3rd year first semester midterm

The minimum size of an equipment bonding jumper on the load size of an overcurrent device shall be in accordance with the sizes limited in table

250.122

Which of the following tables is used to select a load side equipment bonding jumper?

250.122

A 120/240 volt 1 phase 3 wire service is to be run to serve 400 A main breaker panel B. Two parallel conduits will be ran. Panel B serves the following loads. 22 amps of 240 volt loads. 122 amps of 120 volt loads are connected to a phase and 188 are connected to B phase. The grounded conductor permitted in each of the paralel conduits will carry ____ amps

66

Under conditions of maximum ground fault current flow, an effective equipment grounding system should ______. i.maintain a low potential difference between metal parts that dont normally carry current ii. avoid electrical shock hazards

both i and ii

Where multiple branch circuits are to be installed and there is not an existing grounding electrode at the second building or structure _____ i. One or more grounding electrodes must be installed at the second building ii. an equipment ground must be installed with the branch circuit iii. both i and ii iiii neither i or ii

both i and ii

when grounding electrode conductors are installed in metal conduit for physical protection, the conduit must be _____ i. bonded to the service equipment enclosure ii. bonded to the grounding electrode

i and ii

IF a GEC were to be installed inside a "conduit" to protect it from physical damage, which of the following "conduits" could be used? i. schedule 80 pvc ii. EMT iii.FMC

i and ii only

Section 250.66 is used for sizing ______ i. grounding electrode conductors ii main bonding jumpers iii. equipment grounding conductors

i only

The secondary of a transformer delivers 12 volts. One of these secondary conductors must be grounded when the supply voltage to the transformer is from a ______. i. 2 pole breaker in a 277/480 volt 3 phase 4 wire panelboard ii. 2 pole breaker in a 120/208 volt 3 phase 4 wire panelboard

i only

An acceptable method for grounding a 120/208 volt 3 phase 4 wire electrical system at a seperate building or structure is to connect ____ conduit to the grounding electrode. i. the grounded ii. the grounding iii. an ungrounded

ii only

When two buildings are supplied by a common service and no separate equipment grounding conductor was run to the separate building. The exception to section 250.32(B) permits the service disconnection means for the second building to be grounded by means of the _____ from the first building, provided there is no ground fault equipment on the common service or any electrical path between the two buildings. i. ungrounded conductor ii.grounded conductor

neithe i or ii

Whcih of these box receptacle cominations requires the installation of a grounding jumper from the receptacle to the box? all boxes and conduits are metal. Separate egcs are were not installed with these circuits. i a self grounding receptacle on a switch box that is set back in the ]\heetrock wall not more than 1/4 inch where the washer remains on the receptacle mounting screw ii a receptacle on a surface mounted handy box where both washer were moved from the receptacle mounting screws

neither i or ii

NEC section 250.118 permits _____ to be used as an equipment grounding conductor.

the armor of type ac cable

Schedule 80 PVC may be used to protect a grounding electrode conductor from physical damage. T/F

true

When current passes through a conductor a magnetic field is created around the conductor. when individual circuit conductors are either in close proximity or contained in the same cable or conduit, these magnetic fields cancel each other because the currents in each conductor are not in phase with one another. T/F

true

Potential difference refers to which of the following?

voltage

Where exothermic or irreversible compression connections are used, the connections made to fireproofed structural members _____ required to be accessible. are/are not

are not

A GEC is to be installed out of the top of the service panel to the 2" main water pipe. The water pipe enters the building at 12' above the floor in the electrical/mechanical room. Where the GEC emerges from the top of the RMC at 8' aFF the GEC must be_______.

bonded to the RMC

Section 250.66 permits a copper grounding electrode conductor to be used with _____ service entrance conductors. i.copper ii.aluminum

both

When an existing two wire nongrounding type receptacle is replaced, is a lovation wher the code requires a gfci receptacle, it is permitted to be replaced by_____

gfci receptacle

When a piece of equipment is connected to the earth it meets the definition for _____.

