TEST 11 Flashcards
An arching fault current in a 480/277V wye system can be as low as _____% of the 3 phase bolted fault current without self-extinguishing
38
The primary role of overcurrent protection is to protect _____
conductors
A ______ fault condition has a relatively high resistance path that results in a lower fault current then worst case
arcing
a _____ is defined as operation of equipment in excess of normal, full load rating, or of a conductor in excess of rated ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating
overload
The voltage rating of the OCPD must be at least equal to or greater than the circuit _____.
voltage
The rating which defines the capacity of an OCPD to maintain it integrity when reacting to fault currents is referred to as its _____
interrupting rating
the interrupting rating of an overcurrent protective device represents its ability to protect circuit components located downstream of the OCPD
false
OCPD markings include
interrupting rating
ampere
voltage
trademark or name
For a circuit breaker to trip, due to an overcurrent, the ____ must sense the overcurrent and release the contacts
trip unit
the types of molded case circuit breakers include
electronic
thermal magnetic
magnetic only trips
a ____ protective device is one which cuts off a fault current in less then one-half cycle
current limiting
Under normal operation when the fuse is operating at or near its ampere rating, it simply functions as a _____
conductor
article 240 requires overcurrent protection in each ___ conductor locate at the point where the conductor receives its supply or at an alternative location in the circuit when designed under engineering supervision
ungrounded
