Narrowband Power Line Communication (NB-PLC) involves transmitting data by overlaying a high frequency low amplitude signal (ranging from 9 kHz to 500 kHz) onto the low-frequency high amplitude signal (50 Hz to 60 Hz) of the power grid. While using the existing power grid for communication is convenient, it was not originally designed for this purpose, leading to challenges such as conducted emissions and infrastructure constraints. To overcome these technical obstacles, power line filters (PLFs) are a viable solution. The results of our research work, focusing on the optimization of PLFs for NB-PLC to ensure their design fits the needed use case while avoiding over-engineering, are presented in this article. Our study concentrates specifically on the filtering of PLC signal and conducted emissions up to 500 kHz. Building upon a PLC PLF extensively discussed in our previous work—which blocks the PLC signal in the CENELEC-A frequency band regardless of its placement within the electrical installation, sometimes leading to over-engineering—this research aims to adapt the filter order and components for a variety of real scenarios in CENELEC-A, FCC, and ARIB frequency bands. By characterizing different filters, our work provides tailored solutions for these scenarios and serves as a framework for future filter designs in PLC applications.