NEC Flashcards
In metal water pipe that runs in your ground can serve as he grounding electrode if it is in direct contact with the Earth for at least how many feet or more?
10ft.
Back book. Water pipe. As grounding electrode.
An electric motor is running on 120V. The current is measured to be 2 A. How many ohms is the motor?
60ohms
An electrical circuit has a voltage of 50 V and a resistance of 5 ohms. What is the value of the current?
10 amps
Current that flows in only one direction is called unidirectional. It is also referred to as ____ current.
Direct
In opposition to current flow that occurs in alternating current circuits is called ___?
Current
Fire alarm cable must be protected by metal raceway or rigid nonmetallic conduit up to what height from the floor?
7ft.
760 cuzz that’s install
For conductors not in enclosures or hoist ways, power limited a fire alarm cable shall be separated from electrical light and power common class one and NLFA cables by a minimum of?
2 inches.
Backbook.
Remote control signaling and power limited.
Separation
Given a parallel circuit with 3 resistors, each measuring 15 ohms, What is the total resistance of the circuit?
5 ohms.
Ohms÷resistor
Given a series circuit with 3 resistors, each measuring 20ohms, what is the total resistance of the circuit?
60 ohms
Series = times
Grounding conductors for equipment shall be what color?
Bare wire, green or green with one or more yellow stripes
250.119
Back book. Grounding conductors. Identification
If one of the parallel paths is broken, current will not continue to flow in any other path.
True or false?
False
In a series circuit the amperage at any point in the circuit is the same
True. False?
True
In order to have current flow the circuit must be
A.closed
B.open
C.shorted
D.grounded
A. Closed
NON POWER LIMITED fire alone cable shall have an insulation rating of not less than how many volts?
600 V MINIMUM
Opposition to current flow is called what?
Resistance
Power sources for Power-Limited fire alarm circuits must be protected by an over current device not rated more than how many amps?
20amps.
760.121
Back book. Fire alarm systems. PL. Power sources
The accessible portion of abandoned fire alarm cable must be?
Removed
The sum of the currents through each path = the total current that flows from the source?
True or false
True
The units of electrical “pressure” that causes current to flow is called the ___?
Volt
The unit of elwctromotive force is the __?
Volt
Voltage is the ____ in each branch of the parrallel circuit.
A.not the same
B.the same
C. Higher than v
D. Half the v
B.the same
What is the minimum depth a ground rod is required to be driven in the soil?
8ft
What is the minimum size grounding electrode when made of pipe or conduit?
3/4 inches
A class 1 circuit conductor shall have a minimum insulation rating of how many volts?
600v
NEC 725.49
(B)
For class one circuits, where are over current devices required to be located?
at the point where the conductor to be protected receives its supply
725.45 (A)
What is the maximum rated output allowed for a class one power limited circuit?
Not more than 30v and 1000 volt-amperes
Part II class 1 circuits
What is the minimum allowable AWG for a class 3 single conductor
18 AWG.
If one of the parrallel parhs is broken, current will not continue to flow in any other path.
True or false
False
If more than one electrode is used, each electrode of the grounding system must not be less than how many feet? from any other electrode of another grounding system
6 feet
If you try to drive a grounding rod and you hit solid rock, you are permitted to bury the grounding rod and a trench that is at least how deep?
30 inches
What is the minimum allowable AWG for a class 3 conductor?
18AWG
What is the required overcurrent protection for an NPLFA circuit Is using 18 gauge wire?
7A
Power sources for power limited fire alarm circuits must be protected by an overcurrent device not rated at more than?
20amps
