Third-order harmonics—commonly referred to as triplen harmonics—are harmonic frequencies that are odd integer multiples of three times the fundamental frequency, such as the 3rd, 9th, 15th, and 21st harmonics. In three-phase electrical power distribution systems, these specific harmonic orders possess unique characteristics because their phase angles coincide, causing their currents to accumulate directly in the neutral wire rather than canceling out. This phenomenon requires facility managers and electrical engineers to install specialized harmonic filters, phase-shifting transformers, or heavily rated neutral conductors to prevent overheating, equipment degradation, and unexpected circuit breaker trips caused by high neutral current accumulations.