An in-depth study of the harmonic orders inherent in a power system network is required before mitigation techniques are adopted. This paper studied the harmonic orders of the 33 kV Abuja Steel Feeder modeled as a harmonic source using measured data. Readings of kW, kVar, kV and Hz were obtained using power quality analyzer (PQube) to identify the trend and the harmonic unbalance on the feeder. Electrical Transient Analyzer Program (ETAP) software package was deployed to perform Discrete Fast Transform (DFT) while the input parameters were the resultant relative amplitudes and phase angles for both the current and voltage source models. The current source model spectrum of the feeder under study revealed that the 11 th and 13 th harmonic orders have the highest percentage of amplitude relative to the fundamental compared to the other harmonics. On the other hand, the voltage source model spectrum showed that the 14 th , 15 th , 16 th , 17 th , 32 nd , 33 rd and 34 th harmonic orders have higher percentage of relative amplitude. However, only the 3 rd and 5 th harmonic orders were found to cause severe harmonic distortion of voltage and current after harmonic analysis and frequency scan were performed on the ETAP platform.