grounded

A ______ conductor is used to connect something to ground.

grounding

If two points in a circuit have a voltage between them but are then bonded together with a conductive jumper, there is no longer i.voltage ii.a difference in potential

i and ii

In general grounding electrodes for lighting protection ______ be connected to grounding electrodes for the electric power and communication systems. should/should not

should

A 1000-ampere 3 phase 208/120 volt service in a commercial building has a single fusable main switch and is supplied with five parallel sets of 500 kcmil ungrounded conductors. The minimum size permitted for the MBJ is _____ AWG or Kcmil

350

A single nonmetallic raceway encloses conductors for three circuits rated 40, 60 and 100 amps. The size of the aluminum grounding conductor required would be _____ awg

6

A commercial service entrance is rated at 100 amperes and the service entrance conductors are size 3 AWG. An 8 ft ground rod is driven as the grounding electrode for the building. The minimum size GEC permitted to the ground rod is a _____ AWG

8

Which part of article 250 covers equipment grounding and equipment grounding conductors?

VI

The size of the bonding jumper on the supply side of the service equipment is based on the size of the _____.

supply conductor

A 120/208 volt 3 phase 4 wire service is fed with 2 parallel conduits. Each conduit contains four 250 Kcmil conductors. The minimum size GEC permitted from the 500-A service Panel HK to the main copper building water service pipe is _____ AWG.

1/0

It is not required to verify that a circuit or equipment has been deenergized as long as all of the other steps of the lockout tagout have been performed T/F

false

One of the most important goals of the multi employer worksite policy from OSHA is to ensure that

good communication occurs between the contractors working on the site

IF a GEC were to be installed inside a conduit to protect it from physical damage, which of the following conduits could be used? i. RMC ii. EMT iii. IMC

i, ii, and iii

During ground faults, electrons seek to return to i. ground ii. the source of the power

ii only

Electrical equipment enclosures are grounded to ______ i.facilitate operation of the overcurrent protective device ii. limit the voltage drop to ground

ii only

IF a GEC were to be installed inside a "conduit" to protect it from physical damage, which of the following conduits could be used? i. schedule 40 pvc ii. EMT iii. FMC

ii only

The impedance of an electrical conductor is directly proportional to length. Therefore increases the length of the EGC _____ the impedance of the ground gault reurn path.

increases

An equipment bonding jumper could be the conductor that is ______

installed with the branch circuit conductors in a conduit or a cable run

When a ground gault occurs in a circuit where the conduit couplings and connectors are loos. the opening time of the OCPD _____ affected

is

Interlocking type ---- mc cable containing an insulated egc _____ permitted to be used withing patient care areas. is/is not

is not

In general bonding requirements for the supply side of the service equipment are ______ bonding requirements on the load side.

more stringent than

When AC current passes through a circuit conductor or a connected load, it creates _____ that creates a voltage in the circuit that actually opposes the applied voltage.

pure resistance

Where installed as overhead conductors outside of a building ac systems of less than 50 volts _______ grounded i. shall be permitted to be ii. shall be iii. shall not be

shall be

In general electrical conductors are sized on the basis of ampacity. however table 250.66 uses cross sectional area in AWG or KCMIL as a basis for sizing grounding electrode conductors for ac systems. T/F

true

Several parking lot lumineers are to be installed on metal poles. The plans require that you drive a ground rod at each light standard. You will use schedule 40 pvc underground and stub up into each pole. Since you are driving aground rod at each pole, does the NEC require you to also pull in a seperate EGC with the branch circuit? Y/N

yes

Where a 2/0 awg bare copper ground ring is installed, the minimum size GEC permitted from the service panel to the ground ring is _____ awg.

/

An example of a system that is permitted but not required to be grounded is a _____ system.

