EMT Conduits

[Wendell Swedberg]

.......

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[Jerry Peck]

Yes ... and ... no.

From the 2008 NEC. (bold is mine)
- 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 permanent 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.) 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 anywhere 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.

- 300.6 Protection Against Corrosion and Deterioration.
- - Raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware shall be of materials suitable for the environment in which they are to be installed.

If it rusts out: a) from 358.10 Uses Permitted - was it "protected by corrosion protection ... suitable for the condition"; or, b) from 300.6 Protection Against Corrosion and Deterioration - was it a material which met "shall be of materials suitable for the environment in which they are to be installed"?

Thus, Yes - if it does not rust out, and, No - if if does rust out.