Voltage Drop
What is the maximum load permitted on a 115V single phase branch circuit using #12 THW stranded conductors 150' from the source?
5.80A
A conductor with THHN marked on the insulation has a temperature rating of ______.
90ºC
Where a conduit or tubing longer than 24 inches contains two (2) ungrounded conductors, one (1) grounded conductor and one (1) equipment grounding conductor, the conduit is permitted to be filled to a maximum _____ of its cross-sectional area.
40%
A single-phase, 120/240 volt, 18 kW rated home standby generator has a full-load current rating of _____.
To solve this problem apply the single-phase current formula as follows:
I = power/Volts
I= 18kW X 1000/ 240V =
18,000/ 240 = 75A
In indoor areas where walls are frequently washed, such as laundries or car washes, metallic conduit and metallic panelboards shall be mounted with a minimum _____ space between the wall and conduit or panelboard when the equipment is installed exposed.
According to Section 300.6(D), in commercial or industrial facilities where walls are frequently washed, all metallic boxes, raceways, panelboards and fittings shall be mounted so that there is at least ¼ in. airspace between it and the wall to prevent corrosion.
What size conductor for a single phase 1 1/2hp 230V motor with a full load current of 10A 150' from the source?
#12 THW
Direct-buried cables or conductors located in a trench below two (2) inch thick concrete or equivalent shall have a minimum cover requirement of _____.
18"
Unless specifically identified for a higher percentage of fill, the cross-sectional area of the conductors or optical fiber tubes in a conduit seal, in Class I, Divisions 1 and 2 locations, shall not exceed _____ of the cross-sectional area of a rigid metal conduit (RMC) of the same trade size.
25%
Where a 15-ampere rated general-use ac snap switch is used as a disconnecting means for an ac motor, the NEC requires the full-load current rating of the motor to be no more than _____ .
12A
All nonlocking-type, 125-volt, 15- and 20-ampere receptacles located in guest rooms of hotels and motels and their common areas shall be listed _____ receptacles.
Tamper Resistant
The voltage drop on two #12 solid uncoated THW conductors, 150' long, connecting a 9.8 amp load to a 115V source would be _____ volts.
5.6742V
The maximum unsupported and unsecured length of Type MC cable used to supply a luminaire in an accessible ceiling is permitted to be not more than _____ in length.
6'
Determine the ampacity of a size 2 THHN copper conductor to be installed in a conduit of more than 2 ft. in length with 3 other current-carrying conductors in an ambient temperature of 115°F.
85A
Where voltage drop and ambient temperature are not a consideration, the conductors used to supply a continuous-duty, 3-phase, 208-volt, Design C, 10 hp, induction type motor are to have an ampacity of not less than _____.
38.5
Equipment supplied by Class 1 circuits such as fire alarm, control, and signaling circuits shall be grounded, unless operating at less than _____ .
50V
What is the voltage drop on a branch circuit to a load of 11 amps location 175' from the 208V single phase source using #8 THW stranded copper conductors?
2.9953
What is the maximum voltage permitted between branch-circuit conductors supplying luminaires in a residence or guest rooms of hotels and motels?
120V
Unless specifically identified for a higher percentage of fill, the cross-sectional area of the conductors or optical fiber tubes in a conduit seal, in Class I, Divisions 1 and 2 locations, shall not exceed _____ of the cross-sectional area of a rigid metal conduit (RMC) of the same trade size.
25%
Determine the initial rating or setting, in amperes, of the overload relays required for protecting a 3-phase, 208-volt, 15 hp, continuous-duty, induction-type motor. The motor nameplate is marked with: 45 FLA, temp. rise 40°C and service factor 1.15. Assume the value you select is sufficient to start the motor and carry the load and modification of this value is not necessary.
56.25A
A bonding jumper connected between the communications grounding electrode and power grounding electrode system at the building or structure service where separate electrodes are used shall not be smaller than size _____ copper.
#6 AWG
What size THW conductor is required for a 208V 3 phase branch circuit that has a 15 amp load located 180' from the source?
#10
or one-family dwellings supplied by a single-phase 120/240-volt system the service-entrance conductors are permitted to be sized at not less than _____ of the service demand rating, if no adjustment or correction factors are to be applied.
83%
The ampacity of phase conductors from the generator terminals to the first overcurrent device shall not be less than _____ of the nameplate current rating of the generator where the design of the generator does not prevent overloading.
115%
What size 75ºC copper feeder conductors are required to supply the following group of 3-phase, continuous-duty, 240-volt ac motors?
Size 4 AWG THWN conductors with an ampacity of 85 amperes should be selected from Table 310.16
What percent of electrical supplied spaces in a recreational vehicle park must be equipped with at least one (1) 30-ampere 125-volt receptacle outlet?
70%