UNEC 240-250

Réussis tes devoirs et examens dès maintenant avec Quizwiz!

When taps are not over 10 ft in length for field installations, and they leave the enclosure or vault in which the tap is made, the ampacity of the tap conductors cannot be less than _____ the rating of the device protecting the feeder.

1/10

One or more metal in-ground support structure(s) in direct contact with the earth vertically for _____ ft or more, with or without concrete encasement is permitted to be a grounding electrode in accordance with 250.52.

10

Ground-fault protection of equipment shall be provided for solidly grounded wye electrical systems of more than 150 volts-to-ground, but not exceeding 1,000V phase-to-phase for each individual device used as a building or structure main disconnecting means rated _____ or more, unless specifically exempted.

1000A

The common grounding electrode conductor installed for multiple separately derived systems shall be permitted to be the metal structural frame of the building or structure that complies with 250.68(C)(2) or is connected to the grounding electrode system by a conductor not smaller than _____.

3/0 AWG copper or 250 kcmil aluminum

Grounding electrode conductors _____ AWG and larger that are not exposed to physical damage can be run along the surface of the building construction without metal covering or protection.

6

Circuit breakers used to switch high-intensity discharge lighting circuits shall be listed and marked as _____.

HID

A Type 2 surge protective device is permitted to be connected on either the line or load side of the service equipment.

false

Type 2 surge protective device(s) shall be connected on the load side of the _____ in a separately derived system.

first overcurrent device

A circuit breaker with a _____ voltage rating, such as 240V or 480V, can be used where the nominal voltage between any two conductors does not exceed the circuit breaker voltage rating.

straight

Feeder taps are permitted to be located at any point on the load side of the feeder overcurrent protective device.

true

Surge protective devices shall be listed.

true

Surge protective devices shall be marked with a short-circuit current rating and shall not be installed where the available fault current is in excess of that rating.

true

The supply-side bonding jumper on the supply side of services shall be sized according to the _____.

ungrounded supply conductor size

Where not routed with circuit conductors as permitted in 250.130(C) and 250.134(A) Exception No. 2, equipment grounding conductors smaller than _____ shall be protected from physical damage by an identified raceway or cable armor.

6AWG

A rod or pipe electrode shall be installed such that at least _____ of length is in contact with the soil.

8ft

For grounded systems, electrical equipment and other electrically conductive material likely to become energized shall be installed in a manner that creates a _____ from any point on the wiring system where a ground fault may occur to the electrical supply source.

all of these

Only _____ circuit breakers shall be permitted to be reconditioned.

all of these

For adjustable-trip circuit breakers, restricted access is defined as _____.

any of these

Tap connections to a common grounding electrode conductor for multiple separately derived systems shall be made at an accessible location by _____.

any of these

Cartridge fuses in circuits of _____, and all fuses in circuits over 150 volts to ground, shall be provided with a disconnecting means on their supply side so that each circuit containing fuses can be independently disconnected from the source of power.

any voltage

A separate bonding jumper to the building structural metal shall not be required if the metal frame of a building or structure is used as the _____ for the separately derived system.

grounding electrode

The conductors used to connect the surge protective device to the line or bus and to ground shall not be any longer than _____ and shall avoid unnecessary bends.

necessary

For the continuity of equipment grounding conductors and attachment in boxes, a connection used for _____ shall be made between the metal box and the equipment grounding conductor(s) in accordance with 250.8.

no other purpose

Circuit breakers shall _____ all ungrounded conductors of the circuit both manually and automatically unless specifically permitted otherwise.

open

Supplementary overcurrent devices used in luminaires or appliances are not required to be readily accessible.

true


Ensembles d'études connexes

Management of Patients with Immunodeficiency Disorders

View Set

chapter 25 intro to the health care

View Set

NUR 238 PrepU Chapter 1: Perspectives on Maternal and Child Health Care

View Set

Chapter 10: Reporting Requirements under the 1934 Securities Exchange Act - Multiple Choice

View Set

B9: Brown v. Board 1954 and Little Rock, role of eisenhower

View Set

DEVELOPMENTAL FINAL PART 1 CONT.-CHAPTER 18

View Set