ICC Provides Answers

Bob Sisson, Inspections by Bob, Boyds, Md., recommends using the International Code Council (ICC) as a resource, and provides the following example of how ICC helped him.

The ASHI Certified Inspector was questioned by a builder about the improper bundling of wires he reported during a pre-drywall inspection. Because he is an ICC member, he was able to request an interpretation.

Sisson said, “I sent two pictures [see below] and asked for an interpretation surrounding the bundling of the cables.

I was able to forward the reply from ICC to the builder, with the clout of the ICC behind the interpretation.
“I was impressed with the turnaround time on the interpretation,” he added … “I submitted a request verbally Friday night and got a call Monday morning.  A quick e-mail exchange and I had my interpretation.  It doesn’t get much better than that. Bravo, ICC.”
Here’s his message and the reply.

The question is about BUNDLING of wires in an insulated stud cavity. The wires will be surrounded with Fiberglas insulation inside the closed cavity.

Situation: Residential single-family new construction
The electrical panel is in the basement. All the wires for the second floor go up through the outside wall cavity of the first floor. In one “bundle” of wires, there are approx-imately nine wires, 4-15A circuits, 4-20A circuits and 1-30A circuit in the wall cavity secured in three places in the 8′. These wires will be surrounded with Fiberglas insulation.

I was trained (forever ago) that you couldn’t “bundle” more than three wires for more than 18″ without derating the wires …  this situation fails both conditions.I cannot find this in my 2002 NEC or 2003 IRC. Is it still there, and where would I find it? Is it still in later codes?
Lastly, if it is there, where is it and what is the “formal” wording?

Obviously, my concern is that this bundle will get hot, as there will be no (or should not be) any air circulating around this bundle once the cavity is stuffed with  Fiberglas.

The reply
Sections 3601.3, E3605.3 and E3605.4.4 and row one of Table E3702.1 of the 2006 IRC and section 334.80 of the 2008 NEC are the relevant sections. Note that the 2008 NEC has added a new rule about NM cables in thermal insulation, so your concern with insulation is valid now. The installation in the pictures lacks protection from physical damage and needs to be derated for conductor proximity because of the bundling and the thermal insulation, and possibly because of the number of cables that pass through a single bored hole in the wall plates. Note that section E3601.3 may or may not apply. See 2008 NEC section 334.80, which now clarifies the application of the 10%/10 foot rule. In summary, I see multiple violations in your pictures.

Learn more about ICC at www.iccsafe.org.

Everybody’s Building Code by Bruce A. Barker, ASHI Certified Inspector

This book empowers home inspectors and others who want to understand the International Residential Code without wading through the dry and often confusing language of the code itself.

Everybody’s Building Code states code requirements in direct, command-oriented statements and provides examples, illustrations and photographs that demonstrate how to apply the code requirements.

Finding all relevant IRC provisions often is a challenge. This book contains an extensive key-word index and a detailed Table of Contents that helps readers find the code provisions they need.

In cases where the code requirements may not reflect current best practices, the book discusses some opinions on the subject and directs the reader to other sources for more information.

Bruce A. Barker is president of Dream Home Consultants, LLC., a Phoenix, Arizona-based building inspection and consulting firm. During more than 21 years in the construction and building inspection industry, he has built more than 100 custom homes and inspected more than 1,000 houses. The author is certified by the International Code Council as a Residential Combination Inspector, is a licensed contractor in Arizona and Florida, and is certified as an infrared thermographer.

To read excerpts and to order the book, visit www.everybodysbuildingcode.com. The book also can be purchased on www.amazon.com.