ch 5 Flashcards
The ? is/are defined as the conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.
service
Where a system is grounded, the service must be supplied with a(n) ? conductor.
grounded
What is the minimum-size aluminum main bonding jumper (wire-type) for a service if the largest ungrounded service conductor is 500 (kcmil) copper?
1/0 AWG
The grounded conductor of a service must always be a neutral conductor.
false
Where the utility transformer supplying a service is located outside the building, a grounding connection is not required to be made outside a building or structure served by a grounded electrical service.
false
A grounding electrode connection is required to be made at a(n) ? location anywhere from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral up to and including the terminal or bus to which the grounded conductor is connected in the service disconnecting means.
accessible
A meter socket enclosure sealed by the utility makes the enclosure inaccessible, by definition.
false
Which of the following is not one of the four conductors in the grounding and bonding scheme for a service supplied by a grounded system?
System bonding jumper
Where a service is supplied by an ungrounded system, the grounded conductor is required to be routed to the service disconnecting means enclosure and bonded to it.
false
Where a service is supplied by a grounded system, the grounded conductor is required to be routed to the service disconnecting means enclosure and bonded to it.
true
The grounded conductor is required to be routed to the service equipment along with its associated ungrounded service conductors.
true
The main bonding jumper in a service disconnecting means enclosure can be in which of the following forms?
Bus
Green screw
Wire
If a service disconnecting means is made up of six disconnects in separate enclosures, how many main bonding jumpers will be required for the service?
6
Where the service disconnecting means is made up of two to six disconnects in a single listed service equipment assembly, how many main bonding jumpers are required within the listed assembly?
1
If a main bonding jumper is a wire type, what NEC table is used to size it?
Table 250.102(C)(1)
The grounded neutral conductor serves which two purposes for a grounded service?
Carries the maximum unbalanced return neutral load
Serves as an effective ground-fault current path in gro
If a main bonding jumper is a screw, the screw is always required to be identified using the color green.
true
The ? is a conductor connected to the neutral point of a system that is intended to carry current under normal conditions.
neutral conductor
For a grounded service, the ? is the intentionally constructed, low-impedance, effective ground-fault current path addressed in 250.4(A).
grounded conductor
If the ungrounded service conductors are 600 kcmil copper, what is the minimum size required for the grounded conductor supplying the same service?
1/0 AWG
Where a service is supplied from a corner-grounded system, and the ungrounded conductors are sized at 750 kcmil copper, what is the minimum size required for the grounded conductor?
750 kcmil copper
Where a grounded service is supplied using two 500 kcmil copper conductors in parallel (in two separate raceways) for each ungrounded service conductor, what is the minimum size required for the grounded conductor in each raceway supplying the service?
1/0 AWG
Which of the following characteristics are required for ungrounded conductors installed in parallel?
Must be not smaller than 1/0 AWG (generally)
Must be the same conductor material
Must be the same insulation type
Must be the same length
Same size
Terminated the same
Grounding connections to the grounded conductor are generally not permitted on the load side of the service equipment enclosure.
true
A grounded conductor (often the neutral) larger than 6 AWG is required to be identified by which of the following methods?
A bare conductor that is part of a listed service-entrance cable assembly
A continuous white or gray outer finish
A distinctive white or gray marking at terminations that encircles the conductor
Three continuous white or gray stripes along its entire length on other than green insulation
The service disconnecting means used for a grounded supply system is required to be listed as suitable for use as service equipment.
true
Service equipment that is listed as suitable for use only as service equipment always includes a main bonding jumper.
false
The NEC requires that a(n) ? be provided in the grounded conductor for service equipment.
disconnecting means
If a service switchboard is supplied from an ungrounded 240-volt system, which of the following markings are required on the switchboard?
Caution: Ungrounded System Operating 240 Volts Between Conductors
The NEC generally requires all metal enclosures and raceways for service conductors to be grounded except for metal components such as metal elbows in a run of nonmetallic service raceway that are isolated from contact by persons by not less than ? of cover to any part of the elbow.
18 inches
Ground detectors are required to be installed on services supplied by ungrounded systems, and the ground detection sensing equipment must be connected as close as practicable to the service or source.
true
If the size of the largest ungrounded service conductor for a service is 3,600 kcmil (six 600 kcmil conductors in parallel per phase), what is the minimum-size copper wire-type main bonding jumper required?
500 kcmil copper
Note: Review sizing methods for the 12.5% rule when the size of the largest ungrounded service conductor exceeds the values in Table 250.102(C)(1). Use of Table 8, Chapter 9 should be reviewed.
3600 x 12.5% = 450 kcmil
Take that value to Table 8 in the left column and find that the minimum kcmil required is 450 (larger than 400 kcmil), then round up to 500 kcmil copper.
The correct answer is: 500 kcmil copper
Referring to the drawing, what is the minimum size required for a copper wire-type main bonding jumper for this service?
2 awg
What is the minimum size required for a copper grounded conductor of a 3-phase, 3-wire, corner grounding delta system if the ungrounded phase conductors are sized at 500 kcmil copper?
500 kcmil
Note: Refer to Section 250.24(C)(3) to confirm the answer. The grounded conductor of this system must be not less that the size of the ungrounded conductors of this system.
The correct answer is: 500 kcmil
Because in-ground swimming pools provide an excellent grounding connection to the Earth, when they are installed on a property, they are required to be included in, and bonded to, the grounding electrode system installed for a building or structure served.
false
Where the utility transformer supplying the service is located outside the building or structure served, at least one additional grounding connection shall be made from the grounded service conductor to a grounding electrode at which of the following locations?
At the transformer
Elsewhere outside the building
