CBD CBD Lighting Design & Electrical Planning 2 — Questions and Answers
Question 1: Under the NEC, which bathroom circuit requirement applies to the general-purpose receptacle outlets?
- They may share a circuit with lighting
- They must be on a dedicated 20-amp GFCI circuit (Correct answer)
- They require a 30-amp circuit
- No special circuit is required
Correct answer: They must be on a dedicated 20-amp GFCI circuit
The NEC mandates at least one dedicated 20-amp circuit for bathroom receptacle outlets to ensure safe, adequate power.
Question 2: What is the recommended lumen output range for general ambient lighting in an average-sized residential bathroom (approximately 50 sq ft)?
- 500–700 lumens
- 750–1,000 lumens (Correct answer)
- 4,000–5,000 lumens
- 2,000–2,500 lumens
Correct answer: 750–1,000 lumens
A 50-square-foot bathroom typically requires 750–1,000 lumens for adequate ambient illumination based on standard lighting calculations.
Question 3: Which bathroom zone classification (per IEC standards commonly referenced in design) designates the interior of the shower or tub enclosure?
- Zone 0 (Correct answer)
- Zone 1
- Zone 2
- Zone 3
Correct answer: Zone 0
Zone 0 is defined as the interior of the bathtub or shower tray, requiring fixtures rated at minimum IPX7.
Question 4: What type of dimmer switch is required when installing dimmable LED fixtures in a bathroom?
- Standard incandescent-compatible trailing-edge dimmer
- A dimmer rated and compatible with the specific LED driver technology (Correct answer)
- Any 0–10V commercial dimmer
- A simple rheostat dimmer
Correct answer: A dimmer rated and compatible with the specific LED driver technology
LEDs require dimmers specifically rated for their driver technology to prevent flickering, buzzing, or reduced lamp life.
Question 5: In a bathroom remodel, why is it important to verify the existing electrical panel capacity before adding new circuits?
- To comply with aesthetic design standards
- To ensure the panel can handle increased amperage load without tripping or hazards (Correct answer)
- To satisfy manufacturer warranty requirements only
- Panel capacity is irrelevant for bathroom additions
Correct answer: To ensure the panel can handle increased amperage load without tripping or hazards
Adding circuits without verifying panel capacity can overload the system, creating fire hazards and code violations.
Question 6: Which wire gauge is required for a 20-amp bathroom circuit per NEC standards?
- 16 AWG
- 14 AWG
- 12 AWG (Correct answer)
- 10 AWG
Correct answer: 12 AWG
A 20-amp circuit requires 12 AWG copper wiring to safely carry the current without overheating.
CBD CBD Lighting Design & Electrical Planning 2
Under the NEC, which bathroom circuit requirement applies to the general-purpose receptacle outlets?