Basics of AFCI Circuit Breakers - SITRAIN LMS · 2018. 3. 7. · GFCI protection in the home is...

Basics of AFCI Circuit BreakersA quickSTEP Online Course

www.usa.siemens.com/step© Siemens industry, Inc.

© Siemens Industry, Inc. 2017

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Siemens is a trademark of Siemens AG. Product names mentioned may be trademarks or registered trademarks of their respective companies.

National Electrical Code® and NEC® and NFPA 70® are registered trademarks of the National Fire Protection Association.

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Other trademarks are the property of their respective owners.

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Course Topics

Welcome to Basics of AFCI Circuit Breakers. This course covers the following topics:

• Introduction• AFCI Circuit Breakers• Intelli-ARC Diagnostic Tool• Final Exam

If you do not have an understanding of basic electrical concepts, you should complete Basics of Electricity before attempting this course.

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Course Objectives

Upon completion of this course you will be able to…• Define the term arc fault.• Describe the potential danger of arc faults.• Identify the some common causes of arc faults in residential and light commercial

applications.• List the basic recommendations for reducing arc faults.• Differentiate an AFCI circuit breaker from a standard circuit breaker.• Differentiate an AFCI circuit breaker from a GFCI circuit breaker.• Briefly describe the evolution of the NEC® as it relates to AFCI circuit breaker use.• Differentiate a branch/feeder AFCI circuit breaker from a CAFCI circuit breaker.• List the residential AFCI circuit breaker types sold by Siemens.• Describe the diagnostic features built into Siemens AFCI circuit breakers.• Describe the basic features of Siemens Intelli-Arc Diagnostic Tool.• Briefly describe how an electrician uses Siemens Intelli-Arc Diagnostic Tool when

troubleshooting a branch circuit.

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SITRAIN® Training for Industry

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Simulators - World-class simulation systems available for training or purchase

This course also describes learning options available from the Siemens SITRAIN USA organization and our global SITRAIN partners. For additional information: www.usa.siemens.com/sitrain


Arc Faults

Arc faults are electrical arcs between or along conductors or from a conductor to ground. In residential and light commercial applications, these arc faults are not as dramatic as those that occur in large commercial and industrial applications where higher levels of voltage and current are present.

However, it is important to understand that despite the relatively low levels of energy typically associated arc faults in residential and light commercial applications, the danger associated with these faults is significant.

Every year in the U.S. alone tens of thousands of fires resulting in hundreds of deaths, over a thousand injuries, and a billion dollars or more in property damage are caused by electrical failure or malfunction. A significant percentage of these fires are caused by arc faults.

Because of this danger, it is critically important to detect arc faults and to interrupt the flow of current when they are detected. In that regard, this course focuses on arc fault circuit interrupter (AFCI) circuit breakers, with emphasis on Siemens products.

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Common Causes of Arc Faults

There are numerous causes of arc faults in residential and light commercial applications. The accompanying graphic shows a few common examples. With these examples in mind, there are some common sense recommendations to consider.

• Do not run power cords in areas where they can be damaged by doors, furniture, equipment, or foot traffic.

• Do not push furniture or equipment up against electrical plugs.• When unplugging an electrical cord, pull with your hand on the

plug rather than with your had on the cord.• If blackened plugs, damaged wires, or noisy circuit breakers

are discovered, contact a licensed electrician.• Take care when using drywall screws, nails, staples or similar

items to ensure that they do not damage electrical conductor insulation.

• When making minor electrical repairs, make sure that you familiarize yourself with good electrical practices.

• When more significant electrical repairs or other electrical work is required, contact a licensed electrician.

• If an arc fault circuit interrupter circuit breaker trips, check for defective power cords and make sure that all light bulbs on the circuit are fully screwed into their sockets. If no problems are found, and the circuit breaker trips again, contract a licensed electrician.

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AFCI Circuit Breakers

Like standard circuit breakers, AFCI circuit breakers are designed to open a circuit when an overload or short circuit is sensed. However, an arc fault typically will not generate enough fault current to trip a standard circuit breaker. Only an AFCI circuit breaker incorporates circuitry that continuously monitors voltage and current to arc faults. When it detects an arc fault, an AFCI circuit breaker opens the circuit, stopping the flow of current.

There are two categories of AFCI circuit breakers, branch/feeder AFCI circuit breakers and combination AFCI (CAFCI) circuit breakers.

