CBI Electrical Systems Inspection 2 — Questions and Answers
Question 1: What is proper grounding and why is it essential in electrical systems?
- Connecting electrical systems to earth ground to provide a safe path for fault currents and prevent shock hazards (Correct answer)
- Burying electrical wires underground
- Painting conduit green
- Attaching wires to the floor
Correct answer: Connecting electrical systems to earth ground to provide a safe path for fault currents and prevent shock hazards
Grounding provides a low-resistance path for fault currents to flow to earth, allowing overcurrent devices (breakers/fuses) to trip quickly during a ground fault, preventing electrical shock and fire.
Question 2: What is the difference between a 15-amp and 20-amp circuit?
- A 20-amp circuit uses 12-gauge wire and handles higher loads; a 15-amp circuit uses 14-gauge wire for lighter loads (Correct answer)
- They are identical except for the breaker size
- 20-amp circuits are only for industrial use
- 15-amp circuits carry more power
Correct answer: A 20-amp circuit uses 12-gauge wire and handles higher loads; a 15-amp circuit uses 14-gauge wire for lighter loads
20-amp circuits require larger 12 AWG wire and are used for kitchen, bathroom, and garage outlets. 15-amp circuits use 14 AWG wire for general-purpose outlets and lighting in most rooms.
Question 3: What is the purpose of a main electrical panel inspection?
- To verify proper installation, correct breaker sizing, appropriate wire connections, grounding, and safe clearances (Correct answer)
- To check if the panel door closes properly
- To count the number of circuits
- To verify the electricity bill is correct
Correct answer: To verify proper installation, correct breaker sizing, appropriate wire connections, grounding, and safe clearances
Panel inspections verify proper bus connections, correct breaker-to-wire sizing, secure connections, bonding and grounding, working clearances (30 inches front, 36 inches wide), labeling, and absence of double-tapped breakers.
Question 4: What is a tamper-resistant receptacle and where is it required?
- A receptacle with internal shutters that prevent insertion of foreign objects, required in all new residential construction (Correct answer)
- A receptacle with a lock on the cover
- An outlet that requires a key to operate
- A childproof outlet cover plate
Correct answer: A receptacle with internal shutters that prevent insertion of foreign objects, required in all new residential construction
Tamper-resistant receptacles (TR) have spring-loaded shutters that only open when equal pressure is applied to both slots simultaneously (like a plug), preventing children from inserting objects. Required in all 15A and 20A residential outlets.
Question 5: What wire types are approved for residential branch circuit wiring?
- NM cable (Romex) for dry locations and UF cable for underground/wet locations in most residential applications (Correct answer)
- Any type of wire can be used anywhere
- Only metal-clad cable is approved
- Residential wiring has no wire type requirements
Correct answer: NM cable (Romex) for dry locations and UF cable for underground/wet locations in most residential applications
NM (non-metallic sheathed) cable is the most common residential wiring for dry interior locations. UF cable is rated for direct burial. MC (metal-clad) cable is required in some jurisdictions and commercial applications.
Question 6: What should an inspector verify about bathroom exhaust ventilation?
- That a mechanical exhaust fan vented to the exterior is installed in every bathroom, or that an operable window of adequate size is provided (Correct answer)
- Exhaust fans are optional in all bathrooms
- Only bathrooms with showers need ventilation
- Bathroom ventilation is not part of building inspection
Correct answer: That a mechanical exhaust fan vented to the exterior is installed in every bathroom, or that an operable window of adequate size is provided
Building codes require bathrooms to have either a mechanical exhaust fan ducted to the exterior or an operable window with minimum size. The fan must exhaust outdoors, not into an attic or crawl space.
CBI Electrical Systems Inspection 2
What is proper grounding and why is it essential in electrical systems?