One time I did a test setup with the antenna and preamp connected to a 4-way splitter and then to two converter boxes, two 8-inch monitors, a Sony 22-inch LCD TV, and signal level meter. This was a temporary setup to compare the sensitivity of the tuners using a step attenuator to bring the signals to the digital cliff. The antenna coax was not grounded.
When I touched the coax and the metal strip on the edge of the counter I felt a mild shock. I investigated further and found that what I felt was the sum of the leakage currents from all of those AC operated devices. The leakage current measured about 200 uA; not a dangerous amount but enough to be felt.
I connected a wire only to the grounding pin of a 3-wire plug (no connection to the other pins), connected the other end of the wire to the splitter case, and inserted the plug into a properly wired 3-wire outlet. This connected the coax shield to the house electrical system ground. The leakage current then measured zero.
So, I'm very particular about grounding the coax shield to the house electrical system ground with a grounding block for personal electrical safety AND to reject interference.
Case history:
http://www.digitalhome.ca/forum/81-o...ml#post1457594
http://www.digitalhome.ca/forum/81-o...ml#post1457668