Arduino IO long distance travel
Yes, losses in wires are proportional to the length, so an excessively long wire may not be able to deliver enough power. Many factors come into play here:


higher current consumed by the relay increases the losses
smaller wire diameter increses the losses
the voltage required by your relay defines how much you can afford to lose


For example, a pair of AWG23 wires 30m long will have a total resistance of 4 Ohm. If your relay consumes 100 mA, you will lose 0.4V in the wires. If Arduino delivers 5V, and the relay requires a mininum of 4.5V to work, you're just good enough: you're delivering 4.6V to the relay after the losses.