EMT Helpful Info

EMT, Increase Your Knowledge from American Fittings

Electrical metallic tubing (EMT), sometimes called thin-wall, is commonly used instead of galvanized rigid conduit (GRC), as it is less costly and lighter than GRC. EMT itself is not threaded but can be used with threaded fittings that clamp to it. Lengths of conduit are connected to each other and to equipment with clamp-type fittings. Like GRC, EMT is more common in commercial and industrial buildings than in residential applications. EMT is generally made of coated steel, though it may be aluminum.

Electrical metallic tubing (EMT), sometimes called thin-wall, is commonly used instead of galvanized rigid conduit (GRC), as it is less costly and lighter than GRC. EMT itself is not threaded, but can be used with threaded fittings that clamp to it. Lengths of conduit are connected to each other and to equipment with clamp-type fittings. Like GRC, EMT is more common in commercial and industrial buildings than in residential applications. EMT is generally made of coated steel, though it may be aluminum.

Electrical Code Compliance

EMT is covered by Article 358 of the NEC®.
EMT MUST be listed to Underwriters Laboratories Safety Standard UL 797 and meets ANSI C80.3. These standards have been adopted as federal specifications in lieu of WWC 563. EMT is recognized as an equipment grounding conductor by NEC Section 250-118. Documentation for compliance with NEC Article 250 is also available in the GEMI (Grounding and Electro-Magnetic Interference) analysis software and related research studies found at the www.alliedeg.com website.
Installation of EMT shall be in accordance with the National Electrical Code and the UL listing information. Allied EMT islisted in category FJMX. Master bundles conform to NEMA Standard RN2.

EMT Sizing

EMT is available in trade sizes 1/2 through 4, and 10′ and 20′ lengths. Some manufacturers also produce EMT in a range of colors for easy system identification.

EMT Weights and Dimensions

EMT
Trade Size Designator
Nominal Wt. per 100 Ft. (30.5m)
Nominal Outside Diameter
Nominal Wall Thickness
Quantity in Primary Bundle
MASTER BUNDLES
Quantity
Approx. Wt.
Volume
U.S.”
lb.
in.
in.
ft.
ft.
lb.
cu ft.
1/2
30
0.706
0.042
100
7000
2100
28.7
3/4
46
0.922
0.049
100
5000
2300
35.6
1
67
1.163
0.057
100
3000
2010
33.7
1 1/4
101
1.510
0.065
50
2000
2020
35.0
1 1/2
116
1.740
0.065
50
1500
1740
34.2
2
148
2.197
0.065
1200
176
46.7
2 1/2
216
2.875
0.072
610
1318
41.5
3
263
3.500
0.072
510
1341
48.9
3 1/2
349
4.000
0.083
370
1291
48.6
4
393
4.500
0.083
300
1179
48.3
EMT, which is most commonly made of galvanized steel but can be aluminum. EMT is also called “thin-wall” conduit because it is thin and lightweight, especially compared to RMC. EMT is rigid but can be bent with a simple tool called a conduit bender. EMT is installed with couplings and fittings that are secured with a setscrew or compression-type fastener. The tubing is not threaded like RMC is. Common sizes of EMT include 1/2-inch, 3/4-inch, and 1-inch.
It is commonly used for exposed indoor wiring runs in residential and light commercial construction. It must be used with special watertight fittings to be used outdoors in exposed locations.
EMT can be used indoors, outdoors, underground, and in both concealed and exposed applications. IMC has a thinner wall and weighs less than RMC. IMC can be used for the same applications as galvanized RMC. EMT is the lightest-weight steel conduit manufactured.
EMT is made from the highest quality steel, and then it’s galvanized to help prevent corrosion or rusting. Easy to cut or bend and lightweight this conduit will help protect electrical wires and cables from environmental, chemical and mechanical forces for many years.
Anywhere UF cable is exposed above the soil, it must be protected with the conduit. … Not all types of conduit can be buried in the soil. EMT (Electrical Metallic Tubing) and flexible “Raintite” are not considered suitable for burial. Aluminum Rigid will corrode away in certain soils, such as clay, or in moist areas.
When selecting a wiring method, life expectancy is one of the key issues typically considered. Depending upon the installation, part of that consideration concerns the resistance of the product to corrosive environments. Read More. . Tech Info EMT Conduit

COLOR CODED EMT TUBING

EMT Red Fittings, Steel Made in the USA

 

Shown American Fittings Red – EMT Fittings Set Screw

RED Fire Alarm® EMT
• Emergency circuits
• Fire alarm and Security systems
Orange EMT
• Construction/research areas
• Fiber optic systems
• Auto repair/maintenance
Yellow EMT
• High voltage wiring
• Caution areas
• Special equipment
Green EMT
• Hospital and healthcare areas
• Nurse call stations
• Critical circuits
Blue EMT
• Low voltage wiring
• Data com/video
• Network security
Purple EMT
• Specialty wiring systems
• Security systems
Black EMT

• Blends in dark colored areas
White EMT
• Blends in light colored areas
Silver EMT
• Standard Use
• Contemporary architecture

Basics of EMT Fittings

FIRST:

Do not take applications for granted. Many fitting designs look the same but may contain subtle construction differences designed to enhance performance in particular applications. Listed fittings contain required, informative markings and any specific conditions for use. For specific selection and installation guidelines, consult NEMA FB2.10, “Selection and Installation Guidelines for Fittings for Use with Nonflexible Metallic Conduit and Tubing.”

