A 3-phase, 4-wire, 120/208-volt system is used in a high-rise apartment building. What is the maximum allowable conductor fill percentage, according to 2026 NFPA 70 NEC?

Texas Master exam practice question · Branch Circuit Conductors

A 3-phase, 4-wire, 120/208-volt system is used in a high-rise apartment building. What is the maximum allowable conductor fill percentage, according to 2026 NFPA 70 NEC?

A40%
50%
C60%
D70%

Exam tip

Be aware of the specific fill requirements for different types of systems to ensure compliance.

Why B is correct

According to 2026 NFPA 70 NEC Article 336.2(A), the maximum allowable conductor fill percentage for 3-phase, 4-wire systems is 50%. The other options exceed the code requirements.

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A 3-phase, 4-wire, 120/208-volt system is used in a high-rise apartment building. What is the maximum allowable conductor fill percentage, according to 2026 NFPA 70 NEC?

A 3-phase, 4-wire, 120/208-volt system is used in a high-rise apartment building. What is the maximum allowable conductor fill percentage, according to 2026 NFPA 70 NEC?

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