240 V 3 phase 3 wire

NEC table ____ is used to size the conductor installed between the ground bar and the neutral bar in a service panel

250.102(C)(1)

The most common configuration for a grounded three phase ac distribution system is four wire center grounded. The code requirements for identification of an equipment grounding conductor are provided in Section _____

250.119

A 2000a switchgear is fed from a transformer with five parallel sets of 600 kcmil wire in five parallel conduits _____ awg or kcmil wire is the smallest GEC permitted to the main water pipe.

3/0

Section 250.138 permits all the following methods of grounding cord and plug connected equipment except for _______

a three to two prong attachment plug adapter

The term equipotential plane refers to installation in which of the following typed of building facilities?

agricultural

A grounding electrode is required at a seperate building or structure under which of the following conditions i. one grounded system feeder is installed ii.one ungrounded system feeder is installed iii. more than one branch circuit is installed

all of the above

Which types of metal covered cable assemblies are required to have their metal coverings grounded? i.ac ii.mc iii.MI

all of these

A separately derived ac system _____ with any supply circuit conductor from another system

does not share any circuit conductor

The requirements in section NEC 250.110 to ground equipment fastened in place or connected by a permanent wiring method, exempts which of the following?

double insulated equipment

The secondary of a transformer delivers 12 volts. One of these conductors must be grounded when the supply voltage to the transformer is from a _____ i. 2-pole breaker in a 277/480 volt 3 phase 4 wire panelboard ii. 1 pole breaker in a 277/490 volt 3 phase 4 wire panelboard

either i or ii

Proper equipment grounding eliminates voltage that might cause an electric shock by ______.

eliminating potential differences between metal enclosures

Metal raceways enclosing GECs are considered to be on the _____ of the service equipment.

line

A GEC to a ground rod will be installed in Schedule 80 PVC. The PVC will be connected to the panel with a pvc male adapter and will be attached to the exterior wall using 1-hole straps. The pvc will stop about a foot short of where the GEC is connected to the ground rod. Along this 1 foot section, the GEC is not subject to physical damage. Will this installation violate the NEC requirement the GEC enclosure be continuous from the panel to the electrode? Y/N

no

A set of three phase conductors are run in PVC from a 225 amp breaker and will feed a subpanel. The original plans called for 4/0 conductors. However the subpanel was relocated so thath the feeder conductors were increased to 350 kcmil. With this damage, the minimum size EGC permitted is _____ awg.

1

A 120/240 volt service is to be run to serve a 400-A main breaker Panel B. Two parallel conduits will be installed for the service. Panel B supplies 200 amps of 240 volt loads. Additionally 122 amps of 120 volt loads are on A phase. and 188 amps of 120 volt loads are connected to B phase in PB B. The b phase conductor in each of the parallel conduits will carry ___ amps.

194

Where a 2/0 awg bare copper ground ring is installed the maximum size GEC required from the service equipment to the ground ring is ____ awg. A 2 awg GEC is the minimum required size to building steel.

2/0

Bonding jumpers used on metal raceways enclosing GECs are sized according to Table _____.

250.66

An 80 amp feeder is installed to supply power from a distributiom panel to an agricultural barn. The feeder conductors are 4 awg. The EGC is required to be ____ awg or larger

4

The following conduits are installed in a single PVC conduit. 4 awg conductors fed from a 3 pole 80 a breaker 8 awg conductors fed from a 3 pole 50 a breaker 1/0 awg conductors fed from a 3-polr 300 a circuit breaker The smallest EGC permitted to be installed in the PVC is ____ awg.

4

A grounded service consists of four paralleled sets of 400 kcmil aluminum ungrounded conductors installed in a single wireway. When a single aluminum grounded conductor is installed for this service, its minimum size is ____ AWG or kcmil aluminum.

4/0

Loose connections in a circuit conductor cause arcing and in turn oxidation occurs at the connection. The circuit is connected to a single load. The voltage at the load will be _____ with the poor connection in the circuit.

