The power of Rising voltage is doubled in electric terrain, and electric terrain gives a 1.5x boost to electric type moves. Do these boosts stack to make it a 3x move or is the electric terrain boost ignored?
No, Rising Voltage only gets the 2x boost from its description to become 140 and not the additional boost from Electric Terrain. If course, this only applies if you are affected by Electric Terrain as well.
Also, I tested it On Showdown!