Code Flashcards
Can a short circuit be a ground fault OR a line to line fault?
yes
are overcurrent and overload devices the same thing?
no
What is the formula for short circuit current?
I Secondary/%IZ
A 15A circuit breaker trips when 20A current flows through it over a period of time. Is this due to overload or overcurrent?
overload
Do fuses need an interrupting rating?
yes
If there is no interrupting label listed, what do we assume it is?
10,000 A
What is the max current we can use plug fuses for?
30A
Is it possible to use a 60A fuse holder for a 25A fuse?
no
Does a dual element fuse provide a time delay?
yes
Can fuses protect for both short circuit and overload?
yes, if they are a dual element
Must time delay fuses be marked with TD?
yes
What is the interrupting capacity of class H fuses?
10,000A
Can we replace a class H fuse with a class K for a higher interrupting rating?
Yes, we sure can
A circuit breaker is a manual control device as well as an overcurrent device. True or False?
True
The electromagnetic component of a circuit breaker responds to what?
short circuits
The Thermal component of a circuit breaker responds to what?
overload
What must be put on receptacles within 1.5m of kitchen sinks?
Class A GFCI
AFCI protects against series and parallel low level arcing faults. True or False?
True
What two conditions must protective devices operate automatically?
overload and short circuit
In a proper selectively co-ordinated system, the overcurrent device that trips first will be the:
branch circuit
Can you install a circuit breaker that does not have an interrupting rating equal or greater than the available fault current of the circuit if part of a series rated combination?
Yes
What are the standard sizes for disconnects?
30, 60, 100, 200, 400, 600,
If in doubt, what size is our grounding conductors?
6AWG
Due to inverse time characteristics, circuit breakers and fuses will open ____ when heavily overloaded and ____ when slightly overloaded
quickly, slowly
What size of disconnect would be required for a 70A fuse?
100A
Are kitchen counter receptacles required to be protected by an AFCI
fuck no
Which electrical distribution design would have the lowest fault current?
Radial
Which electrical distribution design is for residential?
Radial
Which electrical distribution design would you likely find downtown?
Network
What is the advantage of a network system?
100% up time. If you had to shut down a transformer, the clients wouldn’t lose power
What is the disadvantage of a network system?
Super high fault currents
How do GFCI’s work?
If the current leaving does not equal the current coming back, they trip
What are two ratings that are evaluated when determining the suitability of an overcurrent?
continuous and interrupting
Class H fuses are very uncommon because:
they have a very low interrupting rating
Are series rated systems constructed from fuses, breakers or both?
breakers only
What is an overload condition?
a moderately higher current than normal
What is a short circuit condition?
Much, much higher current than normal
Describe continuous rating
Higher than designed load for circuit
Describe interrupting rating
Must be higher than the available fault current. If it is not, it will explode
Where does current always travel back to?
the source
What determines the current of the circuit?
the load
What is considered an electrical source?
Transformers, generators, inverters, batteries, solar
What is considered to be the ungrounded conductor?
the hot, line, phase a/b/c
What is considered to be the grounded circuit conductor?
The neutral/identified/identified neutral/white
What is the difference between hot sequence and cold sequence metering?
hot sequence = meter is on supply side
cold sequence = meter on the load side
What are three types of grounding electrodes?
manufactured, field assembled, in situ
What is an example of a manufactured grounding electrode?
a rod or plate
GFCI’s can be:
deadfronts, breakers, receptacles
AFCI’s can be:
deadfronts, breakers, receptacles
What makes up a motor starter?
Overload and a contactor
Which insulation class is the hottest?
H
What is the hottest kind of wire?
SES110
What are the overload multipliers?
125% for SF 1.15 and above
115% for SF 1.14 and below
What are some things that can be found on a motor nameplate?
Type, insulation class, voltage, FLA, service factor, duty, etc
What is the supply conductor in a motor circuit?
The conductor between the JB and the motor
Where does the motor supply conductor connect?
directly to the motor
Is the controller considered a disconnect?
hell no
