I. General
under the fill.
(4) In any hazardous (classified) location except as permitted by other articles in this Code.
(5) For the support of luminaires or other equipment except conduit bodies no larger than the largest trade size of the tubing.
(6) Where practicable, dissimilar metals in contact any- where in the system shall be avoided to eliminate the possibility of galvanic action.
Exception: Aluminum fittings and enclosures shall be permitted to be used with steel EMT where not subject to severe corrosive influences.
358.1 Scope. This article covers the use, installation,
and construction specifications for electrical metallic
tubing (EMT) and associated fittings.
358.2 Definition.
Electrical 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. EMT is generally made of steel (ferrous) with protective coatings or aluminum (nonferrous).
358.6 Listing Requirements. EMT, factory elbows, and associated fittings shall be listed.
II. Installation 358.10
Uses Permitted.
(A) Exposed and Concealed. The use of EMT shall be permitted for both exposed and concealed work.
(B) Corrosion Protection. Ferrous or nonferrous EMT, elbows, couplings, and fittings shall be permitted to be installed in concrete, in direct contact with the earth, or in areas subject to severe corrosive influences where protected by corrosion protection and judged suitable for the condition.
(C) Wet Locations. All supports, bolts, straps, screws, and so forth shall be of corrosion-resistant materials or protected against corrosion by corrosion-resistant materials.
FPN: See 300.6 for protection against corrosion.
358.12 Uses Not Permitted. EMT shall not be used under the following conditions:
(1) Where, during installation or afterward, it will be subject to severe physical damage.
(2) Where protected from corrosion solely by enamel.
(3) In cinder concrete or cinder fill where subject to per- manent moisture unless protected on all sides by a layer of noncinder concrete at least 50 mm (2 in.) thick or unless the tubing is at least 450 mm (18 in.)
358.20 Size.
(A) Minimum. EMT smaller than metric designator 16 (trade size Vz) shall not be used.
Exception: For enclosing the leads of motors as permitted in 430.245(B).
(B) Maximum. The maximum size of EMT shall be met- ric designator 103 (trade size 4).
FPN: See 300.1(C) for the metric designators and trade sizes. These are for identification purposes only and do not relate to actual dimensions.
358.22 Number of Conductors. The number of conduc- tors shall not exceed that permitted by the percentage fill specified in Table 1, Chapter 9.
Cables shall be permitted to be installed where such use is not prohibited by the respective cable articles. The number of cables shall not exceed the allowable percentage fill specified in Table 1, Chapter 9.