Check out our Video on Die Cast vs Steel Fittings

EMT Fittings for special applications

Threadless fittings intended for use in wet locations are marked “Wet locations” on the fitting or its smallest unit shipping container. Fittings marked “Raintight” are suitable for use in “Wet Locations.” ”Wet Locations” fittings are sometimes referred to as “Raintight.”
A threadless fitting designed for use in wet locations that requires a gasket or sealing ring installed between the fitting and a box shall be installed only with the specific component marked on the fitting’s smallest unit shipping container.
NOTE: “Wet Locations” or “Liquidtight” fittings are not necessarily suitable for use in applications where submersion in water is expected. ”Wet Locations” fittings are not necessarily considered “Liquidtight.” “Liquidtight” fittings are intended for use in typical wet locations and also in “wet” industrial environments which may contain machine oils and coolants.
Threadless fittings intended for embedment in poured concrete are marked “CONCRETE TIGHT” or “Concrete-tight when taped” or ”Wet Locations” on the fitting’s smallest unit shipping container.
NOTE: TAPING is adequate to prevent the entrance of concrete aggregate into the raceway or box. Concrete aggregate consists of cement combined with inert material such as coarse sand. When hardened, such aggregate may be abrasive and might pose a risk of abrading conductor insulation or effectively reducing the area inside the raceway. Fittings listed as ”Wet Locations” are also “Concrete-tight.” The term “Raintight” has been removed from UL 514B as the result of NEC® changes that removed the term in reference to EMT and rigid fittings. The term “Wet Locations” is now required.

EMT  & INSTALLATION:

BEFORE Installing Fittings,  EMT, conduit ends shall:
  • have squarely cut ends, free of internal and external burrs, and circular form as provided from the factory,
  • be free from dirt or foreign matter on the surface of the conduit to be inserted into the fitting, and
  • have the ends of the conduit or tubing assembled flush against the fitting’s end stop. Careful consideration shall be given to the torque applied to the fitting’s securement means.
EMT connectors are permitted to be assembled into threaded entries of boxes, conduit bodies or internally threaded fittings having tapered threads (NPT). EMT fittings designed to NEMA FB 1, “Fittings, Cast Metal Boxes, and Conduit Bodies for Conduit and Cable Assemblies,” have straight threads (NPS). Threaded openings where these fittings are intended to be used are permitted to have either tapered (NPT) or straight (NPS) threads. Care should be taken to ensure that the threaded entry will accommodate a minimum of three full engaged threads of the fitting.
Where a locknut is provided with a fitting as the means of securement to a box or enclosure, the locknut is to be secured by hand-tightening to the enclosure plus 1/4 turn using an appropriate tool.

The National Electrical Manufacturer’s Association (NEMA) stresses the importance of selecting the right fitting for the job. Combining your knowledge of how to do that with Sec. 110-12’s required workmanship will ensure a safe, effective, and permanent installation

Fittings come in several materials, including cast aluminum, cast malleable iron (aka pot metal), cast zinc (aka thin wall), fabricated steel, and machined steel from bar or tubing. Because all listed fittings meet minimum performance criteria, the Code doesn’t specify what type of material you should use for those fittings. Therefore, you must base your decision on design considerations or personal preference.

UL Test for Meeting UL’s Mininum Requirements, NOT Your Design Requirements

While the original purpose of a metallic raceway was the protection of wires from mechanical damage, the metallic raceways of today serve a second purpose. Today, we expect them to carry fault currents — which are potentially lethal. That means we must pay special attention to component selection, preparation, and assembly. Whether you are installing electrical mechanical tubing (EMT), intermediate metal conduit (IMC) or galvanized rigid metal conduit (GRC), Sec. 110-3 of the NEC requires you to list and label your components.
Material composition is important, for example, when burying the conduit. In certain soils, you should use solid steel fittings or possibly less reliant cast malleable iron. In others, cast aluminum works best. If you’re going to bury conduit, find out what is customary for the locale. Your local distributor will know which material most installers use and may stock only fittings of that material. If you have any doubts, contact one of the manufacturers with the particulars of your application and get an engineering recommendation. Other factors to consider include local cathodic protection (which may either prohibit or require the use of aluminum in that facility’s soil), the appearance of the conduit, the availability of all fittings in the same material, and customer specifications.

DIE CASAT FITTINGS CHARACTERISTICS

 

Image result for emt conduit run

EMT STEEL FITTINGS CHARACTERISTICS

 

For practical purposes, a conduit is open to the environment unless you use special families of fittings. For wet locations, use fittings listed for that use. Fittings listed as raintight may require a separate sealing ring and a special assembly. However, raintight does not mean waterproof. For prolonged submersion in water, use NEMA 6 or 6P fittings. You should also use these in wet industrial environments, which include places heavy with coolants or machine oils — especially if those substances are present as aerosols or sprays
What about concrete-tight fittings? UL does list some fittings specifically for this application. Neither threaded fittings nor gland fittings require a specific listing or marking for this purpose. If you adequately tape (per the manufacturer’s recommendations) threadless GRC/IMC fittings, they pass the requirement for being concrete-tight. Don’t assume a concrete-tight fitting is watertight or raintight — those require specific listings. However, fittings listed as raintight automatically qualify as concrete-tight.
Although many of us associate unthreaded metallic raceway with EMT, we also work with unthreaded conduit. Thus, unthreaded fittings are available for conduit. The unthreaded fittings fall into two general categories: gland (compression) type and set screw type. Gland type is the only type of unthreaded fittings listed for use in wet locations. Use only one type of fitting for a job. Otherwise, electricians will have to play mix-and-match games that slow down the work and increase the cost of labor. Let’s look at the kinds of fittings available for both threaded and unthreaded conduit systems.
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