If you have 50 feet of wire going to a sensor, that wire is also an antenna. If you have a thunderstorm, a lightning strike somewhere in your neighborhood can cause damaging voltage levels on the Moteino (and sensor). Also, any local radio transmitters can cause interference any time. You can fix a lot of this* easily with a simple series resistor, parallel capacitor and zener diode or other surge supressor, but only if you design those things in.
*Not counting a direct lightning hit, of course! Direct hits may be rare but you can get "lucky". As a kid my crystal radio had about 50' worth of wire antenna running from my bedroom window to a tree in the yard. We lived on a ridge top. Either the tree, or my wire did take a direct hit one night, and the house caught fire. Fortunately I was not in my room, and we quickly got the fire out although many electrical items in the house were literally toast: light fixtures, telephone, radio, etc.