NEC prep #1

Which of the following qualifying terms indicate that a circuit breaker can be set to trip at various values of current, time, or both, within a predetermined range? A. accessible B. adjustable C. setting D. concealed

B. adjustable

A 120 volt circuit has an electric heater connected with a current rating of 7.5 amps. What is the resistance in ohms of the connected pure resistance load? A. 8 ohms B. 10 ohms C. 16 ohms D. 20 ohms

C. 16 ohms R=E/I

A voltage drop of 8.31 volts has been determined on a 277-volt lighting circuit. What percentage is the voltage drop? A. 2% B. 2.5% C. 3% D. 4%

C. 3%

What current is drawn by a 277 volt fluorescent lamp with 8 ohms resistance? A. 20.52 amps B. 60.75 amps C. 34.62 amps D. 10.30 amps

C. 34.62 amps I=E/R

A voltage drop of 19.2 volts has been determined on a 480 volt circuit. What percent is the voltage drop? A. 2% B. 2.5% C. 4% D. 5%

C. 4% 19.2/480=

A 480/277 volt, Y-connected transformer is used to supply a balanced 277 volt, single-phase lighting load of 40,000 watts. What size transformer (kVA) should be used? A. 10 kVA B. 20 kVA C. 40 kVA D. 50 kVA

C. 40 kVA

A store building 50' x 60' uses fluorescent lighting fixtures to illuminate the interior. If each fixture is to illuminate 60 square feet, how many light fixtures will have to be installed? A. 30 B. 40 C. 50 D. 60

C. 50 50x60=3000sq ft 3000/60=50

A 50kVA, three phase, delta to wye connected, 480/120-208 volt transformer is used to supply a lighting load. What is the rated phase current on the primary side? A. 45.54 amps B. 50.41 amps C. 60.21 amps D. 124.7 amps

C. 60.21 amps 50000/480x1.73=

How tall must a wall, screen, or fence be that encloses an outdoor electrical installation over 600 volts to deter access by unqualified persons? A. 5 feet B. 6 feet C. 7 feet D. 8 feet

C. 7 feet

A device designed to open and close a circuit by non automatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating is called a: A. nonfusible disconnect switch B. Time-delay fuse C. Circuit breaker D. motor running overcurrent protector

C. Circuit breaker

Which circuits must not be connected to any system containing trolley wires with a ground return? A. Ground wires B. Grounding conductors C. Circuits for lighting and power D. Ungrounded trolley wires

C. Circuits for lighting and power

A 240 volt circuit has a current flow of 20 amps. How much resistance is connected to the circuit? A. 3 ohms B. 6 ohms C. 9 ohms D. 12 ohms

D. 12 ohms

An ohmmeter shows the resistance of a 240 volt electric heater to be 19.5 ohms. What current flows through this heater? A. 10.5 amps B. 6.75 amps C. 3.2 amps D. 12.3 amps

D. 12.3 amps I=E/R

The entrance provided to give access to the working space about electric equipment rated over 600 volts must not be less than A. 6 feet by 6 feet B. 24 feet by 6 feet C. 2 feet by 6 feet D. 2 feet by 6.5 feet

D. 2 feet by 6.5 feet

The value of current, time, or both at which an adjustable circuit breaker is set to trip is known as A. inverse time B. ampacity C. automatic D. setting

D. setting

A bathroom is an area that includes a basin with one or more of the following A. exhaust fan B. AFCI C. closet D. urinal

D. urinal

Where must branch circuits and feeders be identified? A. at the disconnecting means B. at the point where they terminate C. at both the point where they originate and point where they terminate D. Midway between the outlet and overcurrent protective device

A. at the disconnecting means

According to kirchoff's voltage law which of the following Ohm's law equations may be used to find the voltage drop across a resistor? A. Voltage drop = IR B. Voltage drop = I/R C. Voltage drop = E/R D. Voltage drop = W/I

A. Voltage drop = IR

Which of the following best describes festoon lighting? A. a string of outdoor lights that is suspended between two points B. a 600 volt lighting system used in power plants C. Low voltage lighting used on billboards D. underwater lighting in pools and ponds

A. a string of outdoor lights that is suspended between two points

A point on the wiring system at which current is taken to supply utilization equipment A. an outlet B. a wall switch C. a load center D. a motor control center

A. an outlet

In locations where electric equipment would be exposed to physical damage, the following must be provided

Enclosures or Guards

A device that establishes a connection between two or more conductors by means of mechanical pressure and without the use of solder is called: A. an explosionproof connector with seal-offs B. A pressure connector C. A wire nut D. a shrink connector

B. a pressure connector

Concealed as applied to electrical wiring means

Rendered inaccessible by the structure or finish of the building

To provide access to the working space about electric equipment the following number of entrances of sufficient size must be provided

1

Externally operable means

Capable of being operated without exposing the operator to contact with live parts

A bonding conductor or jumper is

A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.

