Specifications

15
AFCI Circuit Breaker Arc faults are electrical arcs which result when current flows in
unintended ways, but, in residential applications, often not in
sufficient amounts to cause a standard circuit breaker to trip.
Arc faults in residential applications typically result from worn or
damaged insulation and are a common cause of fires.
An arc fault circuit interrupter (AFCI) circuit breaker protects
against a fire being started by arc faults by recognizing the
characteristics unique to arcing and de-energizing the circuit
when an arc fault is detected. Not all AFCI circuit breakers are
the same, however.
Combination type AFCI (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, and series arcs greater
than or equal to 5 A. Series arcs are arcs on a single conductor.
Parallel Arc
>
75 A
Series Arc
>
5 A
Line-to-Ground Arc
Load
Load
(Line-to-Neutral)
Load
Neutral Neutral Neutral
QT Circuit Breakers Some Siemens load centers are designed to accept type QT
Duplex, Triplex, and Quadplex plug-in circuit breakers. These
are space saving breakers that are half the width per pole of type
QP circuit breakers. This reduced width allows more circuits to
be serviced from a load center, provided that the main circuit
breaker has sufficient capacity. An important use for QT breakers
is in cases where additional circuits are being added to an
existing load center, but not enough spaces are available in the
load center.
QT Duplex
Two Independent 1-Pole Breakers
Requires One Space
QT Quadplex
Two Sets of Common Trip 2-Pole Breakers
Requires Two Spaces
QT Triplex
Two Independent 1-Pole Breakers
One Common Trip 2-Pole Breaker
Requires Two Spaces