CEA NEC Wiring and Protection 4 — Questions and Answers
Question 1: Under NEC 225.30, how many sets of service-entrance conductors are generally allowed to supply a building from outside wiring?
- Only one, with limited exceptions (Correct answer)
- Up to three
- As many as needed
- Two per panel
Correct answer: Only one, with limited exceptions
NEC 225.30 generally limits a building to one set of feeder or branch-circuit conductors from outside unless specific exceptions apply.
Question 2: According to NEC 210.19(A), branch-circuit conductors must have an ampacity not less than what percentage of the continuous load plus the non-continuous load?
- 100% of both
- 125% of continuous + 100% of non-continuous (Correct answer)
- 100% continuous + 125% non-continuous
- 125% of total combined load
Correct answer: 125% of continuous + 100% of non-continuous
NEC 210.19(A) requires conductors to be sized at 125% of the continuous load plus 100% of the non-continuous load.
Question 3: Which wiring method is permitted in a Class I, Division 1 hazardous location per NEC Article 501?
- NM cable (Romex)
- Type MC cable without gas/vapor-tight jacket
- Rigid metal conduit (RMC) with explosionproof fittings (Correct answer)
- EMT with standard compression fittings
Correct answer: Rigid metal conduit (RMC) with explosionproof fittings
In Class I, Division 1 locations, NEC 501.10(A) requires threaded rigid metal conduit or steel IMC with explosionproof fittings.
Question 4: Per NEC 334.15, where NM cable is run exposed on the surface of finished walls in a dwelling, it must follow the surface and be protected from:
- UV light only
- Physical damage in exposed or accessible locations (Correct answer)
- Moisture with waterproof tape
- Ambient temperatures above 90°F
Correct answer: Physical damage in exposed or accessible locations
NEC 334.15 requires NM cable run exposed on building surfaces to be protected from physical damage and to closely follow the surface.
Question 5: What is the maximum overcurrent protection permitted for a 12 AWG copper conductor on a general-purpose branch circuit per NEC 240.4(D)?
- 15 amperes
- 20 amperes (Correct answer)
- 25 amperes
- 30 amperes
Correct answer: 20 amperes
NEC 240.4(D)(5) limits 12 AWG copper conductors to a maximum 20-ampere overcurrent device on general-purpose branch circuits.
Question 6: Under NEC 314.16, the volume of a box must be calculated to ensure adequate space for all conductors and devices. What determines the volume allowance for a device such as a switch or receptacle?
- Zero — devices don't count toward box fill
- Twice the volume of the largest conductor connected to it (Correct answer)
- One conductor volume based on the largest conductor connected to it
- A fixed 2 cubic inches regardless of conductor size
Correct answer: Twice the volume of the largest conductor connected to it
NEC 314.16(B)(4) requires each yoke or strap containing a device to be counted as two conductor volumes of the largest wire connected to that device.
Question 7: Per NEC 410.116, a recessed luminaire installed in a thermally insulated ceiling must be listed and labeled as:
- Type IC rated (Correct answer)
- Type NI rated
- Wet-location rated
- Explosion-proof
Correct answer: Type IC rated
NEC 410.116(B) requires recessed luminaires installed with thermal insulation in contact to be listed and marked as Type IC (insulation contact) rated.
CEA NEC Wiring and Protection 4
Under NEC 225.30, how many sets of service-entrance conductors are generally allowed to supply a building from outside wiring?