What maximum length of wire can I use to connect a push button to an Arduino?
Majenko's answer is probably the safest option. There is, however,
something simpler that you can try:


Use a strong pull-up (or pull-down). Something around 1&nbsp;kΩ will
make it quite difficult for the noise to pull your signal low, at the
cost of increased current consumption.
Connect each push button to the Arduino using a twisted pair of copper
wires. This will minimize the inductive pickup effect.