Fight Fires Before They Start

Any home fire is bad news, but it’s particularly troublesome when it’s caused by faulty wiring that could have been prevented.

Each year, nearly $650 million in property damage is caused from electrical fires, according to State Farm Insurance. One common cause of electrical fires is what’s known as a wiring arc fault. This can be caused by broken wires, deteriorated insulation or even driving a nail into a wire—and they can be deadly.

Arc faults result when there is a gap between two conductors or a conductor to ground and the electrical current jumps between the conductors. If there is something flammable in the way, the result is a fire.

By the time a typical household fuse or circuit breaker opens a circuit to neutralize these conditions, it’s too late. So when researchers identified Arc Fault Circuit Interrupters (AFCIs) as a promising new technology to prevent these fires, there was no happier group than electrical contractors.

Faulty Launch
The National Electrical Code (NEC) has required installation of AFCIs in 125V circuits used in bedrooms in new construction since 2002. Most municipalities in all but one state ( Wisconsin) have adopted the provision.

While the technology is promising, it hasn’t been fool-proof. In particular, electrical contractors complained about nuisance tripping with first-generation AFCIs.

“We had to install new AFCIs four times before they worked right,” says Joseph Sterbling, owner of Farmington Hills, Mich.-based Adler Building Co. “There was no reason in the world for them to trip. It was all new wiring with separate circuits. There’re going to have to get the bugs out.”

The Consumer Product Safety Commission (CPSC) and the National Association of State Fire Marshals, both say that AFCI technology is getting better.

“The effectiveness of AFCIs has continued to improve,” says Scott Wolfson, CPSC spokesperson. “The initial product had false tripping, but for the most part that problem’s been fixed. Now the problem is that most electricians just aren’t as familiar with the product as they need to be.”

Follow Instructions
Schneider Electric, manufacturers of Square D and Homeline AFCIs, analyzed the complaint calls it received during the first year of sales, as well as the follow-up solutions. Here’s what they found:

• 75 percent of the perceived problems with excessive tripping were ultimately attributed to bad wiring—exactly the problem AFCIs were created to identify, says Kenneth W. Breher, staff marketing specialist and professional engineer for Schneider.
• 11 percent were improperly installed—contractors didn’t follow the directions on the package.
• 4 percent were caused by faulty appliances plugged into the circuits, another problem that AFCIs were made to detect.

“We’ve found that the AFCIs require a little more discipline when they are installed because they will show up as problem wiring areas,” Breher says. “The contractor needed to learn new procedures when the GFI was introduced. Now he has to apply those procedures and more with installation of AFCIs.”

Schneider recommends these four steps for getting to the root of a tripping problem.

1. Start by looking for visible arching, the smell of smoke and buzzing noises.
2. Unplug all appliance and extension cords connected in the circuit. With the circuit de-energized, examine connections to the AFCI, receptacles, lighting fixtures and other appliances. If tripping continues when the AFCI is turned on, the fault is in the fixed wiring
3. Similarly, turn off all fixed appliances that have switches, such as lights and ceiling fans. Since these circuits can’t be fully disconnected (line, neutral and ground), tripping that occurs when their switches are turned off doesn’t necessarily mean that they’re fault-free.
4. If the AFCI doesn’t trip when all plugs are disconnected, turn on the AFCI again and reconnect the plugs one at a time. Then turn on fixed lights and appliances one at a time.

Because arcs are sometimes sporadic, turning off the circuit may temporarily clear the arc and it may not immediately reappear when the circuit is re-energized. If you unplug and reconnect appliances but still can’t locate the arc, turn off the main disconnect and use an ohmmeter to check for electrical continuity line-to-neutral, line-to-ground, and neutral-to-ground. If the insulation appears adequate, there may be a broken conductor or a loose connection.