What is the difference between a Combination Type AFCI and a Branch/Feeder AFCI?
The Siemens Combination Type AFCI provides protection against all three types of arcs (series, line-to-neutral, and line-to-ground). The Combination Type meets all the 1999 and later NEC® requirements. It is specifically required by the 2005 NEC® beginning January 1, 2008.
The Siemens Branch/Feeder AFCI provides protection against two types of arcs (line-to-neutral and line-to-ground). It can be used to meet the requirements of the 1999-2002 NEC® and the 2005 NEC® until January 1, 2008.
Why is arc detection needed?
Arcing faults generally go undetected for an extended time and can reach high temperatures even at low current levels. These temperatures can easily exceed the combustion point of common building materials.
According to the Consumer Product Safety Commission, problems in home wiring, like arcing and sparking, are associated with more than 40,000 home fires each year. These fires claim over 350 lives and injure 1,400 victims annually. And while standard circuit breakers are intended to protect conductors from overload and short circuit conditions, they do not protect against arcing faults and ground faults.
How is an AFCI different from a GFCI?
Although the AFCI and GFCI may look very similar, their purpose is quite different. AFCIs are designed to address the hazards that result from arcing, while GFCIs (Ground Fault Circuit Interrupters) are designed to address shock hazards and are intended for the protection of personnel.
Would you wire an AFCI circuit breaker differently than a GFCI circuit breaker?
No. Similar to a GFCI, you connect the neutral (pig-tail) wire to the load center neutral bar. The load wire goes to the terminal marked "LOAD POWER" and the load neutral wire goes to the terminal marked "LOAD NEUTRAL."
Can you use an AFCI on a two wire system with no equipment ground?
Yes, an AFCI does not require an equipment ground to perform its intended function. A retrofit into a home with a two wire system is an acceptable application for an AFCI. In fact, Siemens encourages the use of AFCIs in these homes as aged wiring systems also present the potential for arcing.
Does the term “Combination” mean that GFCI protection is included?
No, it only means that the device protects against all three types of arcing. Any device that would include GFCI protection would be referred to as a dual function device.
What about nuisance tripping?
Siemens AFCI circuit breakers are designed to resist nuisance tripping when wired to a variety of loads found in the home, while keeping their full sensitivity to detect arcs. AFCIs have been tested with a wide variety of products including fluorescent lights, hand drills, welders, hairdryers, dimmers, and other appliances containing electric motors to ensure that they will not nuisance trip and to ensure that these loads would not mask the presence of an arc.
How do I test to determine if my AFCI circuit breaker is functioning properly?
To test an AFCI, make sure there is power to the load center, or panelboard. Turn the AFCI handle to the "ON" position. Press the blue test button. Pressing the test button simulates an arc to the AFCI sensing electronics, causing the breaker to trip. The AFCI breaker is functioning properly when the circuit is interrupted and the handle moves to the tripped center position. To reset, turn the AFCI off and turn it on again. If the AFCI does not trip when the test button is pressed, it should be replaced. Refer to a qualified electrician for servicing. You should test your AFCI breaker monthly to insure protection against electrical arcing faults.
Is there a hand-held device that can test an AFCI circuit breaker?
At the present time, Siemens is not aware of a separate unit which can completely test the operation and functionality of an AFCI circuit breaker. If you do see an AFCI hand-held tester on the market, it is advisable to carefully read the manufacturer's packaging. UL has warned of potentially hazardous AFCI circuit testers out in the market.
The Push-to-Test button is always an acceptable test for the AFCI circuit breaker, whether Combination Type or Branch/Feeder.
Can you use a hand-held GFCI tester to test an AFCI circuit breaker?
No. While some GFCI testers may cause an AFCI to trip, these devices are not testing the arc detection capability of the breaker. AFCIs utilize a differential sensor to detect leakage of current in a circuit. When the GFCI tester creates a leakage of current greater than the threshold level of the AFCI's differential sensor, the device will open. However, this fault detection is not intended to provide personnel protection, as the AFCI trip thresholds for differential current vary by manufacturer but are typically 30mA to 60mA – far above the 5mA level required for personnel protection. In addition, AFCIs do not specifically include grounded neutral protection.
Could an AFCI feel warmer than other breakers in the same panel?
An AFCI breaker may feel warmer to the touch than a non-AFCI circuit breaker. This is due to the heat generated from the power supply for the electronics. Siemens AFCI breakers tested in an average ambient temperature of 23° C (73° F) operated at an average temperature of 38° C (100° F.) This is well within the UL Standard 489 Section 7.1.4.1.3 which states - Temperature rises on handles, knobs, and other surfaces subject to user contact during normal operation shall not exceed 60°C (140°F) on nonmetallic surfaces. It is warm enough to detect with the hand, but this heat does not impact the operation of the AFCI.