Less

A common bonding grid for a permanent swimming pool is framed by connecting together with a bonding conductor, all metal parts associated with the pool. These include the metallic parts of the pool structure framing shells and mounting brackets of lighting fixtures. metal ladders and other metal in the pool. The conductor used for this bonding is _____.

Required to be solid copper not smaller than 8 awg

under conditions of maximum ground fault current flow, an effective equipment grounding system should _____. i. incorporate adequate conductance ii. not present a fire hazard

both i and ii

All NEC grounding requirements are covered in article 250. T/F

false

When a ground fault occurs in a 277 volt branch circuit the fault current must travel through the _____ to get back through the OCPD to cause it to open. The 277-volt circuit originates in a 480/277volt 3 phase 4 wire service panelboard. i. equipment grounding conductor. ii. main bonding jumper. iii. utility neutral conductor

i and ii only

A 120 volt circuit is installed in EMT without a separate EGC. The circuit originates in a 120/208 volt 3 phase 4 wire panelboard. to cause the OCPD to operate, when a ground fault occurs in the branch circuit the fault current must travel through the system or main bonding jumper. T/F

true

potential difference is a value measured in ____?

volts

A GEC to a ground rod is installed in 1/4 EMT and the EMT is connected to both the ground rod and the bare GEC. A set screw connector is installed through a 1/4 KO in the bare metal panel can and secures the EMT to the service panel. Is a bonding jumper required from the ground bar to the set screw connector? Y/N

yes

Would it ever be permitted to install a 3/0 grounding electrode conductor when the main bonding jumper was sized at 250 Kcmil? Y/N

yes

In terms of grounding, the earth is considered to represent______/

zero potentail

A 150 amp 120/208 volt 3 phase 4 wire service consists of three 1/0 AWG ungrounded conductors and one grounded conductor. The smallest grounded conductor that can be installed for this service is ____ AWG wher the neutral load is expected to be 120 amps

1

A 120/240 volt 1 phase 3 wire service is to berun to serve 400 a main breaker panel B. Two paralled conduits will be installed for the service. Each conduit will contain two 3/0 AWG conductors for the ungrounded conductors. Most of the loads are 240 volt single phase without neutrals. The smallest neutral that can be installed in each conduit is a ____ AWG.

1/0

A 120/ 240 volt 1 phase 3 wire service is to be run to serve a 400-a main breaker panel B. Two parallel conduits are run for the service. Panel B serves the following loads. 122 amps of 120 volt loads are connected to A phase, and 185 amps of 120 loads are connected to B phase. Additionally 200 amps of 240 volt loads are supplied from panel B. The A phase conductor in each of the parallel conduits will carry ___ amps.

161

Grounded conductors run in parallel are subject to the same requirements as all other paralleled conductors. The parallel requirements for grounded conductors are covered in ______.

250.24(C)(2)

A 500 KVa 480 delta to 208/120 volt, 3 phase 4 wire transformer is to be installed. - one set of secondary conductors is installed from the transformer to a 600 a main breaker panelboard. -there will be three parallel conduits to this 600 a panel. Each conduit will contain 4 each 3/0 conductors. -A second set of secondary conductors is installed from the transformer to a 300 amp MB panelboard. ONE conduit will be installed between this 300 amps panel and the transformer. THe conduit will contain 4 each 350 kcmil conductors. -you have decided to satisfy the "grounding and bonding" requirements inside each panelboard. The smallest GEC you can run to the steel structure from the 300 amp PB is ____ awg

3

The minimum size grounding electrode conductor to building for the service shown in figure 205.6 is fed with foursets of parallel 500 KCmil service entrance conductor is _____ awg or kcmil

3/0

For alternating current systems, the maximum sizes of grounding electrode conductors required are ______.

