Ecmweb 6350 Nec Illustrated Catastrophes May 2014 Pr
Ecmweb 6350 Nec Illustrated Catastrophes May 2014 Pr
Ecmweb 6350 Nec Illustrated Catastrophes May 2014 Pr
Ecmweb 6350 Nec Illustrated Catastrophes May 2014 Pr
Ecmweb 6350 Nec Illustrated Catastrophes May 2014 Pr

Illustrated Catastrophes: EMT Errors and Box Violations

May 20, 2014
More Code catastrophes uncovered and corrected in these faulty installations

All references are based on the 2014 edition of the NEC.

Hitchin’ a Ride

Believe it or not, buried deep in this bundle is a piece of ¾-in. electrical metallic tubing (EMT). Unfortunately, all of the communication cables, raceways, and optical fiber cables that are secured to it obscure it from view. Not only are these cables and raceways putting extra strain on the clips that were designed to secure and support only one EMT, but they can also trap the heat generated by the current flow on the conductors inside the pipe. This trapped heat may cause the conductors to operate too hot, which can lead to insulation breakdown and eventual failure.

According to Sec. 300.11(B), raceways can only be used to support other raceways or cables where the raceway is “identified as a means of support,” or where the raceway contains power conductors for electrical equipment and is supporting Class 2 control circuits connected to the same piece of equipment. Raceways may also support boxes in accordance with Sec. 314.23, or luminaires in accordance with 410.36(E).

In this installation, the cables and raceways bundled to the EMT are simply hitching a ride along the way because the installer(s) took the easy way out, and did not take the time to properly support the additional wiring.

Pandora’s Box

So many problems — so little space to write about them… I’ll begin with the missing cover.

As required by Sec. 314.25, for completed installations, each box must have a cover, faceplate, lampholder, or luminaire installed to cover the opening and protect the wires in the box. The next problem is the equipment ground wire wrapped around the 8/32 screw that is intended to secure the box cover. This violates Sec. 250.148(C), which requires a grounding screw to be used for no purpose other than connecting the equipment grounding conductor to the metal box. The next violation is the lack of cable connectors for the two NM cables entering the top corner of the box. Section 314.17 requires these cables to be protected from abrasion as they enter the box, and the openings should be closed in an approved manner. The next problem is the way in which the cables are installed on the floor of this attic space. Section 334.23 requires NM cables installed in an accessible attic to comply with the rules of Sec. 320.23. Where cables are installed within 7 ft of the attic floor, they “shall be protected by guard strips,” which are at least as high as the cable. Lastly, using green grounding-type wire connectors for splicing the white and black wires violates the requirements of Sec. 110.3(B).

About the Author

Russ LeBlanc | Owner

Russ started in the electrical trade as an apprentice in 1985. He worked his way up to become a Journeyman Electrician and then eventually became a Master Electrician and Licensed Construction Supervisor. In 1999 Russ become an Electrical Instructor for The Peterson School of Engineering in Massachusetts where he developed his passion for teaching, and quickly became Department Head of Electrical Instruction. Russ has taught thousands of apprentices, electricians, engineers, inspectors, and other electrical professionals during his career as an instructor. He continues to provide electrical professionals with Electrical Code seminars, Arc-Flash Awareness training seminars and educational material through his LeBlanc Consulting Services in North Reading, MA whose specialty is educating electricians. He has been an active member of the NFPA Electrical Section and has authored hundreds of National Electrical Code proposals and comments which have become Code rules to improve the safety for the electrical industry. Russ is also an IAEI certified Electrical Inspector.

Please visit www.russleblanc.net for more information.

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