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
Ohms Law
I = voltage ÷ ohms = amperes
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-ampere
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.
Which of the following shall be permitted in the dedicated electrical space above a panelboard?
a. air-conditioning ducts
b. leak protection
c. piping
d. sprinkler protection
d. 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
Fill in the blank:
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
Single-phase Current Formula I = P ÷ E
I = 36,000 VA = 145.8 amperes x .83 = 121 amperes
240 volts
Size 2 AWG copper conductors with an ampacity of 125 amperes should be selected from Table 310.12(A).
When doing feeder and service calculations, the value to be included for each unit of electric vehicle supply equipment (EVSE) shall be either _____ or the nameplate rating of the equipment, whichever is larger.
7200 watts (volt-amperes)
What is the demand load, in kW, on the ungrounded (line) service-entrance conductors for a 10 kW household electric range?
8 kW
Fill in the blank:
In compliance with the Code regarding hazardous (classified) locations, conduit and fittings shall be made wrench-tight to _____.
prevent sparking when a fault current flows through the conduit system
True or False:
As a general NEC rule, switches or circuit breakers shall disconnect the grounded conductor of a circuit.
FALSE
What is the required 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, for 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
Fill in the blank:
A fused disconnecting means for motor circuits rated 1000 volts or less, shall have an ampacity of at least _____ of the full-load current rating of the motor it disconnects.
115 percent
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
3-phase current formula
I = VA ÷ volts x 1.732
I = 7,500 VA = 7,500 = 20.82 amperes
208 x 1.732 360.25
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:
The Code explains the service equipment for a mobile home is to be mounted in a readily accessible outdoor location, insight of the mobile home it serves and _____.
within 50 feet from the exterior wall of the mobile home
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
