Article 240 -Overcurrent Protection

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

HID

_____ shall not be located over the steps of a stairway.

Overcurrent devices

Molded-case circuit breakers ____________ to be reconditioned.

are NOT permitted

Supplementary overcurrent devices used in luminaires or appliances _________ to be readily accessible.

are not required

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

are permitted

Outside feeder tap conductors can be of unlimited length without overcurrent protection at the point they receive their supply if the tap conductors _____.

are protected from physical damage, terminate at a single circuit breaker or a single set of fuses that limits the load to the ampacity of the tap conductors, and the overcurrent device is part of the building feeder disconnect

Plug fuses of the Edison-base type shall be used only _____.

as a replacement in existing installations

Single-pole breakers with identified handle ties __________ to protect each ungrounded conductor for line-to-line connected loads.

can be used

Conductor overload protection shall not be required where the interruption of the _____ would create a hazard, such as in a material-handling magnet circuit or fire pump circuit. However, short-circuit protection is required.

circuit

Overcurrent devices are not permitted to be located in the bathrooms of _____.

dwelling units, dormitories, and guest rooms or guest suites of hotels or motels

Supplementary overcurrent protection _____.

may be used to protect internal circuits of equipment

Overcurrent protection shall not exceed _____.

15A for 14 AWG copper, 20A for 12 AWG copper, and 30A for 10 AWG copper

The general requirements for overcurrent protection and overcurrent protective devices not more than 1,000V, nominal are provided in Article _____.

240

Reconditioned circuit breakers shall be listed as "reconditioned" and the original listing mark shall be _____.

removed

Circuit breakers used to switch 120V and 277V fluorescent lighting circuits shall be listed and marked _____.

SWD or HID

The arc energy reduction protection system shall be performance tested when first installed by _____ in accordance with the manufacturer.

a qualified person(s)

Fuses shall be marked with their _____.

ampere and voltage rating, interrupting rating where other than 10,000A, and name or trademark of the manufacturer

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

located behind bolted equipment enclosure doors, located behind locked doors accessible only to qualified personnel, and password protected, with password accessible only to qualified personnel

Where the circuit breaker handles are operated vertically, the "up" position of the handle shall be the "_____" position.

on

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

open

Overcurrent protection for conductors and equipment is provided to _____ the circuit if the current reaches a value that will cause an excessive or dangerous temperature in conductors or conductor insulation.

open

Overcurrent devices shall not be located _____.

where exposed to physical damage, near easily ignitible materials, such as in clothes closets, and in bathrooms of dwelling units

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

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.

1,000A

The standard ampere ratings for fuses include(s) _____.

1A, 6A, and 601A

Plug fuses of the Edison-base type shall have a maximum rating of _____.

30A

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 device that, when interrupting currents in its current-limiting range, reduces the current flowing in the faulted circuit to a magnitude substantially less than that obtainable in the same circuit if the device were replaced with a solid conductor having comparable impedance, is a(an) "_____ protective device."

current-limiting overcurrent

A circuit breaker with a slash rating, such as 120/240V or 480Y/277V, shall be permitted to be applied in a solidly grounded circuit where the nominal voltage of any conductor to ground _____ the lower of the two values of the circuit breaker's voltage rating and the nominal voltage between any two conductors _____ the higher value of the circuit breaker's voltage rating.

does not exceed

Circuit breaker enclosures shall be permitted to be installed _____ where the circuit breaker is installed in accordance with 240.81

horizontally

A conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the ampacity permitted for similar conductors is known as a _____.

tap conductor

Only _____ circuit breakers shall be permitted to be reconditioned.

low-voltage power, medium-voltage power, and high-voltage

If the circuit\'s overcurrent device exceeds _____, the conductor ampacity shall have a rating not less than the rating of the overcurrent device.

800A

A circuit breaker having an interrupting current rating of other than _____ shall have its interrupting rating marked on the circuit breaker.

5,000A

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

Where a method to reduce clearing time for fuses rated 1,200A or greater is required in accordance with 240.67(B), the _____ reduction system shall be performance tested when first installed on site.

arc energy

The next higher standard rating overcurrent device above the ampacity of the ungrounded conductors being protected shall be permitted to be used, provided the _____.

conductors being protected are not part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads, ampacity of the conductors does not correspond with the standard ampere rating of a fuse or circuit breaker, and next higher standard rating selected does not exceed 800A

Fuseholders for cartridge fuses shall be so designed that it is difficult to put a fuse of any given class into a fuseholder that is designed for a _____ lower or a _____ higher than that of the class to which the fuse belongs.

current, voltage

Circuit breakers and switches containing fuses shall be readily accessible and installed so the center of the grip of the operating handle of the switch or circuit breaker, when in its highest position, is not more than _____ above the floor or working platform.

6 ft 7 in.

Tap conductors not over 25 ft in length shall be permitted, providing the _____.

ampacity of the tap conductors is not less than one-third the rating of the overcurrent device protecting the feeder conductors being tapped, tap conductors terminate in a single circuit breaker or set of fuses that limits the load to the ampacity of the tap conductors, and tap conductors are suitably protected from physical damage

Conductors supplied under the tap rules ________________ another conductor using the tap rules.

are NOT allowed to supply

Outside secondary conductors can be of unlimited length without overcurrent protection at the point they receive their supply if the conductors _____.

are protected from physical damage, terminate at a single overcurrent device equal to or less than their ampacity, and the overcurrent device is part of the building disconnect

A circuit breaker with a _____ rating, such as 120/240V or 277/480V can be used on a solidly grounded circuit where the nominal voltage of any conductor to ground does not exceed the lower of the two values, and the nominal voltage between any two conductors does not exceed the higher value.

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