Branch/feeder AFCI circuit breakers, in addition to providing overcurrent protection, are intended to protect branch and feeder wiring from the damaging effects of line-to-ground arcs and high energy parallel arcs. High energy parallel arcs are line-to-neutral arcs of at least 75 amps.

CAFCI circuit breakers, in addition to providing overcurrent protection, are intended to protect downstream wiring from three categories of arc faults: line-to-ground arcs, high energy parallel arcs of at least 75 amps, and series arcs of at least 5 amps. Series arcs are arcs on a single conductor.

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GFCI Circuit Breakers Versus AFCI Circuit Breakers

Because the term ground fault circuit interrupter (GFCI) is similar in wording to AFCI, it is easy to confuse the terms. The important thing to remember is that a GFCI is designed to interrupt current when it detects a ground fault, but it does not provide AFCI protection.

A ground fault occurs when current in a circuit flows to ground in an unintended way, often because of a breakdown in conductor insulation or contact with water. Because of the potential safety hazard that ground faults pose, the NEC® requires circuits in areas such as bathrooms, garages, outdoors, unfinished basements, and kitchens to have GFCI protection.

GFCI protection in the home is often accomplished by use of receptacles with a built-in GFCI. In some applications, however, it makes sense to use GFCI circuit breakers instead of GFCI receptacles. A GFCI circuit breaker, in addition to providing ground fault protection, also provides the same overcurrent protection as a standard circuit breaker. One additional thing to keep in mind is that the GFCI circuit breakers used in residential applications are designed to trip when a ground fault of 5 mA or greater is detected. There is another category of GFCI circuit breaker that is used in some commercial applications for equipment protection and requires a ground fault of at least 30 mA to trip.

As a result of the expansion of requirements for AFCI protection, some circuit breakers now provide both AFCI and GFCI protection.

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National Electrical Code®

NEC® Article 210.12 covers arc fault circuit interruption protection. As shown below, the requirements for AFCI protection have evolved. Because adoption of the NEC varies by state, review the version of the code adopted by your building authority for additional information.• 1999 NEC - Allows branch/feeder AFCIs beginning on January 1, 2002 for

bedroom receptacles.• 2002 NEC - Listed AFCI in all bedroom circuits – Allows branch/feeder AFCIs.• 2005 NEC - Combination Type AFCI in bedroom circuits. Branch/feeder AFCIs

permitted until January 1, 2008.• 2008 NEC - Expands use of combination AFCIs to 1-pole, 15-20 amp circuits

installed in bedrooms, family rooms, living rooms, parlors, libraries, dens, sun rooms, recreation rooms, closets or similar rooms.

• 2011 NEC - Combination AFCI required for 15-20 amp circuits installed in family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas.

• 2014 NEC - Combination AFCI or dual function AFCI/GFCI required for all 120 volt, single-phase, 15-20 amp branch circuits supplying outlets or devices installed in dwelling unit, kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas or similar rooms or areas.

• 2017 NEC - Combination Type AFCI or dual function AFCI/GFCI required for all 120 volt, single-phase, 15-20 amp branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas or similar rooms or areas. Page 1-10


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For the full course duration, you can complete assignments and reinforce classroom instruction using a virtual cloud-based application providing 24/7 access to fully functional Siemens software such as SIMATIC STEP 7 and PLCSIM.


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Basics of AFCI Circuit Breakers

This chapter covers the following topics:

• Introduction

• AFCI Circuit Breakers

• Intelli-ARC Diagnostic Tool

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Combination AFCI Circuit Breakersfor Load Centers

Siemens offers 1-pole and 2-pole QAF2 and QAFH2 combination AFCI (CAFCI) circuit breakers and 1-pole HQAF2 CAFCI circuit breakers. QAF2 circuit breakers have a 10 kA interrupting rating, QAFH2 circuit breakers have a 22 kA interrupting rating, and HQAF2 circuit breakers have a 65 kA interrupting rating.

All of these circuit breakers are available with 15 or 20 amp continuous current ratings. The 1-pole circuit breakers are rated for 120 VAC. The 2-pole circuit breakers are rated for 120/240 VAC, which means that they may be applied in a circuit where the nominal voltage between any conductor and ground does not exceed 120 VAC and the nominal voltage between conductors does not exceed 240 VAC.

