Does 14 CFR 25.1310 apply to hydraulic systems?
Usually this link below can be very helpful in finding guidance for a particular regulation (e.g. 25.1310). In this case there isn't any guidance for 25.1310.

https://www.faa.gov/aircraft/air_cert/design_approvals/transport/rules_acs_policy/

Next try the preamble for when this regulation was passed or introduced and see if the FAA provided any guidance on their intent for the regulation. The FAA discussed an EWIS (Electrical Wiring Interconnect System) accident which only confuses the intent. However I briefly perused the preamble.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/81B77634BED9EAA78625738E007123B3?OpenDocument&amp;Highlight=amdt.%2025-123

25.1310 is in Part 25 Subpart F and most of these regulations (e.g. 25.1309) apply to all systems (e.g. hydraulic, electrical, pneumatic, etc.). Best of luck I hope this helps.