What is the maximum allowable wattage that can be connected to a 240v, 20amp, single phase circuit feeding residential electric heaters? A. 3840 watts B. 4000 watts C. 4320 watts D. 4800 watts

A. 3840 watts Maximum of 16 amps on one designated circuit for residential

If a 120 volt circuit feeds six 80 watt fluorescent lamps what current is drawn if the power factor is .91? A. 4.4 amps B. 3.2 amps C. 2.57 amps D. 4.7 amps

A. 4.4 amps 6x80=480watts 480/(120x0.91)=

What is the minimum general lighting load permitted in a 1500 square foot single family dwelling as specified in table 220.12 of the NEC? A. 4500 volt-amps B. 3500 volt-amps C. 7350 volt-amps D. 2130 volt-amps

A. 4500 volt-amps 1500 x 3=

The minimum headroom of working spaces about service equipment, switchboards, panelboards, or motor control centers shall be at least: A. 6.5 feet B. 8 feet C. 5.75 feet D. 10 feet

A. 6.5 feet 110.26

What device is now required to detect and protect against arcing in 15 and 20 amp branch circuits supplying outlets installed in dwelling units? A. AFCI B. GFCI C. GFI D. AFFI

A. AFCI

A compartment or a chamber to which one or more air ducts are connected and which forms parts of the air distribution system is a A. Plenum B. Duct C. Fan-coil unit D. Air valve

A. Plenum

A separate portion of a conduit or tubing system that provides access through a removable covers to the interior of the system at a junction of two or more sections of the system or at a terminal point of the system is defined as a: A. conduit body B. conduit junction C. conduit intersection D. conduit T-connector

A. conduit body

A device used to govern, in some predetermined manner, the electric power delivered to an electric apparatus is called a A. controller B. heater C. Governor D. motor starter

A. controller

Electric parts that are not suitably guarded, isolated, or insulated and are capable of being inadvertently touched or approached nearer than a safe distance by a person are known as: A. exposed B. externally operable C. accessible D. dead front

A. exposed

The NEC uses the term isolated to mean A. not readily accessible to persons unless special means for access are used B. Grouped together C. Identifiable by means of color coding or nameplate D. nearby

A. not readily accessible to persons unless special means for access are used

Any electric circuit that controls any other circuit through a relay is called a A. remote-control circuit B. Power circuit C. Overload relay D. Motor control circuit

A. remote control circuit

Working space in rooms containing electrical equipment shall not be used for: A. storage B. Maintenance and Repair of equipment C. Testing purposes D. Inspection or servicing

A. storage

A raceway is an enclosed channel designed for holding A. wires, cables, or busbars B. Automotive equipment C. Spark plug wires D. Equipment for high speed autos

A. wires, cables, or busbars

Approved as used in the NEC means

Acceptable to the authority having jurisdiction

A feeder is

All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.

An electric motor has an apparent resistance of 17 ohms. If a current of 7 amps is flowing through the motor, what is the connected voltage? A. 118 volts B. 119 volts C. 120 volts D. 121 volts

B. 119 volts IxR=

A 50kVA, three phase, delta to wye connected, 480/120-208 volt transformer is used to supply a lighting load. What is the rated phase current on the secondary side? A. 60.21 amps B. 138.95 amps C. 152.73 amps D. 176.54 amps

B. 138.95 amps 50000/208x1.73=

A voltage drop of 3 volts has been determined on a 120 volt circuit. What percent is the voltage drop? A. 2% B. 2.5% C. 3% D. 5%

B. 2.5% 3/120=

What is the approximate wattage of a 240 volt motor with a resistance of 28 ohms? A. 1780 watts B. 2057 watts C. 3640 watts D. 1045 watts

