The lights flash when the heater tape is cold and the unit is turned on for the first time. The heat tape draws higher initial or inrush current when it is cold and this sags the internal processors power supply causing it to reset.

You can reduce this problem by running larger supply wire from the breaker box to the SST-2. We provide #10 awg stranded wire to connect to from the controller so it is recommended that you use #10 awg wire to supply the system with even if you are powering it with 120 VAC.