Unit 6: Voltage Drop Calculations Flashcards
Using NEC® guidelines and formulas to calculate voltage drop in conductors, ensuring efficient power distribution and minimizing energy loss in electrical circuits.
According to Ohms Law, what is the electrical unit of current?
ampere
Fill in the blank:
The NEC® definition of ________ is “connected to establish electrical continuity and conductivity”.
bonded (bonding)
Fill in the blank:
In addition to the number of 120-volt, single-phase branch circuits required in other areas of a dwelling, at least one additional ________ branch circuit shall be provided to supply the laundry outlet in the laundry room.
20-amperes
Fill in the blank:
Where rigid metal conduit (RMC) or intermediate metal conduit (IMC) is threaded in the field where corrosion protection is necessary, the threads shall be coated with a/an ________ compound.
approved electrically conductive, corrosion-resistant
Fill in the blank:
In a straight run of rigid Type PVC conduit, expansion fittings are to be provided to compensate for thermal expansion and contraction where the length change is expected to be at least ________ or greater.
1⁄4 in.
What is permitted in the dedicated electrical space above a panelboard?
leak protection and sprinkler protection
Fill in the blank:
For other than submersible types of motors, they shall be located so that adequate ________ is provided and so that maintenance, such as lubrication of bearings and replacing of brushes, can be readily accomplished.
ventilation
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For bathtub and shower areas, no parts of cord-connected luminaires, lighting track or ceiling-suspended (paddle) fans shall be located within a zone measured ________ horizontally from the top of the bathtub rim or shower stall threshold.
3 feet
Fill in the blank:
Given: After all demand factors have been taken into consideration, a one-family dwelling with a 120/240-volt, single-phase electrical system has a demand load of 35,000 VA. The MINIMUM size THWN copper phase conductors required for an underground installed service is ________.
2 AWG
I = 36,000 VA/240 volts
= 145.8 amperes x .83
= 121 amperes
Size 2 AWG copper conductors with an ampacity of 125 amperes should be selected from Table 310.12.
True or False:
In general, when sizing the overcurrent protection, disconnect size, and supply circuit conductors for a motor used in a continuous-duty application, they shall be sized based on the full-load running current of the motor given in the Tables of the NEC.
TRUE
Fill in the blank:
Continuous-duty motors, more than one hp, with a marked service factor less than 1.15 shall have the MINIMUM running overload protection sized at ________ of the nameplate rating of the motor, where modification of this value is not necessary.
115 percent
Fill in the blank:
Mobile home service equipment shall be located in sight from and NOT more than ________ from the exterior wall of the mobile home it serves.
30 feet
Fill in the blank:
As a general rule, switches or circuit breakers shall ________.
not disconnect the grounded conductor of a circuit
What is the MINIMUM number of 120-volt, 20-ampere, single phase branch-circuits that must be provided to supply receptacle outlets in dwelling units?
five
Fill in the blank:
Small gage conductors such as a single size 16 AWG conductor is permitted to carry continuous loads up to ________, as long as the conductor is protected by a fuse or circuit breaker.
8 amperes
Fill in the blank:
The accessible portion of abandoned supply circuits and interconnecting cables located in an information technology equipment room shall be removed, UNLESS ________.
contained in a raceway
Fill in the blank:
Generally, in dwelling units, where one or more lighting outlets are installed for interior stairways, there shall be a wall switch at each floor level, and landing level that includes an entryway, to control the lighting outlets where the stairway between floor levels has at LEAST ________ risers or more.
six
Fill in the blank:
A receptacle installed outdoors in a location protected from the weather or in other damp locations shall have an enclosure for the receptacle that is ________ when the receptacle is covered (attachment plug cap not inserted and receptacle covers closed).
weatherproof
True or False:
A fused disconnecting means for motor circuits rated 1000 volts or less, shall have an ampacity of at LEAST 115 percent of the full-load current rating of the motor it disconnects.
TRUE
Determine the current, in amperes, on the circuit conductors for a 208Y/120-volt, 3- phase system where each phase is balanced with a 2,500 VA load and the total load is 7,500 VA.
20.82 amperes
I = VA ÷ volts x 1.732
I = 7,500 VA/208 x 1.732
= 7,500/360.25
= 20.82 amperes
Fill in the blank:
No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless the overcurrent device or circuit breaker ________.
simultaneously opens all conductors of the circuit including the grounded conductor
Fill in the blank:
For temporary wiring installations that have an assured equipment grounding conductor program, all required tests shall be performed at intervals NOT exceeding ________.
3 months
Fill in the blank:
For continuous-duty motors, the motor nameplate current rating is used to determine the size of the ________ required for the motor.
motor overload protection
Fill in the blank:
GFCI protection for personnel is required where a 125-volt, single-phase, receptacle is located on a wet bar countertop if within ________ from the top inside edge of the bowl of the sink.
6 feet
