Are there LED (retrofit) lights that are compatible with a 120V 14W fluorescent ballast? Or does the ballast always have to be removed?
There are multiple types of retrofit kits. Universal they can work with a ballast or be direct wire. Ballast only these lamps usually have a list of ballasts that work with the LED lamps. And direct wire only, these the ballast must be bypassed and the tombstones can not be shunted. So yes there are some LED lamps that can work with some ballasts.