I was involved with the thread that had been thought to have phone disruptions caused by a balast. It had been found that the cable guy had made some wrong connections and the problem was resolved.
However, I have a 1000w digi balast that causes tv interference with the lower and higher channel receptions. It was only when the balast was running but now find the problem lingers even when not.
It's a Lumatek balast and I chose that one because they claimed to have resolved the interference issue but it seems they had not.
I have another 400w balast that does not cause any problem, unknown model, but I need the 1000w for the developement of THCV in the strain I have growing. To produce THCV, a 1000w HID bulb is a minimum requirement. I had hoped that a combination of bulbs that would add up to 1000w or more would work but it doesn't work that way. It's the intensity of the bulb not the total lumens that does the trick.
EDIT: Google "balast interference" and you will come up with alot of info on the subject.