electrical test Flashcards
At buildings were communication systems are likely to be used, and inter-system bonding termination shall be provided for the communications systems at an accessible location at the service equipment. It shall be an aluminum or copper bus bar not less than 1/4 in thick by 2 in wide and be of sufficient length to accommodate at least________ terminations for communication systems in addition to other connections.
3
The ampacity of a conductor is defined by the NEC to be the maximum current, and amperes, a conductor can carry continuously under the conditions of use without exceeding__________
It’s temperature rating
I disconnect switch and closer install in a class 2, division 2 locations shall be listed as
Dusttight
The interior of enclosures or raceways install underground Shelby considered as a _______ location
Wet
Determine the ampacity (current-carrying capacity) of four size 1/0 awg THE copper current carry conductors install in a common Raceway with an ambient temperature of 86° f.
120 amperes
The NEC states each building or other structure shall have only one disconnecting means unless
The multiple disconnecting means consists of no more then six, and are housed in separate enclosures with a main service disconnecting means in each enclosure
The NEC defines a continuous load to be a load where the maximum current on the circuit is expected to be continued for at LEAST _______ hours or more
Three (3)
Given: You have determined a conductor has a computer ampacity of 74 amperes. What is the MAXIMUM standard ampere rating of the over current protection device the NEC permits to protect this circuit where this is not a motor circuit or part of a multi outlet branch circuit supplying more than one receptacle
80 amperes
A 208-vilt, 3-phase, 50 ho, squirrel-cage, continuous-duty, ac motor has a full-load running current rating of _____.
143 amperes
Which of the following is permitted in the dedicated electrical space above an indoor installed 3-phase, 480y/277-volt panelboard?
Sprinkler protection
Determine the Minimum trade size electrical metallic tubing (EMT) required to enclose eight (8) size 6 AWG copper conductors with THHW insulation, when installed in a 50 foot conduit run.
11/4 in
When exceptions are not applicable, when a feeder supplies a continuous low of 240 amperes, the overcurrent protection device protecting this circuit shall have a rating of at LEAST ______ .
300 Amperes
240 amperes x 125% = 300 amperes
Liquidtight flexible metal conduit (LFMC) shall be securely fastened WITHIN _______ space of each box or other conduit termination.
12 inches or 1’
Where a pull box to be installed will contain conductors of size 4 AWG and larger, and a straight pull of the conductors is to be made, the length of the box shall NOT be less than _______ times the trade diameter of the largest conduit entering the box.
Eight or 8
Conduit or tubing nipples not over 24 inches in length might be filled to a maximum of ______ of their cross- sectional area.
60%
Determine the MAXIMUM Number of size 14 AWG THHN conductors permitted to be installed in a trade size 3/8 in. Flexible metal conduit (FMC) that contains a bare size 14 AWG grounding conductor, when the FMC has external fittings.
4
A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected to, is recognized as a ________ in the NEC.
Controller
What is the MAXIMUM distance permitted between supports of straight runs of threaded trade size 2 in. Ridgid metal conduit (RMC)?
16 feet
A general-use snap switch with an ampere rating of NOT less than _____ shall be permitted as the motor controller for a single-phase 2 hp, 240-volt motor.
24 amperes 12 amperes x 2 = 24 amperes
Which of the following listed types of storage batteries is NOT permitted for use as a source of power for emergency systems?
Automotive. Section 700.12(C)
In guest rooms of hotels, motels, and sleeping rooms of dorms a MINIMUM of _____ general-purpose receptacles installed in the room is/are required to be readily accessible.
two 210.60(B) requires at least two
A listed _____ shall be installed in or on all emergency systems switchboards and panelboards.
surge protective device (SPD) Section 700.8 requires emergency systems panelboards and switchboards
Where a size 4 AWG or larger conductor enters a panelboard, which of the following must be provided?
An insulated bushing. Section 300.4(G) is to reduce that stress and requires an insulated bushing
Class _____ locations are those that are hazardous because of the presence of easily ignitable fibers or where materials producing combustible flyings are handled, but in which such fibers/flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitable mixtures.
III. Section 500.5(D).
A single-phase, 240-volt, 15 kVA standby generator may be loaded to a MAXIMUM of _____ per line.
