The risk of damage comes from ESD (static discharge) and EMF (inductive coupling from nearby circuits).
You can guard in two ways:
- shielded cables, with appropriately grounded connectors
- surge suppression diodes
You will still experience data loss during ESD/EMF events, but will be able to avoid catastrophic damage. Another source of data errors will be the difference in ground potential between the two devices. This difference is dynamic, ie, it changes as the load at the two endpoints changes; suppose you turn on a vacuum cleaner or microwave plugged into the same or nearby outlet as one of the two devices. The local ground level will move up by some non-negligible amount.
To minimize data loss, you have two possibilities:
- transceivers which typically incorporate protection, as well as transmit the signal over a differential connection to eliminate common-mode transients.
- lower data rates in the 100Kbps range or less
Update to caution about "long range drivers": Other answers suggest use of buffers or drivers meant for "long range", but you should mind whether the two sides of the bus have a common ground or not. Such buffers are suitable in applications where both ends of the bus reference the same ground, like automotive or instrumentation, but not in residential or commercial applications where each end uses a separate power supply, and thus a different ground reference.