Podcast
Questions and Answers
A circuit breaker trips automatically when there is an ______.
A circuit breaker trips automatically when there is an ______.
overcurrent
Silver and copper are examples of good electrical ______.
Silver and copper are examples of good electrical ______.
conductors
One major advantage of a fuse is its reliability and ______.
One major advantage of a fuse is its reliability and ______.
stability
Materials like rubber and glass are classified as ______.
Materials like rubber and glass are classified as ______.
Signup and view all the answers
Single-throw knife switches must be installed so that gravity does not tend to ______ them.
Single-throw knife switches must be installed so that gravity does not tend to ______ them.
Signup and view all the answers
Wires are electrical conductors which are 8 mm2 (AWG no. 8) or ______.
Wires are electrical conductors which are 8 mm2 (AWG no. 8) or ______.
Signup and view all the answers
Stranded wire consists of a group of wires twisted together to form a metallic ______.
Stranded wire consists of a group of wires twisted together to form a metallic ______.
Signup and view all the answers
Double-throw knife switches can be mounted with the throw oriented either ______ or horizontal.
Double-throw knife switches can be mounted with the throw oriented either ______ or horizontal.
Signup and view all the answers
Service entrance conductors subjected to physical damage shall be protected by ______.
Service entrance conductors subjected to physical damage shall be protected by ______.
Signup and view all the answers
The service disconnecting means shall consist of no more than ______ switches or circuit breakers.
The service disconnecting means shall consist of no more than ______ switches or circuit breakers.
Signup and view all the answers
For a one family dwelling, the service disconnecting means should have a rating of ______ where the initial computed load is 10 kVA or more.
For a one family dwelling, the service disconnecting means should have a rating of ______ where the initial computed load is 10 kVA or more.
Signup and view all the answers
Electrical Metallic Tubing (EMT) is a type of ______ used for service entrance conductors.
Electrical Metallic Tubing (EMT) is a type of ______ used for service entrance conductors.
Signup and view all the answers
The type of wiring method used for service entrance conductors must comply with the applicable ______.
The type of wiring method used for service entrance conductors must comply with the applicable ______.
Signup and view all the answers
In a two circuit installation, the service disconnecting means shall have a rating of not less than ______ amperes.
In a two circuit installation, the service disconnecting means shall have a rating of not less than ______ amperes.
Signup and view all the answers
Type MC cables are used as an approved means of ______ for service conductors.
Type MC cables are used as an approved means of ______ for service conductors.
Signup and view all the answers
Service entrance conductors can be installed in methods such as Open-wiring on insulators or ______ tubing.
Service entrance conductors can be installed in methods such as Open-wiring on insulators or ______ tubing.
Signup and view all the answers
A circuit breaker serves as both an ______ protective device and a switch.
A circuit breaker serves as both an ______ protective device and a switch.
Signup and view all the answers
A ______ is an overcurrent protective device that uses a fusible element to open the circuit.
A ______ is an overcurrent protective device that uses a fusible element to open the circuit.
Signup and view all the answers
Ampacity refers to the ______-carrying capacity of an electric conductor.
Ampacity refers to the ______-carrying capacity of an electric conductor.
Signup and view all the answers
The panelboard should be installed near the ______ center for optimal wiring efficiency.
The panelboard should be installed near the ______ center for optimal wiring efficiency.
Signup and view all the answers
A branch circuit consists of circuit conductors between the final overcurrent device and the ______.
A branch circuit consists of circuit conductors between the final overcurrent device and the ______.
Signup and view all the answers
An overcurrent can be caused by equipment ______, short circuits, or ground faults.
An overcurrent can be caused by equipment ______, short circuits, or ground faults.
Signup and view all the answers
Conductors must be protected against overcurrent according to their ______.
Conductors must be protected against overcurrent according to their ______.
Signup and view all the answers
The panelboard is designed to be accessible only from the ______ side.
The panelboard is designed to be accessible only from the ______ side.
Signup and view all the answers
Study Notes
Circuit Breakers vs. Fuses
- Circuit breakers trip automatically during overcurrent situations and can be reset after correcting the fault, while fuses must be replaced once blown.
- Fuses are known for their reliability and stability, requiring minimal maintenance compared to circuit breakers, which need periodic testing.
- Cost-wise, fuses are typically less expensive than circuit breakers.
Standard Ampere Ratings
- Standard Ampere ratings for fuses and inverse time circuit breakers range from 15 to 6000 Amperes in various increments.
Installation Guide for Knife Switches
- Single-throw Knife Switches: Must be positioned to prevent gravity from closing them. Inverted models require a locking device.
- Double-throw Knife Switches: Allowed to be mounted vertically or horizontally, with locking devices needed for vertical configurations.
Electrical Conductors and Insulators
- Conductors: Materials with low resistance to current. Examples include silver, copper, aluminum, and iron.
- Insulators: Materials with high resistance to current. Notable examples are rubber, porcelain, glass, and dry air.
Wires and Cables
- Wires are defined as conductors smaller than 8 mm² (AWG no. 8), while cables are larger, available in solid or stranded forms.
- For limited loads on single branch circuits, recommended sizes are 3.5 mm² for copper and 5.5 mm² for aluminum or copper-clad aluminum.
Service Entrance Conductors Installation
- Must comply with applicable codes using methods such as Rigid Metal Conduit (RMC), Electrical Metallic Tubing (EMT), or Service-Entrance Cables.
Protection for Service Entrance Conductors
- Protection methods include RMC, IMC, EMT, or approved cable types to safeguard against physical damage.
Service Disconnecting Means
- A service disconnecting mechanism is mandatory to isolate all conductors in a building from service-entrance conductors.
- Up to six switches or circuit breakers can be mounted in a single enclosure for ease of access.
- Must have adequate ratings based on load requirements, with specifics like 15 A for single circuit installations.
Panelboards
- Constructed to house buses, protective devices, and control switches, panelboards must be conveniently located, typically near heavy load areas like kitchens and laundry rooms.
Branch Circuit Protection
- Overcurrent is defined as any current exceeding the rated capacity, caused by overloads or short circuits.
- Conductors must be protected against overcurrent as per their ampacities.
Functions of Circuit Breakers and Fuses
- Circuit breakers serve dual purposes: acting as switches and overcurrent protection devices equipped with auto-tripping features.
- Fuses function by employing a fusible element that opens the circuit during overcurrent, making them one of the most common protective devices.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz explores the fundamental differences between circuit breakers and fuses. Understand the advantages and disadvantages of each system, with a focus on reliability, maintenance, and operational safety.