3/0 awg copper of 250 kcmil aluminum

A 120/240 volt 1 phase 3 wire branch circuit is installed underground in pvc or egc to serve receptacles and lighting in the parking attendance shack. The circuits are run from a panelboard inside the vehicle maintenance building. The shack is constructed entirely of wood and no water or gas is supplied to the shack. Are you required to drive a ground rod or install a similar ge at the shack. Y/N

NO

A 225 KVA 480 delta to 208/120 volt, 3 phase 4 wire transformer is to be installed. - one set of secondary conductors is installed from the transformer to a 400 amp MB panelboard .There will be two parallel conduits to this 400 A panel. Each conduit will contain 3 each 3/0 ungrounded conductors and one each grounded conductor. The minimum size permitted grounded conductor will be installed in each conduit. - A second set of secondary conductors is installed from the transformer to a 225A panel. One conduit will be installed between the 225 a panel and the transformer. The conduit will contain 4 each 4/0 conductors. The smallest grounded conductor you can install in each conduit to the 400 A PB is ____ AWG

1/0

A 500 KVa 480 delta to 208/120 volt, 3 phase 4 wire transformer is to be installed. - one set of secondary conductors is installed from the transformer to a 600 a main breaker panelboard. -there will be three parallel conduits to this 600 a panel. Each conduit will contain 4 each 3/0 conductors. -A second set of secondary conductors is installed from the transformer to a 300 amp MB panelboard. ONE conduit will be installed between this 300 amps panel and the transformer. THe conduit will contain 4 each 350 kcmil conductors. -you have decided to satisfy the "grounding and bonding" requirements inside each panelboard. The smallest SBJ you can install in the 600 a PB is

1/0

Three 120 volt circuits will be installed to serve receptacles that are required to be GFCI protected. The three circuits will be installed in one conduit to a j box and then mc cable will be run from there to the receptacles. These GFCI circuit breakers will be installed in a 120/208 volt 3 phase 4 wire panelboard. The fewest number of neutrals that can be installed in the conduit is ______

3

nec 250.68(C) Exception makes references to exposed interior metal water piping. For purposes of the NEC interior metal water piping is considered to be exposed when installed above a lay in ceiling. T/F

true

Which of the following are measured in ohms i. inductive reactance ii. capacitive reactance iii. counter electromotive force

i and ii only

which of the following are considered to be current carrying conductors? i.neutral conductor ii. ungrounded conductor iii. grounded conductor

i and ii only

Which of the wiring methods listed below requires that a separate equipment grounding conductor be run with the circuit conductors? i.ENT ii.Aluminum IMC iii. PVC

i and iii only

When a 480 to 120/208 3 phase 4 wire transformer feeds a main breaker panelboard, the neutral is permitted to be connected to the grounding electrode conductor and the equipment grounding conductors ________ i. in the transformer enclosure ii in the panel iii either i or ii

iii

Total opposition to the flow of electric current is called resistance in a dc circuit and _____ in an ac circuit.

impedance

When _____ are installed in a conduit from one building to a 2nd building the NEC requies that one or more grounding electrodes be installed. THere is not an existing grounding electrode at the 2nd building.The circuits originate from a 120/208 volt, 3 phase 4 wire panel in the main building and include an EGC in the conduit. i two hots(for 208) plus one hot with a neutral for 120 loads ii. three hots and one neutral these serve only 120 loads

i only

A 750 KVA 480 delta to 208/120 volt 3 phase 4 wire transformer is to be installed. You have decided to "ground and bond" everything in the transformer enclosure - one set of secondary conductors is installed from the transformer to a 600 amp maind breaker panelboard. ther will be two parallel conduits to this 600 a panel. Each conduit will contain 4 each 350 kcmil conductors. - a second set of secondary conductors is installed from the transfrormer to a 225 a MB panelboard one conduit will be installed between this 225 amp panel and the transformer. The conduit will contain 4 each 4/0 conductors. -A third set of secondary conductors is installed between the transformer to an 800 amp safety switch fused at 800 amps. threee parallel conduits will be installed between the transformer and the switch. There will be four each 300 kcmil conductors installed in each of the three conduits. - A fourth set will be installed from the transformer to a 400 amp panelboard that contains a 400 amp main. There will be two parallel conduits to this 350 amp MB panel. Each conduit will contain 4 each 3/0 conductors. The smallest bonding jumper you can install from the ground bar to XO in the transformer is ____ AWG or kcmil

