E2 Plan Review and Inspections 2 — Questions and Answers
Question 1: During a plan review for a commercial building, the inspector notices that the electrical drawings lack a fault current calculation. What should the inspector require before approving the plans?
- Approve the plans and note the deficiency for field inspection
- Require the engineer to provide available fault current calculations and equipment interrupting ratings (Correct answer)
- Accept the plans if the equipment is listed by a nationally recognized testing laboratory
- Request only the load calculations since fault current is determined in the field
Correct answer: Require the engineer to provide available fault current calculations and equipment interrupting ratings
NEC 110.9 and 110.10 require that equipment have adequate interrupting ratings and be protected against fault currents, which must be verified during plan review.
Question 2: A commercial plan set shows a 480V, 3-phase panel with a 400A main breaker but the service conductors are sized for only 350A. What is the correct inspector action?
- Approve the plans since the breaker protects the conductors
- Reject the plans and require conductors sized to at least 400A or a smaller main breaker (Correct answer)
- Allow the installation if conductors are in conduit rated for 90°C
- Require the contractor to provide a written justification for the undersizing
Correct answer: Reject the plans and require conductors sized to at least 400A or a smaller main breaker
NEC 230.90 requires the service overcurrent device to not exceed the ampacity of the service conductors it protects.
Question 3: When reviewing plans for a commercial occupancy, which document is most important for verifying that proposed wiring methods are suitable for the environment?
- The project schedule submitted by the general contractor
- The architectural reflected ceiling plan
- The specification section listing approved wiring methods and environmental conditions (Correct answer)
- The owner's equipment purchase orders
Correct answer: The specification section listing approved wiring methods and environmental conditions
Specification sections detail approved wiring methods, environmental conditions, and material standards that the inspector uses to verify NEC compliance.
Question 4: A plan review reveals that a mechanical room will house a 480V motor control center (MCC). The plans do not show working space clearances. What should the inspector do?
- Approve the plans and verify clearances during the rough-in inspection
- Reject the plans and require dimensioned working space drawings per NEC 110.26 (Correct answer)
- Accept the plans if the MCC is listed equipment
- Allow the installation if the room is at least 10 ft × 10 ft
Correct answer: Reject the plans and require dimensioned working space drawings per NEC 110.26
NEC 110.26 requires specific working space clearances that must be shown on plans so the inspector can verify compliance before construction begins.
Question 5: During an inspection of a commercial building under construction, an inspector finds conduit installed in a concrete slab that is not listed for concrete encasement. What is the correct action?
- Allow the installation if the concrete will protect the conduit from physical damage
- Issue a correction notice and require removal and replacement with listed concrete-encased conduit (Correct answer)
- Approve the work if the contractor provides a written warranty
- Accept the conduit if it meets the same trade size requirements
Correct answer: Issue a correction notice and require removal and replacement with listed concrete-encased conduit
NEC 358.10 and related articles require that wiring methods be listed and suitable for the conditions of use, including concrete encasement.
Question 6: A commercial electrical plan shows twelve 20A, 120V circuits in an office area. The inspector calculates the load exceeds the panel's available capacity. What action should be taken?
- Approve the plans if the circuits will not all be used simultaneously
- Reject the plans and require an amended load calculation and panel schedule showing adequate capacity (Correct answer)
- Allow the installation if a demand factor is applied by the contractor in the field
- Accept the plans and note to verify load during final inspection
Correct answer: Reject the plans and require an amended load calculation and panel schedule showing adequate capacity
NEC 220 requires load calculations to confirm panel capacity before approval; the engineer must revise plans to show compliant capacity.
Question 7: When inspecting a commercial service entrance, the inspector observes that the service conductors pass through a basement ceiling space without conduit protection for approximately 8 feet. Which NEC requirement addresses this?
- NEC 230.50, which requires service entrance conductors to be protected where subject to physical damage (Correct answer)
- NEC 300.11, which requires conduit to be supported at maximum 10-foot intervals
- NEC 230.43, which lists permitted wiring methods for service entrance conductors above ground
- NEC 110.14, which governs conductor terminations at service equipment
Correct answer: NEC 230.50, which requires service entrance conductors to be protected where subject to physical damage
NEC 230.50 requires service entrance conductors to be protected against physical damage, typically requiring conduit in accessible areas such as basement spaces.
E2 Plan Review and Inspections 2
During a plan review for a commercial building, the inspector notices that the electrical drawings lack a fault current calculation.
What should the inspector require before approving the plans?