AFCIs: Do Homes Need More?

Filed in Codes and Regulations by on December 21, 2017 1 Comment

plugExpanded requirements for arc fault circuit interrupters (AFCI) are on the docket for discussions that begin Jan. 8 on proposals to amend the National Electrical Code in its next edition, which will be published in 2020.

AFCIs are designed to limit the number of electrical fires by detecting certain kinds of arcing events. However, new research by the NAHB Construction, Codes and Standards staff indicates that there is not enough data to demonstrate that they are effective.

The 2008 edition of the code expanded the mandate from just bedrooms, which had been required since 2002, to include family rooms, dining and living rooms, libraries, recreation rooms, closets and hallways.

The 2014 edition added AFCI requirements for kitchens and laundries. Only bathrooms, unfinished basements, garages and outdoors outlets are not required to have AFCI protection.

“We often hear that adding more AFCI coverage to dwellings ‘just makes sense’ based on the information presented in the 1990s leading to the initial 2002 mandate,” said senior program manager Dan Buuck in a letter to fellow members of the panel considering the amendments.

“We are also asked to trust that AFCI technology is effective in protecting against certain arcing events, but we don’t have the data to back that up. In fact, it hasn’t lived up to expectations,” he said.

If added to all circuits, AFCIs would constitute over $500 of the cost for the average home. According to the Census Bureau’s Survey of Construction, 738,000 single-family homes were completed in 2016. “That’s a total of over $369 million annually if all those new homes had to meet that requirement,” Buuck said.

Meanwhile, other changes have made significant improvements in home safety by reducing the chances that an electrical fire will occur.

For example, the National Electrical Code requires electrical wires not to run less than 1 1/4 inches from the front edge of the framing members or be protected with a steel plate or other means. This almost eliminates the chance of wires getting hit by nails or screws because it offers a margin of safety against such damage. Standard nails and screws for 1/2-inch drywall are 1 1/4 inches long, leaving a half inch of space between the fastener and where a wire might run.

Provisions also include requiring wires to be supported at a maximum spacing of 4 1/2 feet, a maximum 12 inches from an electrical box to reduce vibrations causing the wire to rub where it enters the box, and requiring bushings where wiring runs through openings in metal framing members and where entering an electrical box or fitting.

Going forward, AFCIs might even become less effective, Buuck said. AFCI devices listed to the standard need to pass a test in which they trip when a prepared conductor arcs and before surgical cotton wrapped around the conductor ignites.

“In the latest development cycle, a manufacturer proposed changing the protocol to allow a test to be considered indeterminate and repeated if sparks ejected from the conductor ignite the cotton after they bounce off the tester apparatus. The change wasn’t approved by the committee, but it highlights the direction the manufacturers would like to see the standard go. This also enforces what we know, that a branch circuit protected by an AFCI device can still be subject to arcing,” Buuck said.

In light of the code improvements and the scant data regarding their effectiveness, a better approach may be to scale back AFCI requirements, he suggested.

For additional information, contact Dan Buuck at 202-266-8366.


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  1. AFCI technology, while it has been around since 2002, is still not ready to be installed in homes. They simply do not work, and we have taken out and replaced most of the AFCI circuit breakers we ever installed with conventional circuit breakers. The problem is that certain very common household loads, such as simple electro-magnitic alarm clocks will trip them every time. It is simply unacceptable to have your power go out every morning at 6:00 AM. Vacuum cleaners are another example of equipment that regularly trips AFCI breakers. Instead of trying to deal with equipment that will trip when we have an arc problem in the wall, we should change the way connections are put together to avoid the arc in the first place. Fix the problem, do not just create more problems!

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