(a) If measurements are required, they shall be conducted in accordance with the procedures set forth and with instruments conforming to and calibrated in accordance with the IEEE Standard No. 644, Standard Procedures for Measurement of Power Frequency Electric and Magnetic Fields from AC Power Lines, latest revision. Measurements shall be conducted on a fully excited line and recorded continuously over a period of at least 14 days with a sampling rate equal to or greater than one sample per 15 minutes.
(b) Instruments shall have been calibrated within the past 180 days prior to use.