TL;DR
Study the assessment and management of eye, ear, nose, throat, and facial emergencies. These specialized assessments require specific knowledge tested on the Master Electrician License Exam.
Free Service Entrance Sizing Practice Questions
Master Electrician License Exam · Services & Feeders
This module covers Service Entrance Sizing as part of the Services & Feeders section, testing your understanding of core concepts and their practical application.
| Exam | Master Electrician License Exam |
| Pass Rate | 45% |
| Duration | 300 minutes |
| Module | Service Entrance Sizing |
Why Service Entrance Sizing matters
Service Entrance Sizing is heavily tested because undersized conductors and services cause overheating, fires, and equipment failure.
Sample Practice Questions (5)
1. A commercial building has a calculated demand load of 800 amperes at 480Y/277V, 3-phase. The service entrance conductors must be sized per NEC 230.42. If using parallel sets of conductors, what is the minimum number of 500 kcmil THWN-2 copper conductors per phase required? (500 kcmil THWN-2 Cu = 380A at 75°C)
- 3 conductors per phase (3 × 380 = 1,140A capacity)
- 2 conductors per phase (2 × 380 = 760A capacity)
- 4 conductors per phase
- 1 conductor per phase
2. A large industrial facility requires two services per NEC 230.2(A) due to capacity requirements exceeding 2,000 amperes at 480V. Per 230.2(D), what additional requirement applies?
- A permanent plaque or directory shall be installed at each service disconnect location denoting all other services supplying the building and the area served by each
- Each service must have its own utility meter only
- The services must be on opposite sides of the building
- A transfer switch must be installed between the two services
3. NEC 230.44 requires that when service entrance conductors are run in parallel, each set must have which characteristic?
- Each parallel conductor set must be the same length, same material, same circular mil area, same insulation type, and terminated in the same manner
- Parallel conductors may be different sizes if the total ampacity meets the load
- Each set must be in the same raceway
- Parallel conductors are only permitted for feeders, not service entrance conductors
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Start practicing free →4. Service entrance conductors supplying a 200-ampere, 120/240V, single-phase dwelling must be sized to carry at least what amperage?
- 200 amperes — service entrance conductors must have an ampacity not less than the rating of the service disconnect
- 250 amperes (125% of 200A)
- 175 amperes (allowing for diversity)
- 150 amperes (with demand factor applied)
5. Under which NEC exception is a second service permitted for a single building?
- When the building has a fire pump requiring a separate service per 230.2(A)(1)
- When the building exceeds 5,000 square feet
- When the building is three or more stories tall
- When requested by the building owner for convenience
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