The electrical power supplied to the countries of the world is typically 50Hz or 60Hz. The electric power frequency is shown in the number of hertz (cycles per second). This means that the flow of the electrons switch or reverse polarity 50 or 60 times per second. The United States for example is 60Hz. Other parts of the world are 50Hz. This is to say that when we sell a lamp for the US market, we assume that the power supply that drives this lamp will be 60Hz. By the same token, when we sell a lamp to a country with 50Hz power, we assume that it will be operated on a 50Hz source. Here is a great website that you can refer to on this subject. http://www.kropla.com/electric2.htm
Medium pressure mercury vapor and metal halide lamps have a few quirks and one of
them is that they can be, depending on the arc length, frequency sensitive.
The condition with the plasma arc wiggling or snaking is commonly referred to as acoustic arc resonance.
Read more on “Acoustic Arc Resonance”