IEC Special Occupancies and Equipment 4 — Questions and Answers
Question 1: A receptacle installed within 6 feet of a hydromassage bathtub must be protected by:
- AFCI protection
- GFCI protection (Correct answer)
- Tamper-resistant covers
- A dedicated circuit only
Correct answer: GFCI protection
NEC 680.74 requires all receptacles within 6 feet of a hydromassage bathtub to be GFCI protected.
Question 2: What is the maximum voltage permitted for underwater pool lighting in a wet-niche fixture?
- 12 volts
- 15 volts
- 30 volts (Correct answer)
- 120 volts
Correct answer: 30 volts
NEC 680.23(A)(4) permits wet-niche luminaires to operate at no more than 150 volts between conductors, but the practical limit for underwater fixtures is 30 volts.
Question 3: In a Class I, Division 2 location, which of the following is NOT required to be explosion-proof?
- Luminaires
- Switches and circuit breakers
- General-purpose motors that won't arc normally (Correct answer)
- Conduit seals
Correct answer: General-purpose motors that won't arc normally
In Division 2 locations, motors that are not normally arcing and are totally enclosed may be used without explosion-proof listing, unlike Division 1.
Question 4: Mobile home parks must provide each lot with at least a minimum electrical service of:
- 30-ampere, 120-volt
- 50-ampere, 120/240-volt (Correct answer)
- 100-ampere, 120/240-volt
- 200-ampere, 120/240-volt
Correct answer: 50-ampere, 120/240-volt
NEC 550.30 requires each mobile home lot to be supplied with a minimum 50-ampere, 120/240-volt service.
Question 5: For a grain storage elevator, the area within 3 feet of any opening in a belt or bucket elevator housing is classified as:
- Unclassified
- Class II, Division 2
- Class II, Division 1 (Correct answer)
- Class III, Division 1
Correct answer: Class II, Division 1
NEC 511.3 Table defines the area within 3 feet of openings in grain elevator housings as Class II, Division 1 due to constant grain dust presence.
Question 6: Which wiring method is specifically prohibited in theaters for use above the stage?
- Metal-clad cable (MC)
- Rigid metal conduit (RMC)
- Type NM cable (Correct answer)
- Intermediate metal conduit (IMC)
Correct answer: Type NM cable
NEC 520.5 prohibits Type NM (nonmetallic-sheathed) cable above stages in theaters due to the fire hazard from scenery and equipment.
Question 7: Shore power receptacles at a marina must be located within how many feet of the boat slip they serve?
- 10 feet
- 20 feet (Correct answer)
- 30 feet
- 50 feet
Correct answer: 20 feet
NEC 553.11 requires shore power receptacles to be located within 20 feet of the bow or stern of the boat slip they serve.
IEC Special Occupancies and Equipment 4
A receptacle installed within 6 feet of a hydromassage bathtub must be protected by: