EPD UL 891 DFS LV Switchboards can operate safely up to 600Vac.  The complete range is from 120 to 600Vac.  See the complete specifications on our products page. In the US, residential and commercial systems are typically 120/240VAC single phase.  Larger commercial and industrial sites will commonly have 480VAC 3 phase coming into the building and will use this voltage level directly for larger loads.  Where office buildings and smaller loads are present, transformers are used to step down the 480VAC to 120-240VAC.  Usually there would either be a single phase 480:120/240VAC transformer or a three phase 208/120VAC secondary voltage. In the US, the more common low voltages used are multiples of 120VAC.  These include 120, 240, 480, and 600VAC.  The exception is 208VAC and this is used because it takes advantage of a Wye secondary three phase transformer where L-L (line to line) voltage is 208VAC and L-N (line to neutral) voltage is 120VAC.  Since the 120VAC level is required for most small loads and 208VAC is close to 240VAC this type of transformer is commonly used.  Occasionally large buildings may use the L-N of the incoming 480VAC system which is 277VAC single phase.  Since 277VAC is close to 240VAC, many 240VAC nominal loads will be able to run on 277VAC.  Most lighting ballasts can run from 120 to 277VAC.  Many single phase 240VAC nominal motors run from 208 to 277VAC.