Recessed LED Panels, Troffers, Lay In and Grid Lighting are an easy cost effective way to light a retail, commercial, or industrial space easily and effectively. Generally spacing ranges from 8-12 feet. There are other factors dependent on spacing such as the application and desired light levels. Please be sure to check your local code if this is for new construction. If you are converting from T12 or T8, the switch is almost always a one for one switch. Sometimes it can be less but usually will require a different ceiling configuration, thus requiring rewiring usually outweighing benefits gained from eliminating fixtures.