If You want the dimming T5 lamps You needs special dimmable electronic ballasts (for example OSRAM QTi 2X28/54 DIM). This ballast using signal 1-10V for dimming. Use converter from the Arduino PWM signal to 1-10V signal.
Since the electronic ballast does not fully turn off the T5 lamp, it is necessary to put an additional relay to on/off electronic ballasts (if 0 on Arduino PWM output).
