In order to compare the radiation measurements in Power Line Communications (PLC) systems, the detected radiation intensity in the actual measurement distance needs to be converted to that in the normative distance based on the extrapolation factor. This paper derives the extrapolation factor for PLC radiation measurements within the frequency range 150 kHz to 30 MHz by a Hertzian dipole and using MAXWELL’s equations. The theoretical results show that the extrapolation factor from over 3 m to the normative distance 3 m will decrease with increase of frequencies. Moreover, an experimental approach for PLC radiation measurements in the frequency range 150kHz to 30MHz is proposed and performed in the shielded room. The analysis shows that the extrapolation factor derived from the measurements verifies the analytical results.