Exam 17: Overcurrent Protection: Fuses and Circuit Breakers

and the National Electrical Manufacturers Association establish standards for the ratings, types, classifications, and testing procedures for fuses and circuit breakers.

Free

(Multiple Choice)

4.9/5

(37)

Question 1

Correct Answer:

Verified

circuit breakers are the most common type in use today.

Free

(Multiple Choice)

4.9/5

(36)

Question 2

Correct Answer:

Verified

Describe the class of fuses that is used for control circuit protection.

Free

(Essay)

4.8/5

(37)

Question 3

Correct Answer:

Verified

Class CC fuses are primarily used for control-circuit protection, for the protection of motor control circuits, ballasts, small transformers, and so on.They are UL listed as branch-circuit fuses.Class CC fuses are rated at 600 volts or less and have a 200,000-ampere interrupting rating in sizes from
1/10 ampere through 30 amperes.These fuses measure 1-1/2 in.x 13/32 in.(38.1 mm x 10.3 mm) and can be recognized by a button on one end of the fuse.This button is unique to Class CC fuses.When a fuseblock or fuseholder that has the matching Class CC rejection feature is installed, it is impossible to insert any other 1-1/2 in.x 13/32 in.(38.1 mm x 10.3 mm) fuse.Only a Class CC
fuse will fit intothese special fuseblocks and fuseholders.A Class CC fuse can be installed in a standard fuseholder.

In the case of a delta, 3phase, cornergrounded "B" phase system, a device called a can be installed in the "B" phase.

(Multiple Choice)

4.8/5

(35)

Question 4

Class fuses formerly were called NEC or Code fuses.

(Multiple Choice)

4.9/5

(29)

Question 5

For motor branch circuits, the maximum setting of a conventional inverse-time circuit breaker must not exceed percent of the full-load current of the motor.

(Multiple Choice)

4.8/5

(32)

Question 6

An interrupting rating is a(n) rating, which is a measure of the fuse's or circuit breaker's ability to safely open an electrical circuit under fault conditions, such as an overload, short circuit, or ground fault.

(Multiple Choice)

4.8/5

(32)

Question 7

When compared to other types of fuses, the fuse has the lowest energy let-through values.

(Multiple Choice)

4.8/5

(33)

Question 8

A dual-element, time-delay fuse has one or more fusible elements (links) connected .

(Multiple Choice)

4.7/5

(39)

Question 9

Fused switches are available in ratings of up to amperes in both 250 and 600 volts.

(Multiple Choice)

4.8/5

(39)

Question 10

What are peak let-through charts used for?

(Essay)

4.9/5

(32)

Question 11

When you remove a fuse from a switch, and then take a resistance reading across the fuse using a(n) , a good fuse will show zero or a very minimal resistance.

(Multiple Choice)

4.8/5

(28)

Question 12

What are some prohibitions on the location of overcurrent devices?

(Essay)

4.8/5

(35)

Question 13

Series-rated equipment is also referred to as .

(Multiple Choice)

4.9/5

(40)

Question 14

The terms interrupting rating and are used interchangeably in the electrical industry, but there is a subtle difference.

(Multiple Choice)

4.8/5

(37)

Question 15

Low-voltage power circuit breakers are listed under UL Standard .

(Multiple Choice)

4.8/5

(40)

Question 16

Conventional plug fuses have a base referred to as a(n) base.This base is of the same shape as the base on a light bulb.

(Multiple Choice)

5.0/5

(30)

Question 17

The Class fuse is a nonrenewable cartridge type and has a minimum interrupting rating of 200,000 RMS symmetrical amperes.

(Multiple Choice)

4.8/5

(37)

Question 18

What is the mechanism through which thermal-magnetic circuit breakers work?

(Essay)

4.9/5

(33)

Question 19

What are the factors influencing speed of response of an overcurrent device?

(Essay)

4.7/5

(37)

Question 20

Showing 1 - 20 of 20

Exam 17: Overcurrent Protection: Fuses and Circuit Breakers

and the National Electrical Manufacturers Association establish standards for the ratings, types, classifications, and testing procedures for fuses and circuit breakers.

circuit breakers are the most common type in use today.

Describe the class of fuses that is used for control circuit protection.

In the case of a delta, 3­phase, corner­grounded "B" phase system, a device called a can be installed in the "B" phase.

Class fuses formerly were called NEC or Code fuses.

For motor branch circuits, the maximum setting of a conventional inverse-time circuit breaker must not exceed percent of the full-load current of the motor.

An interrupting rating is a(n) rating, which is a measure of the fuse's or circuit breaker's ability to safely open an electrical circuit under fault conditions, such as an overload, short circuit, or ground fault.

When compared to other types of fuses, the fuse has the lowest energy let-through values.

A dual-element, time-delay fuse has one or more fusible elements (links) connected .

Fused switches are available in ratings of up to amperes in both 250 and 600 volts.

What are peak let-through charts used for?

When you remove a fuse from a switch, and then take a resistance reading across the fuse using a(n) , a good fuse will show zero or a very minimal resistance.

What are some prohibitions on the location of overcurrent devices?

Series-rated equipment is also referred to as .

The terms interrupting rating and are used interchangeably in the electrical industry, but there is a subtle difference.

Low-voltage power circuit breakers are listed under UL Standard .

Conventional plug fuses have a base referred to as a(n) base.This base is of the same shape as the base on a light bulb.

The Class fuse is a nonrenewable cartridge type and has a minimum interrupting rating of 200,000 RMS symmetrical amperes.

What is the mechanism through which thermal-magnetic circuit breakers work?

What are the factors influencing speed of response of an overcurrent device?

Commercial Building Plans and Specifications

Reading Electrical Working Drawings- Entry Level

Calculating the Electrical Load

Branch Circuits

Switches and Receptacles

Wiring Methods

Motor and Appliance Circuits

Feeders

Special Systems

Working Drawings- Upper Level

Special Circuits Owners Circuits

Panelboard Selection and Installation

The Electric Service

Lamps and Ballasts for Lighting

Luminaires

Emergency, Legally Required Sstandby, and Optional Standby Power Systems

Short-Circuit Calculations and Coordination of Overcurrent Protective Devices

Equipment and Conductor Short-Circuit Protection

Low-Voltage Remote-Control

The Cooling System

Commercial Utility Interactive Photovoltaic Systems

Filters

In the case of a delta, 3phase, cornergrounded "B" phase system, a device called a can be installed in the "B" phase.