Practice question

What advanced NEC application is important for sizing the neutral conductor in a three-phase roadway lighting system with LED drivers?

  1. The neutral can always be smaller than the phase conductors
  2. The neutral may need to be oversized (up to 200% of phase conductor size) due to triplen harmonic currents from nonlinear LED loads
  3. The neutral conductor is never required
  4. The neutral must always be exactly the same size as phase conductors

Answer: B — The neutral may need to be oversized (up to 200% of phase conductor size) due to triplen harmonic currents from nonlinear LED loads

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