Siemens CAFCI circuit breakers have a white pigtail wire that attaches to the neutral bus. 2-pole CAFCI circuit breakers have two Test buttons and all other Siemens CAFCI circuit breakers have one Test button. Test buttons are used to check the device operation after it has been installed.

As shown in the accompanying illustration, Siemens CAFCI circuit breakers are equipped with LED trip indicators, which help electricians and home owners identify the cause of a tripped breaker. Page 2-14


2-Pole Combination AFCI Circuit Breakers

Siemens 2-pole CAFCI circuit breakers are intended for a different use than most 2-pole circuit breakers. Instead of being used with one 240 VAC circuit, it is intended for use on two, 1-pole, 120 VAC circuits.

When using 1-pole CAFCI breakers, a dedicated neutral is required for each circuit, but a Siemens 2-pole CAFCI breaker allows electricians to use multi-wire branch circuits (commonly known as shared neutrals) between the two circuits fed by the breaker.

The biggest changes for electricians wiring multi-wire branch circuits are the number of conductors in the homerun cable and the home run connection. In a typical dedicated neutral circuit, electricians use a cable with two insulated conductors, color-coded for line and neutral, and a bare ground wire. In a multi-wire branch circuit, electricians use a cable with three insulated conductors color coded for the hot wires and the neutral wire, and a bare copper ground wire.

Using multi-wire branch circuits saves money through reduced wire usage. In addition, depending on wiring practices, installers could see a labor savings as well, because of fewer stud and floor penetrations and fewer cables to pull.

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Dual Function CAFCI/GFCI Circuit Breakersfor Load Centers

The most recent versions of the NEC® require both CAFCI and GFCI protection for some circuits. Previously, the only option to comply with this requirement was to pair an CAFCI circuit breaker with a GFCI receptacle. Siemens dual function CAFCI/GFCI circuit breakers combine these function in one device while also providing overload and short circuit protection.

Siemens QFGA2, QFGAH2, and HQFGA2 dual function circuit breakers are available for use as branch breakers in a variety of Siemens load centers. They are available with a 15 amp or 20 amp continuous current rating. Type QFGA2 circuit breakers have a 10 kA interrupting rating, type QFGAH2 circuit breakers have a 22 kA interrupting rating, and type HQFGA2 circuit breakers have a 65 kA interrupting rating.

These circuit breakers have a “self test” feature that enables the breaker to automatically and continuously test itself. If the test fails, the circuit breaker trips, and the LEDs blink. If the circuit breaker is reset and immediately trips again, contact an electrician to resolve the problem.

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Circuit Breakers for WireGuide Load Centers

Siemens WireGuide load centers accept CAFCI, GFCI, and dual function CAFCI/GFCI WireGuide circuit breakers. These circuit breakers come complete with a pre-trimmed neutral wire, eliminating installation steps. The neutral wire seamlessly slides into the neutral bar as the breaker is being installed allowing for a secured bolted connection. The neutral wire has an "Oops Loop" providing extra wire if needed in the event the wire is damaged during installation.

Siemens type QAF2 is a 1-pole CAFCI circuit breaker, type QAF is a 2-pole CAFCI circuit breaker, type QPF2 is a 1-pole GFCI circuit breaker, and type QFGA2 is a 1-pole dual function circuit breaker. These breakers are available with a continuous current rating of 15 amps or 20 amps.

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Combination AFCI Circuit Breakersfor Panelboards

The circuit breakers discussed thus far in this course are intended for use in Siemens load centers. Siemens also offers 1-pole and 2-pole CAFCI and 1-pole dual function CAFCI/GFCI circuit breakers for use in Siemens panelboards. Like other panelboard circuit breakers, these are bolt-on breakers.

These circuit breakers have similar functionality to the comparable breakers used in Siemens load centers. All of these circuit breakers are available with 15 or 20 amp continuous current ratings. The 1-pole circuit breakers are rated for 120 VAC. The 2-pole circuit breakers are rated for 120/240 VAC.

The following Siemens CAFCI circuit breakers are available. 1-pole BAF2 and 2-pole BAF circuit breakers have a 10 kA interrupting rating, 1-pole BAFH and 2-pole BAFH2 circuit breakers have a 22 kA interrupting rating, and 1-pole HBAF2 circuit breakers have a 65 kA interrupting rating.

