Lesson 110 Homework: Voltage Drop, Cable, Conduit, and Tubing
The maximum distance permitted between a box and the first strap (support) for an installation using 1" LFMC (liquidtight flexible metal conduit) is ____ ft.
1
Cables run parallel to (along) or through holes bored in framing members must be at least ____ from the edge of the framing member.
1 1/4 inches (32 mm)
What size equipment grounding conductor is contained in 10-3 Type MC cable?
10
A branch circuit for a copy machine has 124 volts available at the circuit breaker. Because the copier draws 15.4 amps, there is a total of 13.2 volts dropped in the branch circuit conductors. With the copier operating, the voltage that would be measured at the receptacle where the copy machine is connected would be ____ volts.
110.8
Your body is a better conductor when ____.
you are sweating
The support requirements for ENT are located in the NEC® in Section ____.
362.30
You have to run a 240-volt circuit to a 24-amp load that is located 321 feet away from the panel. The smallest size wire you can pull in for the circuit is ____ AWG. The voltage drop can't exceed 4.8 volts. Use K = 10.9.
4
Horizontal runs of trade size 3 Schedule 40 PVC conduit must be supported at ____ ft intervals.
6
What is the maximum distance permitted between straps (supports) where 12-2 Type MC cable is run for some distance between boxes or enclosures? ____ feet.
6
What is the percentage of voltage drop on a 120-volt circuit? 12 AWG copper conductors were used and the load draws 20 amperes. The distance from the panel to the load is 100 feet. Use K = 12 to calculate the voltage dropped in the conductors.
6%
What is the voltage drop on a 120-volt circuit? The circuit uses 12 AWG copper conductors and has a load of 20 amperes. There is a distance of 100 feet from the panel to the load. (Use K=12)
7.35 volts
Six 20 watt, 12-volt luminaires (lighting fixtures) are supplied from a small, 12-volt transformer that is 60 feet away from the fixtures. The wire used is 14 AWG. What is the voltage applied to the fixtures? Use K = 11.6.
8.61
The NEC® requirements for securing Schedule 40 PVC in horizontal runs are located in Section ____.
352.30
A 13.9-amp, 240-volt load is connected to a 2-pole circuit breaker in a 120/240-volt, 1Ø, 3-wire panelboard using 12-2 AC cable. Use K = 11.3 and limit the voltage dropped in the circuit conductors to 2.5%. The maximum length of the cable that can be used for the circuit is ____ feet.
124
In the NEC®, voltage drop for branch circuits is covered in ____.
210.19(A) I-Note 4
What is the cross-sectional area, in circular mils, of a copper conductor needed to supply a circuit 75 feet from the panel, with a load of 50 amperes and a voltage drop not to exceed 3.5 volts? (Use K=12)
25,714
Refer to Figure 110.16. You are to run 320 feet of PVC underground from a panel to a 30-foot-tall parking lot light pole. Install copper THHN/THWN circuit conductors from the breaker to the luminaires on top of the pole. The luminaires will draw a total current of 15.182 amps. The voltage measured at the circuit breaker is 211 volts. In order to supply at least 208 volts to the luminaires, the smallest size wire is ____ AWG. Use NEC® Chapter 9, Table 8 and K=12.
3
Using 12-2 MC cable with interlocked armor that has an overall diameter of 1/2", what is the minimum dimension as shown at ? in Figure 110.12?
3 1/2"
The Code recommends a voltage drop no greater than ____ percent for feeders and no greater than ____ percent total for feeders and branch circuits together.
3 5
EMT shall be securely fastened in place at least every ____. In addition, each EMT run between termination points shall be securely fastened within ____ of each outlet box, junction box, device box, cabinet, conduit body, or other tubing termination.
3 m (10 ft), 900 mm (3 ft)
What is the voltage drop on a 120-volt circuit consisting of 10 AWG copper wire where the load is 30 amps and the distance between the panel and the load is 50 ft? (Use K=12)
3.46
According to the NEC®, what is the largest size of flexible metallic tubing (FMT) that can be used?
3/4 inch
____ is the Code Article that provides the requirements for Type AC cable.
320
The NEC® requirements for securing Type AC cable entering or exiting a box are located in Section ____.
320.30
When doing voltage-drop calculations, where is the cross-sectional area in circular mils located?
Chapter 9, Table 8
If circuit current travels through your body, the circuit breaker will trip. This is a ____ statement.
False
For Type MC cable, is the insulated green conductor permitted to be used as a current-carrying circuit conductor?
No
When Type MC cable is installed in horizontal runs through the holes in sheet metal studs and joists, do additional supports have to be installed (Caddy clips for example)? The MC cable is securely fastened within the required distance from any boxes or enclosures and the framing members are on 24" centers.
No
Which of the following wiring methods provides the best protection against physical damage?
Rigid
Trade size 1 Schedule 40 and Schedule 80 PVC use the same fittings (couplings and connectors). Note: PVC "connectors" are properly identified as male or female adapters.
True
When MC cable is used as the wiring method, the fittings used with the MC cable are required to be listed for MC cable.
True
Support and physical protection requirements for Type AC cable are similar to those for ____.
Type NM cable
A 3-foot long piece of LFMC (liquidtight flexible metal conduit) will be installed to connect a motor that is going to vibrate. Does the NEC® require that a separate equipment grounding conductor be installed?
Yes
A 4-foot long piece of FMC (flexible metal conduit) will be installed to connect a motor that is going to vibrate. Does the NEC® require that a separate equipment grounding conductor be installed?
Yes
Electricity can cause ____.
blisters burns your muscles to contract
If someone else has come in contact with a circuit, the first thing to do is to ____.
break the circuit
When there's a current leakage from a tool or piece of equipment, the current will flow through any available ____ until it reaches a grounded surface or grounding conductor.
conductor
When circuit resistance is increased, such as when corrosion develops at wire nut terminations, the flow of electrons in a circuit is ____.
decreased
When making connections to motorized appliances such as food waste disposers, washers, dryers, air-conditioners, and heat pumps that may be subject to vibration, ____ is an acceptable choice for the wiring method.
flexible metal conduit
Type AC cable is manufactured with ____ circuit conductors (excluding ground).
four, three, two
A(n) ____ is required for all construction personnel while using 15- or 20-amp, 120-volt receptacles. It shuts off electricity if a ground fault occurs.
ground-fault circuit interrupter
As the length of wire in a circuit increases, the circuit resistance ____.
increases
The voltage (volts) dropped in circuit conductors ____ when the circuit length is increased.
increases
Armored cable includes a(n) ____ to ensure a low-impedance grounding path.
internal bonding strip
When connections to motorized appliances such as food waste disposers, washers, dryers, air-conditioners, and heat pumps that may be subject to vibration are made, ____ is an acceptable choice for the wiring method.
liquidtight flexible nonmetallic conduit
You can count on being safe around ____ voltages.
none of these
Alflex® Type NM liquidtight flexible nonmetallic conduit can be installed ____.
outside in the sunlight where the temperature is -15°F in a concrete slab
Voltage drop problems can be caused by any of the following conditions: • wire too small for load served •circuit conductors too long •poor or corroded connections at terminals •conductors operating at high temperatures (higher temperatures increase resistance) The presence of one or more of these conditions causes an increase in the total ____ of the circuit.
resistance
What could happen if electrical current uses your body as a part of the ground return path?
slight tingle sudden death
Leakage current wants to get to ____.
the power souce
