For electric shock at low voltage, a person would have to cut their hand (or have wet hands) while at the same time providing a good return path to ground. Seems unlikely, but I'm not saying you shouldn't consider it...

The outdoor safety standard I have available for reference is IEC / UL 60950-22, titled "Information Technology
Equipment – Safety – Part 22: Equipment to be Installed

Below is the relevant portion of clause 6.1


6.1 Voltage limits of user-accessible parts in outdoor locations

USER-accessible conductive parts in an OUTDOOR LOCATION shall meet the requirements for an SELV CIRCUIT in 2.2.2 and 2.2.3 of IEC 60950-1, except that the voltage limits shall not exceed:

– 15 V a.c., 21,2 V peak, or 30 V d.c. under normal operating conditions (see 2.2.2),

– 15 V a.c., 21,2 V peak, or 30 V d.c. for longer than 0,2 s under single fault conditions (see 2.2.3). Moreover, the voltage shall not exceed 30 V a.c., 42,4 V peak or 60 V d.c.