Low-voltage covers all home systems operating below 50 volts: structured data cabling (Cat6A Ethernet to every room), coaxial cable for video, speaker wire for whole-home audio, security system wiring, and home automation control wiring. Pre-wiring during construction costs a fraction of retrofitting after walls close — typically $800–$2,500 for a complete low-voltage rough-in versus $3,000–$8,000+ to run cable through finished walls. RainFire Builders recommends, at minimum: Cat6A to every bedroom, home office, TV location, and network closet; speaker pre-wire in main living areas and primary bedroom; and security sensor wiring at all exterior doors and windows.