5V 8 relay module

hello!

i am trying to connnect 16 buttons to two 5v 8 relay modules on an 5V 6A power supply.
i have connected +5 to vcc in far left pin/ ground to GND far right pin and use GND to send singal.
the problem i have is that i can have active only 3 replys, if i try to close more than 3 relays nothing happens.

i have a wire running prox 20 metres but 5v do get at the end of the line.

  • if that can help i have an other 5v power supply close to the relays used to power 10 arduino nano.

What is the size of the 20M of wire?

i am trying to connnect 16 buttons to two 5v 8 relay modules on an 5V 6A power supply.

Where is the Arduino in all this?

wiring is UTP i sent 1 pair + and 1 pair -
the arduino is just to explain what the second power supply powers in case that it can be used also for the relays