62.50 amperes. 15 kVA x 1,000 = 15,000 = 62.50 amperes (1)
240 volts 240
All motors shall be considered as _____ unless the nature of the apparatus it drives is such that the motor will not operate continuously.
continuous duty. Section 430.33
Where the motor controller also serves as a disconnecting means, it shall open all _____ conductors to the motor.
ungrounded. Section 430.84
Before demand factors are taken into consideration for commercial buildings, general-purpose receptacle loads are to be computed at NOT less than _____ per outlet.
180 VA. Section 220.14(I)
Conductors with ______ insulation have a greater ampacity when used in a dry location compared to when used in a wet location.
THHW Refer to Table 310.4(A)
Isolating devices or equipment disconnecting means of solar photovoltaic systems shall be installed in circuits connected to equipment at a location within the equipment, or within sight and within at LEAST ______ of the equipment.
10 feet. Section 690.15
A single-phase, 125-volt receptacle installed to serve a washing machine in the laundry room of a dwelling unit must be installed within at LEAST ______ of the intended location of the appliance.
6 feet. Section 210.50(C)
When ambient temperature is not a factor, a size 8 AWG single copper conductor with type FEPB insulation, installed in free air, will have a MAXIMUM allowable ampacity of _____.
80 amperes. Table 310.17
For the purpose of determining conductor fill in a device box, a single-pole switch and/or a three-way switch is counted as equal to _____ conductor(s), based on the largest conductor connected to the switch.
two. Section 314.16(B)(4)
When determining the required ampacity of the branch-circuit conductors to supply a 3-phase, continuous-duty ac motor, current values given on _____ shall be used.
Table 430.250 of the NEC
Three-way and four-way switches shall be wired so that all switching is done _____.
only in the ungrounded circuit conductor. Section 404.2(A)
Determine the MAXIMUM number of size 1 AWG XHHW compact conductors permitted in a trade size 3 in., rigid Schedule 40 PVC conduit more than 24 inches long.
21.
Infrared commercial and industrial heating appliances shall have overcurrent protection NOT exceeding _____.
50 amperes. Section 422.11(C).
Class _____ hazardous locations are those in which flammable liquid-produced vapors, or combustible liquid-produced vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures.
Class I locations are those locations where the handling or processing of volatile flammable liquids such as gasoline or flammable gases such as propane take place
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.
1/4 in. Section 300.6(D)
Armored cable (Type AC) installed horizontally through wooden or metal framing members is considered supported where the support doesn’t exceed _____ intervals.
4½ feet. Section 320.30(C)
What is the MAXIMUM overcurrent protection allowed for the protection of resistance-type electric space heating equipment?
60 amperes. Section 424.22(B).
Information technology equipment shall be permitted to be connected to a branch circuit by a listed power-supply cord having a length NOT to exceed _____.
15 feet. 645.5(B)(1)
All 125-volt, single-phase, 15- or 20-ampere receptacle outlets installed within at LEAST _____ of the outside edge of a dwelling unit bathtub or shower stall require GFCI protection.
6 feet. Section 210.8(A)(9)
The purpose of an intersystem bonding termination is to provide a means for connecting _____ to the grounding electrode system.
bonding conductors for communications systems.
Direct-buried conductors emerging from grade shall be protected by raceways or covers up to at LEAST _____ above finished grade.
8 feet. Section 300.5(D)(1)
What is the MINIMUM size wire type equipment grounding conductor for a 50 ampere branch circuit as required by the NEC?
10 AWG. Section 250.122 equipment grounding conductors
Disregarding exceptions, all 3-phase, 4-wire, 480Y/277-volt, electrical services, require ground-fault protection for each service disconnecting means when rated for at LEAST _____ or more.
1,000 amperes. Section 230.95
Determine the conductor ampacity given the following related information:
conductors are size 500 kcmil copper
conductor insulation is THWN
eight (8) current-carrying conductors are in the raceway
ambient temperature is 125 deg. F
conduit length is 50 feet
installation is a wet location
178.2 amperes.
Size 500 KCMIL THWN copper ampacity before derating =
380 amperes
380 amperes x .67 (temp. correction) x .7 (adjustment factor) = 178.22 amperes
When connecting to luminaires, trade size 3/8 in. flexible metal conduit (FMC) is permitted to enclose tap conductors, provided the length of the FMC does NOT exceed _____.
6 feet. Section 348.20(A)(2)
