Best answer by cam
Great question and the supported voltage depends on model.
See here for the spec sheet: http://go.nutanix.com/rs/nutanix/images/Nutanix_Spec_Sheet.pdf
If the model lists 100-240v as acceptable then that means that particular block supports 110v. However, if it lists 180-240v then you will need 208v in order for the block to be supported in a fully redundant manner, meaning that a single PS in the block can support all of the components running within it.