What is minimum height a wall junction box must be from ceiling?
I agree with 3phase there is no height limit by the NEC but there may be a limit by the manufacturer on how close it can be as not to start a fire or scorch the sheetrock, a bit more info would be helpful, if it is led or CFL there is probably nothing to worry about, incandescent or halogen can be converted to led but both of those types of lamps put out a lot of heat.