300

Which of the following is not permitted to serve as an equipment grounding conductor?

a metallic water piping system

Which of the following GECs is always required to be protected, by installing it inside RMC or equivalent means of protection, whether or not it is subject to physical damage. i. 6 awg ii. 4 awg iii. 8 awg

iii only

A solidly grounded system is one where one of the current carrying conductors is intentionally connected to the earth. T/F

true

Although air is a good insulator, ionized air is conductive and helps to sustain arcs when an electrical are causes the air to be ionized. T/F

true

Grounding conductor is an NEC definition that generally covers many different concepts and parts of a grounding system. T/F

true

A 225 KVA, 480 delta to a 208/120 volt 3 phase 4 wire transformer is to be installed. - One set of secondary conductors is installed from the transformer to an 400 a MB panelboard. There will be two parallel conduits to this 400 a panel. Each conduit will contain 4 each 3/0 conductors. - A second set of secondary conductors is installed from the transformer to a 225 MB PB. Ome conduit will be installed between this 225 A panel and the transformer. The conduit will contain 3 each 4/0 ungrounded conductors and the smallest permitted grounded conductor. Almost all the loads are connected to 3 phase.

2

Where a 2/0 awg bare copper ground ring is installed, the minimum size GEC permitted from the service equipment ground ring is ____ awg. 4/0 awg gec is the minimum required to building steel.

2/0

A 500 KVA 480 delta to 208/120 3 phase 4 wire transformer is to be installed. You have to decide to " ground and bond" everything in the transformer enclosure. -One set of secondary conductors is installed from the transformer to a 400 A main breaker panelboard. There will betwo parallel conduits to this 400 a panel. Each conduit will contain 4 each 3/0 conductors. -A second set of secondary conductors is installed from the transformer to a 225 A MB PB. One conduit will be installed between this 225 amps panel and the transformer. The conduit will contain 4 each 4/0 conductors. -A third set of secondary conductors is installed from the transformer to a 600 amp safety switch fused at 500 amps. Three parallel conduits will be installed between the transformer and the switch. There will be four each 2/0 conductors installed in each of the three conduits. -A fourth set will be installed from the transformer to a400 a panelboard that contains a 300 a main. There will be two parallel conduits to this 300 amp MB. Each conduit will contain 4 each 1/0 conductors. From the transformer , the smallest GEC you can run to the steel structure is _______

3/0

A 500 KVA 480 delta to 208/120 3 phase 4 wire transformer is to be installed. You have to decide to " ground and bond" everything in the transformer enclosure. -One set of secondary conductors is installed from the transformer to a 400 A main breaker panelboard. There will betwo parallel conduits to this 400 a panel. Each conduit will contain 4 each 3/0 conductors. -A second set of secondary conductors is installed from the transformer to a 225 A MB PB. One conduit will be installed between this 225 amps panel and the transformer. The conduit will contain 4 each 4/0 conductors. -A third set of secondary conductors is installed from the transformer to a 600 amp safety switch fused at 500 amps. Three parallel conduits will be installed between the transformer and the switch. There will be four each 2/0 conductors installed in each of the three conduits. -A fourth set will be installed from the transformer to a400 a panelboard that contains a 300 a main. There will be two parallel conduits to this 300 amp MB. Each conduit will contain 4 each 1/0 conductors. The smallest bonding jumper you can install between xp and thr ground bar attached to the transformer enclosure is ______.

3/0