B. 2057 watts 240^2/28=

An incandescent lamp has a resistance of 104 ohms when 2 amps of current flow. What is the voltage? A. 240 volts B. 208 volts C. 120 volts D. 12 volts

B. 208 volts E=IR

The voltage per turn for a transformer is 1.25 volts. What is the voltage of the transformer if it has 192 turns? A. 12 volts B. 240 volts C. 120 volts D. 24 volts

B. 240 volts 192 x 1.25=

In all cases where there are live parts normally exposed on the front of switchboards or motor control centers the working space in front of such equipment shall not be less than: A. 1 foot B. 3 feet C. 4 feet unless adequate protection is provided D. 18 inches

B. 3 feet 110.26

The minimum allowable number of 120 volt, 15 amp, 2 wire lighting branch circuits required for a residence 70 feet by 30 feet are: A. 2 B. 4 C. 3 D. 5

B. 4 Find sq footage. (70x30=2100sq ft) Find volt-amps or watts (2100x3=6300w) Find amps (6300/120=52.50a) Divide by 15 amp circuits (52.5/15=3.5) round up to full amount of circuits

An electric heating element has an energized resistance of 30 ohms and is connected to a 120 volt circuit. How much current will flow in the circuit? A. 2 amps B. 4 amps C. 6 amps D. 8 amps

B. 4 amps 120/30=

How many watts of heat are being produced by a heating element with 120 volts and 4 amps? A. 550 watts B. 480 watts C. 225 watts D. 400 watts

B. 480 watts

An enclosed channel designed expressly for holding wires, cables, or busbars is called: A. A hose B. A raceway C. A receptacle D. A panelboard

B. A raceway

Parts of electric equipment which in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from: A. All other electrical equipment B. All combustible material C. Electric Lighting D. All working spaces

B. All combustible material

The NEC definition of "qualified person" is one who A. Has been elected by the inspection office B. Has skills and knowledge related to the construction and operation of electrical equipment and installations and has received safety training to recognize and avoid the hazards involved C. Has served two years apprenticeship training with a labor organization D. Has a college degree in electrical engineering or electrical technology

B. Has skills and knowledge related to the construction and operation of electrical equipment and installations and has received safety training to recognize and avoid the hazards involved

A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a class A device: A. grounding electrode device B. ground fault circuit interrupter C. guarded protector D. thermal cutout

B. ground fault circuit interrupter

Indoor electrical installations over 600 volts that are open to unqualified persons shall be made with: A. open switchgear with readily accessible live parts B. metal-enclosed equipment C. provisions to enclose the equipment within barrier less than 8 feet high D. the approval of both IBEW and the IES

B. metal enclosed equipment

What is an assembly of one or more enclosed sections having a common power supply (bus) and principally containing motor control units called? A. main distribution panel B. motor control center C. motor load center D. selector-switch control center

B. motor control center

An arrangement of incandescent lamps or electric discharge lighting to call attention to certain features such as the shape of a building is called A. festoon lighting used for outdoor parties and to highlight other outdoor functions B. outline lighting C. high-intensity discharge lighting such as normally used at intersections of highways D. decorative lighting inside a building

B. outline lighting

Where switches, or other equipment operating at 600 volts, nominal, or less, are installed in a room or enclosure where there are exposed energized parts or wiring operating at over 600 volts, the high voltage equipment shall be effectively separated from the space occupied by the low-voltage equipment by a suitable: A. warning sign B. partition, fence or screen C. voltage-reducing transformer D. Firewall

B. partition, fence or screen

How many access entrances are required to working space about electrical equipment rated 1200 amps or more and over 6 feet wide? A. one B. two, one at each end C. three, one on each of the three sides D. four, one on each four sides

B. two, one at each end

An electric oven is rated at 2000 watts when connected to a 460 volt circuit. What is the resistance of the heating element? A. 50.3 ohms B. 75.2 ohms C. 105.8 ohms D. 120.7 ohms

C. 105.8 ohms R=E^2/W

An unintentional, electrically conducting connection between an ungrounded conductor and the normally non-current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth is called A. Arc Fault B. Stray current C. Ground Fault D. High impedance

C. Ground fault

What must be provided for in all working spaces above service equipment? A. Water faucet to flush operator's eyes B. Drinking Fountain C. Illumination D. Wash basin

