The overhead power line effectively has an air dielectric and therefore {HEAD ~ the speed} of signals on the line is close to that of the speed of {TAIL ~ light} in air, 300 m/uS 
The overhead power line effectively has an air dielectric and therefore { HEAD ~ the speed } of signals on the line is close to that of the speed of { TAIL ~ light } in air , 300 m / uS
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH