I would like to control a bank of six relays with my Arduino Uno. The relays are less than 5 meters from the microcontroller, so I'm hoping I can connect things with some medium length (less than 5 meters) wires. In order to preserve output pins on the Arduino and (slightly) reduce the number of longish wires, I'm considering locating a shift register next to the relays and driving the shift register from moderately far away.
Thank you, everyone, for the helpful answers.LarryD: I'm using the relays to switch 24 volts AC (thermostat inputs to a radiant floor heat valve controller). I assumed that for AC I needed to use mechanical relays rather than some sort of solid state alternative, but if I'm wrong about that please let me know -- I'll be pleasantly surprised. I'm relatively new to this stuff.
What I don't know is what effect (if any) the the distributed inductance/capacitance of the wires will have.