C. Illumination

The agency that publishes the NEC is abbreviated A. HVAC B. EEEC C. NFPA D. NRA

C. NFPA

When an enclosure has been constructed so that exposure to a beating rain will not result in the entrance of water under specified test conditions, the enclosure is known as: A. rainproof B. drip-proof C. raintight D. multioutlet assembly

C. Raintight

Any electric circuit that energizes signaling equipment is known as a A. Low-voltage branch circuit B. Multiwire circuit C. Signaling Circuit D. Feeder circuit

C. Signaling circuit

A large single panel, or assembly of panels on which are mounted switches, overcurrent and other protective devices will fall under the definition of A. General use switch B. Thermal protector C. Switchboard D. Cutout

C. Switchboard

What is a branch circuit called that supplies a number of outlets for lighting and appliances? A. An appliance branch circuit B. An individual branch circuit C. A general purpose branch circuit D. A multiwire branch circuit

C. a general purpose branch circuit

Which of the following must not be allowed to come in contact with interior parts of electrical equipment? A. busbars B. wiring terminals C. abrasives D. insulators

C. abrasives

What is the term used to describe an enclosing case that will not allow dust to enter under specified test conditions? A. dustproof B. dust prevention C. dust tight D. explosion proof

C. dust tight

Accessories such as locknuts, bushings, etc are known as A. connectors B. conduit bodies C. Fittings D. Ground clips

C. fittings

What is the name of an electrical load where the wave shape of the steady-state current does not follow the wave shape of the applied voltage? A. linear B. parallel load C. nonlinear load D. series load

C. nonlinear load

Operation of equipment in excess of normal, full load rating is known as A. hot load B. under current C. overload D. periodic duty

C. overload

A continuous load is a load where the maximum current is expected to continue for a certain length of time. This time is A. one hour or more B. two hours or more C. three hours or more D. four hours or more

C. three hours or more

When the electrical equipment exceeds 6.5 feet in height, what is the required minimum headroom? A. one foot higher than the top of the highest piece of equipment B. not less than the height of the equipment C. 6 inches or more than the height of the equipment D. 4 feet more than the height of the equipment

D. 4 feet more than the height of the equipment

Calculate the minimum volt ampere capacity of a 155,000 square foot school. A. 225 kVA B. 155 kVA C. 375 kVA D. 465 kVA

D. 465 kVA NEC 220.12

What is the minimum depth of clear working space at electrical equipment rated above 75kV and classified as condition 1? A. 3 feet B. 5 feet C. 6 feet D. 8 feet

D. 8 feet

A conductor encases within material of composition or thickness that is recognized by the NEC as electrical insulation is known as: A. bare conductor B. covered conductor C. concealed conductor D. insulated conductor

D. Insulated conductor

Which of the following anchors may not be used to secure electrical equipment to masonry walls? A. Lead anchors B. Toggle bolts C. Threaded studs shot into masonry D. Wooden plugs driven into holes in the masonry for holding wood screws

D. Wooden plugs

A contact device installed at an outlet for the connection of an attachment plug is called A. a terminator B. a junction box C. an overcurrent protection device D. a receptacle

D. a receptacle

A device which by insertion in a receptacle establishes connection between the conductor of the attached flexible cord and the conductors connected permanently to the receptacle is called one of the following: A. Female plug B. Circuit breaker C. Controller D. Attachment plug

D. attachment plug

The ratio of the maximum demand of a system, or part of a system, to the total connected load of the system or the part of the system under consideration is known as: A. percentage B. duty cycle C. Rated-load current D. Demand factor

D. demand factor

Entrances to all rooms or other enclosures containing exposed live parts operating at over 600 volts, nominal, shall be: A. elevated 30 feet above ground B. painted yellow with black and blue stripes C. kept unlocked for immediate servicing D. kept locked

D. kept locked

A bare conductor is one with

No covering or insulation whatsoever

Ampacity is defined as

The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating

What is the minimum general lighting load permitted by the NEC in a 4500 square foot warehouse? A. 1005 volt-amps B. 1125 volt-amps C. 1750 volt-amps D. 1243 volt-amps

Total volt-amps = total square feet x 0.25 volt-amps B. 1125 volt-amps