Ecmweb 5136 Augustcodewatchwwh1web
Ecmweb 5136 Augustcodewatchwwh1web
Ecmweb 5136 Augustcodewatchwwh1web
Ecmweb 5136 Augustcodewatchwwh1web
Ecmweb 5136 Augustcodewatchwwh1web

What’s Wrong Here? Hint: Too Close for Comfort

Aug. 9, 2012
Can you identify the Code violation(s) in this photo?

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. It's your turn to identify the violation.

Hint: Too close for comfort

Find the Answer

It was a really close call for the roofers who installed those long deck screws. In fact, it may be unseen from this view, but it's possible that some screws may have penetrated directly into the back of either box. Installation requirements in 300.4(E) of the 2011 NEC address this type of situation.

A cable, raceway, or box, installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so there is not less than 38 mm (1½ in.) measured from the lowest surface of the roof decking to the top of the cable, raceway, or box. A cable, raceway, or box shall not be installed in concealed locations in metal-corrugated, sheet decking–type roof."

The use of the long screws by the roofers when making repairs to the roof is the exact reason why boxes and wiring must be spaced down 1½ in. from the roof deck. The self-tapping type screws used here could have easily damaged the wiring in the EMT or boxes.

Although the exception in this section of the Code allows rigid metal conduit (RMC) or intermediate metal conduit (IMC) to be installed without the required spacing, there is no exception for the boxes. Therefore, if RMC or IMC were used, the boxes would still need to be spaced down 1½ in. from the roof decking.

> Try Another Quiz

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.

Voice your opinion!

To join the conversation, and become an exclusive member of EC&M, create an account today!

Sponsored Recommendations

Electrical Conduit Comparison Chart

CHAMPION FIBERGLASS electrical conduit is a lightweight, durable option that provides lasting savings when compared to other materials. Compare electrical conduit types including...

Fiberglass Electrical Conduit Chemical Resistance Chart

This information is provided solely as a guide since it is impossible to anticipate all individual site conditions. For specific applications which are not covered in this guide...

Considerations for Direct Burial Conduit

Installation type plays a key role in the type of conduit selected for electrical systems in industrial construction projects. Above ground, below ground, direct buried, encased...

How to Calculate Labor Costs

Most important to accurately estimating labor costs is knowing the approximate hours required for project completion. Learn how to calculate electrical labor cost.