Do your LEDs blink if you stop/start a high current appliance (e.g. a vacuum cleaner) on the same circuit?
No. It only reacts when the relays discharge. I have a 48 VDC 5A power supply to run my LED drivers and a 12vdc 3A power supply to run my arduino and cooling fans. I am using a 5v regulator that stepsdown the 12vdc to give power to my relay board. In order for all PWM drivers and fans to work, everything is on a common ground. I think I might have to isolate the relay board with its own 5vdc power supply that doesn't share the same common ground. I don't know if I can do that since my relay board doesn't have the VCC JD-VCC jumper on it.
This is my basic setup. I have added a few thing since this pic.