Then expect an electrician to stick 12V or 24V down it from time to time.
As an electrician I feel personally attacked. Usually we stick 120V down it! No messing about with that extra low voltage rubbish.
I've done an optoisolated digital input into a DAQ before, put a current source to drive the LED that could take up to 340V forwards, and a similar reverse diode. This paid off within a week of putting it to use when it got hooked to a packaged system with multiple pieces of equipment in a pelican case powered via a 240V single phase generator (EU grounded neutral and 240V phase style, not US split phase style) and a ground wire broke, putting 120V with more than a couple mA of current behind it from power supply emi cap leakage on all the 'grounds'. If you can allow for it, expect mains everywhere

But yeah, using an oversized resistor on user accessible terminals is insurance against dumb end users to to a degree.