Some questions for those of you familiar with commercial LV service. Please forgive my ignorance, but my studies of American wiring have been solely on residential 120/240V systems.
I know that 3-phase services are used at 120/208V and 277/480v, and I believe there is also a single-phase 3-wire 240/480V service.
What type of premises usually take each of these types of supplies? Are one or more types only found in certain areas and/or maintained for historical reasons but not installed new any more?
In business premises getting 240/480 or 277/480, how do they obtain 120V for normal office equipment etc.? Is there usually an on-site transformer, or does the utility provide a separate 120/240 or 120/208 supply?
Thanks.
