching Damaged Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
6.7
Equipment Grounding and Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Annex A: Threading Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Annex B: Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Annex C: Reference Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Table of Contents
1
This standard covers the installation of steel rigid
metal conduit (RMC), steel intermediate metal con-
duit (IMC), and steel electrical metallic tubing
(EMT). Conduit with a supplementary PVC coating
is also included. These conduits are used as raceway
systems for electrical wiring in residential, commer-
cial, and industrial occupancies. This standard
includes information on fittings and other applicable
accessories necessary for a quality installation of
these raceways. All information in this publication is
intended to comply with the National Electrical
Code® (NFPA Standard 70). Installers should always
follow the NEC, applicable state and local codes, and
manufacturers instructions when installing electrical
products and systems.
Installations must be performed in a neat and work-
manlike manner. This is one of the most basic and
important requirements for electrical wiring in the
National Electrical Code®. It is essential that the
installer be concerned, informed, and have pride in
the finished product. Maintaining the effectiveness of
Code requirements depends on selecting the right
product for the specific job, good installation work-
manship, and proper maintenance during the life
cycle.
This standard is intended to enhance electrical safety
by (1) aiding the installer in meeting the neat and
workmanlike requirements, (2) reducing future
repair needs, (3) providing for future expansion to
avoid electrical overload, (4) creating an installation
which will protect the wire conductors from mechan-
ical abuse, (5) and providing electrical continuity of
the raceway system.
1. Scope 2
Alternate
A coating(s), other than one
corrosion
consisting solely of zinc, which,
protection
upon evaluation, has demon-
strated the ability to provide the
level of corrosion resistance
required on the exterior of the
conduit. It is not prohibited that
the coatings include zinc.
Approved
Acceptable to the authority hav-
ing jurisdiction.
NOTE: The authority having
jurisdiction is most often the
electrical inspector, but could be a
project manager or other final
approval authority.
Authority
The organization, office, or indi-
having
vidual with the authority
jurisdiction
to determine which code
requirements apply, how they
are to be interpreted, and who
gives final approval to the elec-
trical installation. Some exam-
ples are the electrical inspector
or other government entity and
insurance underwriters.
Bend
A curvature of the conduit or
tubing made so the raceway will
fit a specific geometric location.
This can be a factory elbow or a
field bend of the raceway.
Circuit loading
Concentration of circuits in one
raceway.
Conduit
Interface between conduit or
connection
tubing and other equipment.
Conduit joint
Coupling of two pieces of con-
duit or tubing, or coupling a
length of conduit or tubing to a
bend.
NOTE: One of the most impor-
tant elements of an electrical
installation.
Coupling, integral
A coupling meeting the require-
ments of UL 514B which is
assembled to the conduit, tub-
ing, or elbow during manufac-
ture and is not readily remov-
able. The integral coupling of
electrical metallic tubing is a
belled end with set screws.
Coupling,
As applied to IMC or RMC
standard conduit
this is a threaded, straight-
tapped means of joining two
pieces of conduit. Such cou-
pling meets the requirements of
the applicable UL conduit stan-
dard.
Equipment
As defined in the NEC. In
grounding
addition, it is the path by which
conductor
a fault is transmitted to the
overcurrent protection device.
NOTE: Steel conduit and tubing
are called equipment grounding
conductors, as are copper or alu-
minum wire.
2. Glossary (as used in this Standard) Firestopping
Using approved materials (gen-
erally detailed by building codes
or specifications) which fill the
opening around the conduit to
prevent the spread of fire and
smoke and assure the fire rating
of the wall, floor, or ceiling
being penetrated is not reduced.
Fire-rated
Construction materials
assemblies
assembled together, then tested
and rated for ability to inhibit
the spread of fire for a specified
period of time under specific
test conditions. The rating is
expressed in hours e.g. 1 hour, 2
hour, etc. Information can be
found in various laboratory
listing directories.
Fitting, threadless
A fitting intended to secure,
without threading, rigid or
intermediate metal conduit or
electrical metallic tubing to
another piece of equipment
(connector) or to an adjacent
length of conduit or tubing
(coupling).
Galvanized
Protecte