At this time during this election season I wish to take definite stands on certain transmitter issues.
The FM Rule 15.239 is nonsense. It is nonsense for two reasons. Nonsense Reason No. 1 is that anyone goofy enough to attempt doing something with so weak a transmitter is obviously not able to verify that the field strength meets 15.239. Nonsense Reason # 2 is that the only way to get a solid, multipath free signal using a 15.239 transmitter is to locate it one-foot from the FM radio. The sillyness of 15.239 falls on the FCC.
Carrier Current is dangerous. Radio hobbyists should avoid experimenting with AC powerlines in hope of reaching several extra feet with an AM radio signal. If a member of your family insists on dabbling in carrier current get a big fat life insurance policy on them and there's a good chance you will come into some money.
Only three Part 15 categories deserve full attention:
15.219 AM band broadcasting, 15.217 Long Wave broadcast, and 15.225 Short Wave Radio.
Those three Part 15 categories are worth pursuing for the increased range they provide and being alive for the experience.
In closing may I say the FCC is not your friend. They have jobs, they don't want you causing work.