CBI Electrical Systems Inspection — Questions and Answers
Question 1: What is the purpose of a GFCI (Ground Fault Circuit Interrupter) outlet?
- To rapidly shut off power when it detects current flowing through an unintended path (ground fault), preventing electrocution (Correct answer)
- To prevent power surges from damaging appliances
- To increase the voltage available at the outlet
- To reduce electricity consumption
Correct answer: To rapidly shut off power when it detects current flowing through an unintended path (ground fault), preventing electrocution
GFCIs monitor the balance between hot and neutral conductors. When current leaks to ground (through a person or water), the GFCI detects the imbalance (as little as 5 milliamps) and trips in 1/40th of a second.
Question 2: Where are GFCI outlets required in residential construction?
- Bathrooms, kitchens (within 6 feet of sink), garages, outdoors, basements, crawl spaces, and laundry areas (Correct answer)
- Only in bathrooms
- Only outdoors
- GFCIs are optional in residential construction
Correct answer: Bathrooms, kitchens (within 6 feet of sink), garages, outdoors, basements, crawl spaces, and laundry areas
The NEC requires GFCI protection anywhere water and electricity may come into contact: bathrooms, kitchens near sinks, garages, outdoor receptacles, unfinished basements, crawl spaces, and laundry areas.
Question 3: What is the National Electrical Code (NEC)?
- The standard for safe electrical installation adopted by most US jurisdictions as part of their building codes (Correct answer)
- A federal law enforced by the FBI
- A voluntary guideline with no enforcement
- A code that applies only to commercial buildings
Correct answer: The standard for safe electrical installation adopted by most US jurisdictions as part of their building codes
The NEC (NFPA 70) is the most widely adopted electrical code in the US, setting requirements for electrical installation practices, wiring methods, equipment, and systems to protect people and property from electrical hazards.
Question 4: What is the minimum service size for a new single-family home?
- 200 amperes (Correct answer)
- 60 amperes
- 100 amperes
- 400 amperes
Correct answer: 200 amperes
While 100A was once common, most jurisdictions now require a minimum 200A service for new single-family homes to accommodate modern electrical loads including HVAC systems, appliances, and electric vehicle charging.
Question 5: What is an arc-fault circuit interrupter (AFCI)?
- A device that detects dangerous electrical arcing and disconnects the circuit to prevent fires (Correct answer)
- A type of surge protector
- A circuit breaker that only trips during lightning strikes
- A GFCI with a different name
Correct answer: A device that detects dangerous electrical arcing and disconnects the circuit to prevent fires
AFCIs detect hazardous arcing conditions (damaged wires, loose connections) that can ignite surrounding materials. The NEC requires AFCI protection in bedrooms, living rooms, and most other habitable areas.
Question 6: What is the maximum distance between receptacle outlets along a wall in a habitable room?
- 12 feet (so no point along a wall is more than 6 feet from an outlet) (Correct answer)
- 4 feet
- 20 feet
- There is no maximum distance requirement
Correct answer: 12 feet (so no point along a wall is more than 6 feet from an outlet)
The NEC 6-12 rule requires outlets so that no point along any wall is more than 6 feet from a receptacle, meaning outlets must be no more than 12 feet apart, reducing the need for extension cords.
CBI Electrical Systems Inspection
What is the purpose of a GFCI (Ground Fault Circuit Interrupter) outlet?