Issue 77, November 23, 2002

Personal Note & Credits:

November 8th and 9th was spent in Charlotte at the North Carolina ASHI Fall Conference "Inspection Science 2003." One session of our continuing education was presented by Hal David Howard, Sr. Sales Engineer for Eaton Cutler-Hammer manufacture of electrical components. This information is mostly from his presentation titled "AFCI - Residential Electrical Trends." 

Arc Fault Circuit Interrupter
(AFCI)
"The latest in residential and commercial electrical safety technology"

You should be familiar with Ground Fault Circuit Interrupters (GFCI's) they are not the same as Arc Fault Circuit Interrupters (AFCI's). If you can't place what a GFCI is, it is the outlet or breaker with the little "Test" and "Reset" Buttons that trip when you are attempting to dry your hair, make waffles or use a circular saw. GFCI's are about protecting you from injury. AFCI's are different, they are about protecting your home from fire. AFCI's are now (as of January 1st 2002 in NC) required on all bedroom outlet circuits in new construction. You will find them as breakers in the electrical distribution panel on new homes where the construction permit was purchased this year. In this article I will deal with several issues related to AFCI's including: why we now have them, what they are, what they do, why they are only on bedroom circuits, how in the future they may be on all 125 volt circuits in homes and what to do if an AFCI breaker trips. 

Why Arc Fault Circuit Interrupters?

To understand the reason for AFCI's you must look at 1999 U. S. Fire Statistics:

1.8 million fires were reported

Direct property loss due to fires was estimated at $10 billion (that's BILLION!)

13.1 fire deaths per million population ranks the U.S. among the highest in the industrial world

3,570 deaths and another 21,875 injuries were the result of fire.

112 firefighters were killed in duty-related incidents.

There were 1,823,000 fires in the United States. Of these:

43% were Outside Fires
29% were Structure Fires
20% were Vehicle Fires
8% were fires of other types

Residential fires represented 21 percent of all fires and 73 percent of structure fires.

82 percent of all fatalities occurred in the home. Of those, approximately 81 percent occurred in single-family homes and duplexes.

Annually there are over 40,000 electrical fires, 350 deaths, 1700 injuries with $700 million in property losses. Unlike other causes (smoking, cooking fires and arson), electrical fires are less likely to be reduced by educational programs. A "technology solution" is the best chance of reducing residential electrical fires. 

Over 1.4 million new homes are built per year. There are over 100 million existing homes in the U.S. and thousands are remodeled each year. The potential for losses due to residential fires increases every year. 

Step in the government with a drive for a solution to the problem. The government challenged the electrical industry to provide new technology for detecting and monitoring conditions that could cause electrical wiring system fires. The conclusion was that electrical arc is a major cause of electrical system fires and that the most promising technology to deal with the issue is: Arc-fault detection and mitigation.

What is an "Arc-fault"? An arc is a plasma flame with associated temperatures in excess of 6000 degrees Celsius. Arcing Faults occur when insulation damage or loose connections allow a gap between two conductors or a conductor to ground. This gap can allow current to "jump" between conductors.

It has been observed that 72% of electrical fires start in cords leading to and in appliances and in light fixtures and their associated wiring. Some of the most common causes of electrical fires are:

Improperly installed wall plugs or switches or where their connection become loose over time.

Cords that get caught in door jambs.

A nail from a picture hanger breaks the insulation on a wire inside of the wall.

Damaged, abused or worn extension cords.

Furniture pushed against a cord plug at the outlet.

A standard breaker or GFCI does not protect against these conditions. 

Some arch faults are detectable as lights and appliances which operate intermittently. The ones you will be the most familiar with is the hair dryer or vacuum cleaner cord which is broken. It stops because there is a broken wire and runs intermittently from an arch fault. Have you ever been startled when the fire flies or burned by a hot spot? These are series arc's. Unfortunately all arch faults are not as obvious. This gets a little more technical, but you can experience a "parallel arc" which is an arc from line to line or line to neutral in parallel with a connected load. This arcing fault may not "announce" itself, the available fault current is not limited by the load, it is capable of sputtering for long periods of time and can go unnoticed until fire starts. 

After reading all of this, don't you think it would be great if there was a method of detecting this problem and stopping if from burning your home down and possible taking you and your children along with it? Well, our government and the electrical industry thinks so as well. Out of all of this came the "Arc Fault Circuit Interrupter." 

What an Arch Fault Circuit Interrupter is and Where it is Required

Eaton Corporations Cuttler-Hammer Division (from whom most of the data in this article was derived) calls theirs FIRE-GUARD Arch Fault Circuit Interrupters. "The latest in residential and commercial electrical safety technology." For a definition and as to where they are now required we look at the 1999 and 2000 National Electrical Code:

"Section 210-12(a) Definition - An arc-fault circuit interrupter is a device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc is detected."

"Section 210-12(b) Dwelling Unit Bedrooms - All branch circuits that supply 125 volt, single phase, 15 and 20 ampere receptacle outlets installed in dwelling unit bedrooms shall be protected by an Arc-Fault Circuit Interrupter(s)."

Revised December 2000: "All branch circuits that supply 125 volt, single phase, 15 and 20 ampere receptacle outlets in dwelling unit bedrooms shall be protected by an arc-fault circuit interrupter's listed for protection of the entire branch circuit. This requirement shall become effective January 1, 2002."

Why Not Before? Why Only in Bedrooms?

The reason this type protection has not been available before is that it was big, expensive and not reliable. The miniaturization of electrical circuitry and advances in technology has allowed for this break through. The reason that it is only required now on bedroom circuits is that when ground fault circuit protection was introduced many years age there were many frustrating problems with its reliability. This is a test on the least loaded circuits in our homes. We are being broken is over time as the industry improves the technology and reduces its related cost. The goal is more reliability and decreased cost which will result in these devices being required on all 125 volt circuits with the outcome being less fires and safer homes. 

What to do if an AFCI Breaker Trips:

When any circuit breaker trips it is good practice to locate the source of the fault and correct the fault before resetting the breaker. Obvious signs of overloads (too many loads on the same circuit microwave, toaster, range, and lights for example) or short circuits such as damaged wires, blackened receptacles, etc., need to be addressed prior to attempting to reset the breaker. The person that is doing the investigation of the circuit should first determine what loads are connected to the circuit, which loads were on at the time of the trip, calculating the connected load to see if the cause was an overload. The next step would be to trace the circuit and thoroughly check all connections for damaged insulation burned receptacles and any other evidence of a short circuit. If you are unable to determine and correct the cause of the trip you should not reset the circuit, but should call a licensed electrician to inspect the system. If you are determined and brave and reset the breaker and it trips a second time without your determining and correcting the problem DON'T BE STUPID, CALL FOR HELP.

 Thought for the week
 
Just because you assume you home is safe doesn't mean that it is.