Tom Denniston installs an arc fault circuit interrupter in an Ida Township, Michigan, home.
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Sleeping in Michigan just got a little safer, at least for people with new homes.
That's because the revised 2004 Michigan Building Code requires the installation of new, more protective electrical circuits for bedrooms. Such arc fault circuit interrupters have been required in Ohio for about a year.
Both states require them in newly built houses and remodels or wiring upgrades in existing homes.
The devices, also known as AFCIs, detect arcing and sparking of electrical wires, which account for 85 percent of all electrical faults, according to the National Fire Prevention Association.
The trade group said 389,000 home fires were reported in the United States in 2002, resulting in 2,670 deaths, 13,650 injuries, and $5.9 billion in direct property damage.
Only one-fifth of home fires occurred between 10 p.m. and 6 a.m., but almost half of fire deaths in 1999 stemmed from blazes that broke out during that time frame.
The arc interrupters are different from ground fault circuit interrupters, which are commonly found in kitchens, bathrooms, and garages. The ground fault interrupters work only on individual electrical outlets. When an electric problem occurs while an outlet is in use, the circuit interrupter cuts power to that outlet.
The arc interrupters, however, work from the circuit box on wiring throughout a given room or rooms. So if a wire is frayed in a wall or even on a plugged-in extension cord, the device will detect an "arc" of electric current and shut down power to that area so a fire doesn't start. The arc interrupter works even if no electricity is being drawn from an outlet.
A traditional fuse or circuit breaker also would respond to such sparking, but over a longer span of time, and that could allow for smoldering or flames.
"[The arc interrupters] are only in bedrooms right now because that's where you need the most protection when you're not awake," said John Walters, Lucas County building inspector.
"It's just an opinion of mine, but I see this requirement spreading to other rooms because it's a good concept."
Electrical problems that could be prevented by arc protection can occur in any room of a house, but a fire starting in the bedroom gives the occupants perhaps less time to escape than one in another room that might trigger a smoke alarm.
Such arcs can occur at loose connections or where wires or cords have been damaged or when rodents have chewed on the wiring.
Another concern, said Mr. Walters, is if a carpenter or another worker nicks a wire inside a wall while driving a nail.
"You'd never know, but that would tend to build up heat and start a fire," said Mr. Walters. "This will actually sense there's something wrong in that circuit and shut it down."
Tom Susor, operations manager for TAS Inc. in East Toledo, said his company has installed the arc interrupters for several months.
"If you've got a bed against the wall and a nearby air conditioner is plugged in and the cord is loose and it starts to spark, it [the interrupter] senses that and trips the breaker, protecting you from a fire," Mr. Susor said.
Individual arc interrupters cost about $35.
The arc system requires added wiring so that each room is on a separate circuit, rather than several rooms being on a circuit, as is common today.
That added wiring, electricians estimate, would cost about $50 a room or $300 to $400 for an entire house.
The National Electric Code of 1999 required the arc interrupters be put on all 15-amp and 20-amp bedroom circuits in new construction starting in 2002, a rule that was restated in the National Electric Code of 2002.
But questions and confusion about the code meant later start dates in some states, such as Ohio and Michigan.
A ground fault circuit interrupter costs $35, the same price as the new arc interrupters, but there are now electric outlet products available for $10 to $12 that allow a homeowner to test and reset the circuit right in the bathroom, for example.
Such a product is not yet available for the arc interrupters, said Phil Carlson, counter and warehouse manager for Mick Electric Inc. in Toledo.
Mary-Beth McLaughlin at firstname.lastname@example.org or 419-724-6199.