The following Siemens dual function CAFCI/GFCI circuit breakers are available. 1-pole BFGA2 circuit breakers have a 10 kA interrupting rating, 1-pole BFGAH2 circuit breakers have a 22 kA interrupting rating, and 1-pole HBFGA2 circuit breakers have a 65 kA interrupting rating. Page 2-18


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Basics of AFCI Circuit Breakers

This chapter covers the following topics:

• Introduction

• AFCI Circuit Breakers

• Intelli-ARC Diagnostic Tool

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Intelli-Arc Diagnostic Tool

Arc faults are often intermittent, which can make troubleshooting branch circuits difficult. However, Siemens Intelli-Arc Diagnostic Tool helps to accurately diagnose the circuit in which a fault has occurred. This diagnostic tool can be used with any circuit breaker regardless of brand. When used in conjunction with good troubleshooting techniques, this tool allows an electrician to locate the cause of the fault more quickly, saving money for each branch circuit that must be evaluated.

The Intelli-Arc Diagnostic Tool provides a visual indication of the type and magnitude of a fault. Because the fault may not cause an AFCI to trip for various reasons, i.e., duration too short or current level too low, the tool provides an indication showing how close an event is to causing an AFCI to trip.

The Intelli-Arc Diagnostic Tool includes a base unit, which is temporarily wired into a branch circuit, and a hand-held unit, which wirelessly communicates with the base unit.

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Using the Intelli-Arc Diagnostic Tool

As this illustration shows, the Intelli-Arc base unit can be easily wired into a branch circuit associated with an AFCI, GFCI, or conventional circuit breaker. Once the base unit has been wired to a branch circuit, an electrician should follow the steps shown below.

1. De-energize all individual loads on the branch circuit that is being evaluated.

2. Find the breaker supplying the power to the branch circuit under evaluation and turn it on, but use caution.

3. Turn on the handheld device.4. Energize and then de-energize loads one by one

on the branch circuit being evaluated. Observe the LED indications on the handheld device while completing this process. Consider trying to energize and de-energize combination of loads also.

5. The “GF” and “AF” LEDs lock in the top (red) position when any event causes the device to read the maximum levels, even if the event ceases to exist. Press the “CLEAR” button to continue evaluation of the branch circuit.

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Hand-held Device Troubleshooting LEDs

Three sets of LED indicators are provided on the Intelli-Arc hand-held device for use in troubleshooting branch circuits. These LEDs show information regarding current (AMPS), ground fault level (GF), and arc fault level (AF).

Current (AMPS) LEDs• The full scale current for this LED indication is 20+ A• LED indicators do not increase by uniform intervals.• The 5A point is marked on hand-held device for reference.

Ground Fault (GF) LEDs• The full scale current for this LED indication is 50+ mA.• LED indicators do not increase by uniform levels.

Arc Fault (AF) LEDs• This LED indication does not display in the current level but rather

the severity of events. A full scale reading (red LED) indicates an event that is very likely to cause an AFCI device to trip.

• Partial readings (yellow LEDs) should be evaluated. Combined independent events may cause an AFCI to trip.

• Transitional events, such turning on an appliance, are likely to register as some low level on the arc fault scale.

• The action taken that produces the highest level of indication should be thoroughly evaluated for any issues that may be present.

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Simulators

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SITRAIN® Training for Industry

Online Self-paced Learning – Programs with maximum flexibility so students can easily fit courses into their busy schedules

Virtual Instructor-led Learning - Classroom lectures delivered in the convenience of your home or office

Classroom Learning - Expert and professional instructors, proven courseware, and quality workstations combine for the most effective classroom experience possible at your facility or ours

How-to Video Library - Quick, affordable, task-based learning options for a broad range of automation topics for training or purchase

Simulators - World-class simulation systems available for training or purchase


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For additional information including a SITRAIN world map and SITRAIN contacts worldwide: http://sitrain.automation.siemens.com/sitrainworld/Default.aspx

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Course Completion

This course covered the following topics:• Introduction• AFCI Circuit Breakers• Intelli-ARC Diagnostic Tool

This course has covered the topics shown on the left. Thank you for your efforts. You can complete this course by taking the final exam and scoring at least 70%.

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Basics of AFCI Circuit Breakers - SITRAIN LMS · 2018. 3. 7. · GFCI protection in the home is...

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