Theoretically the current runs at 230V, 50 Hz AC but it sometimes drops down to 180V or less. Despite improvements to electrical supply in Yangon over the last few years, power cuts are still quite frequent. In many villages electric power is supplied only during the evening for a few hours. Do not forget to bring your flashlight. Be careful, because slim batteries are not easily available in Myanmar.
The electrical supply network in Burma is not very reliable. There is much overvoltage, especially during the dry season. Thus, if you plan to plug in electrical appliances it is advisable to use a plug with power surge protection.