2. Annually, 40,000 fires - 300 deaths -
over 1,400 injuries
Arcing faults are the major cause of
residential fires.
In 1994 an insurance company survey
of 660 electrical fires indicated that
over 33% of these fires were from
arcing condition.
An arc fault is the flow of electricity
over an unintended path.
3. Unwanted arcing generates high
temperatures and discharges molten
metal that can ignite nearby
combustibles such as paper, insulation,
vapors, and carpets.
Temperature -several thousand degrees
Celsius depending on the available
current, voltage, and materials
involved.
6. An arc will not jump an air gap and
sustain itself unless there is at least
350 V across the gap.
Therefore, in 120/240 V ac systems, it
is difficult for arcing to cause ignition
unless arc tracking occurs, or the
electrodes loosely contact each other
causing a sustained arcing fault.
7. Two basic types of arcing
faults
Series arcing faults
Parallel arcing faults
8. •Occur when the current-carrying path in series
with the load is unintentionally broken.
•Arcing may occur across the broken gap and
create localized heating.
•The magnitude of the current in a series arc is
limited by the load.
Series Arcing Faults
9. •The series arcing currents are below the
typical circuit breaker’s ampacity rating
(handle rating) and, therefore, would never
trip the conventional circuit breaker either
thermally or magnetically.
10. Series arcing can lead to overheating that can
be hazardous.
Example:
- loose connections to a receptacle or a wire splice
- a worn conductor from over flexing of a cable.
11. Parallel Arcing Faults
Occurs when
there is an
unintentional
conducting path
between
conductors of
opposite polarity.
13. An ordinary circuit breaker
• protects electrical branch circuit wiring.
• reduce the risk of fire from overheating.
the heat generated by an
overload or fault damages the
wire's electrical insulation the
heat generated by an overload
reaches temperatures that could
result in a risk of fire.
14. •At overload condition,
the current drawn by the
sum of the electrical
loads , connected to a
particular circuit,
exceeds the current
capacity (ampacity) of
the circuit conductors.
16. Objectives
1.Discuss the operating theory of AFCI
2.Explain the importance of AFCI in house
wiring installation
3.Identify the types of AFCI
4.Illustrate the proper connection of AFCI
breaker in a wiring system
5.Appreciate the value of teamwork and
collaboration in learning the lesson
17. Designed to prevent fires
by detecting a non-working
electrical arc.
Disconnect the power
before the arc starts a fire.
It should distinguish
between a working arc and
a non-working arc that can
occur.
18. Arc Faults Arise From A Number of Situations including:
• Damaged Wires
• Receptacle Leakage
• Worn Electrical Insulation
• Loose Electrical Connections
• Shorted Wires
• Wires Or Cords In Contact With Vibrating Metal
• Overheated Or Stressed Electrical Cords And
Wires
• Misapplied/Damaged Appliances
19. Now Reflect!
From the presented
topics, I want you to
reflect about the
importance of AFCI
in a wiring system.
21. An AFCI is selective so that normal
arcs do not cause it to trip.
It circuitry continuously monitors
current flow through the AFCI to
discriminate between normal and
unwanted arcing conditions.
22. *An AFCI should not trip
during normal arcing
conditions, which can occur
when a switch is opened or a
plug is pulled from a
receptacle.
23. AFCIs have a test button and look
similar to ground fault circuit
interrupter circuit breakers.
Some designs combine GFCI and
AFCI protection.
AFCIs are designed to mitigate the
effects of arcing faults but cannot
eliminate them completely.
24. The AFCI circuit breaker serves a dual
purpose –
shut off electricity in the event of an
“arcing fault”
trip when a short circuit or an overload
occurs.
25. The AFCI circuit breaker
provides protection for the branch
circuit wiring and limited
protection for power cords and
extension cords.
Single-pole, 15- and 20- ampere
AFCI circuit breakers are
presently available.
28. 1. BRANCH/FEEDER
AFCI
Installed at the origin of
a branch circuit or feeder,
such as at a panel board.
Provide protection of the
branch circuit wiring,
feeder wiring, or both,
and branch circuit
extension wiring. against
unwanted effects of
arcing.
29. It may be a circuit- breaker-type device or
a device in its own enclosure mounted at
or near a panel board.
30. 2. OUTLET CIRCUIT AFCI
Installed at a branch circuit outlet, such as at an
outlet box.
Provide protection of cord sets and power-supply
cords connected to it (when provided with receptacle
outlets) against the unwanted effects of arcing.
31. 3. COMBINATION AFCI
Complies with the requirements for both
branch/feeder and outlet circuit AFCIs.
Protect downstream branch circuit wiring and
cord sets and power-supply cords.
34. WHERE AFCIs SHOULD BE USED?
•Receptacle outlets in bedrooms
•Panel box while using existing
branch circuit conductors.
35. Let’s Synthesize
Answer the following questions in your journal
notebook for 10 minutes.
1. How is the AFCI breaks the fault current
in the system?
2. Differentiate the types of AFCI.
3. Illustrate the installation of AFCI Breaker
Usually accompanied by the partial volatilization of the electrodes.
Some arcs are a normal consequence of device operation.
Certain devices are designed to contain arcs from combustible surroundings. Other arcs are unwanted.
For arcs in electrical distribution systems, the insulating medium is an air gap, wire insulation, or any other insulator used to separate the electrodes or line and neutral conductors.
Conventional circuit breakers only respond to overloads and short circuits, so they do not protect against arcing conditions that produce erratic current flow.
Once an unwanted arcing condition is detected, the control circuitry in the AFCI trips the internal contacts, thus de-energizing the circuit and reducing the potential for a fire to occur.
In some cases, the initial arc may cause ignition prior to detection and circuit interruption by the AFCI.
