Ecmweb 4655 Cw1nov10web
Ecmweb 4655 Cw1nov10web
Ecmweb 4655 Cw1nov10web
Ecmweb 4655 Cw1nov10web
Ecmweb 4655 Cw1nov10web

Whats Wrong Here?

Nov. 11, 2010
Hint: Corrosion control

How well do you know the Code? Think you can spot violations the original installer either ignored or couldn't identify? Here's your chance to moonlight as an electrical inspector and second-guess someone else's work from the safety of your living room or office. Joe, who has a knack for finding shoddy electrical work, did the dirty work and found this mess. Now it's your turn to identify the violation.

Find the Answer

This ¾-in. rigid metal conduit (RMC) shows a severe case of corrosion. Although it was properly installed long ago under an overpass along a major roadway, it has been subjected to many salt baths during the winter months when the roadway above is treated with sand and salt to prevent icing. So the question arises, "Should the designer or installer have done anything differently in anticipation of this future problem?"

Here are three specific Code sections we can reference that should apply to this type of installation.

  1. As noted in 110.11, "Unless identified for use in the operating environment, no conductors or equipment can be located in damp or wet locations; where exposed to gases, fumes, vapors, liquids, or other agents that have a deteriorating effect on the conductors or equipment; or where exposed to excessive temperatures."
  2. Section 110.12(B) covers the integrity of electrical equipment and connections. More specifically it states, "Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces, must not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, abrasives, or corrosive residues." The rule goes on to state that "no damaged parts may adversely affect safe operation or mechanical strength of the equipment." One can clearly see in the photo that the mechanical strength of this RMC has definitely been compromised over the years.
  3. Section 300.6 also covers protection against corrosion and deterioration. "Raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware must be of materials suitable for the environment in which they are to be installed." In addition, this statement appears in 300.6(A), "Where corrosion protection is necessary and the conduit is threaded in the field, the threads shall be coated with an approved electrically conductive, corrosion resistant compound."

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About the Author

Joe Tedesco

Tedesco served the industry in many roles during his career. He was a director, senior electrical code instructor for National Technology Transfer, Inc. and American Trainco, Inc.. He was also a codes, standards and seminar specialist for the International Association of Electrical Inspectors and an electrical field service specialist for the National Fire Protection Association in Quincy, Mass. He ran his own business as an NEC consultant and is a Massachusetts licensed master electrician and journeyman electrician and certified electrical inspector (one and two family 2A; General 2B, and Plan Review, 2C). Tedesco also wrote articles for CEE News and EC&M (Code Violations Illustrated and What's Wrong Here?) for more than 15 years and helped launched the Moving Violations video series.

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