Because it carries such low secondary power, low voltage wiring requires only a thin layer of plastic insulation. Low voltage wiring may consist of a single conductor or multiple conductors wrapped in cable. This type of wiring encompasses a variety of uses from connecting simple bells and chimes to wiring sophisticated home theater, telecommunications, and computer networking systems. Typically, low voltage wires extend in size from 14 gauge down to 24 gauge (AWG) and even smaller. The NEC does not permit this type of wiring to run in the same raceways, conduits, or cables as wires carrying normal voltage. In addition, low voltage wires may not occupy any electrical box containing higher voltage wiring, unless the box is properly partitioned. Low voltage wires must generally be separated from higher voltage wiring by 2 inches or more.
Wire Type |
Description |
Gauge |
Typical Usage |
Lamp Cord
Zip Cord |
Two insulated wires that can be pulled or “zipped” apart |
18 |
Lamps, small appliances, cords |
Flat Ribbon Cable |
Several insulated, color coded wires that can be “zipped” apart |
24 |
Computer circuit/ serial bus connections for keyboards, scanners, printers |
Bell Wire |
Single or multi-stranded, insulated, color coded |
18 |
Bells, chimes, thermostats, timers, control circuits |
Video Coaxial cable |
A single insulated wire wrapped by a foil and braided shield |
RG-59
22-Guage
Core |
Television antenna connections, home entertainment |
Quad-shielded cable containing 2 foil shields, 2 braided shields |
RG-6
18-Guage
Core |
Cable, satellite television antenna connections, home entertainment |
D-station Cable |
Cable containing four insulted, color coded wires |
24-28 |
Permanent, indoor, home telephone wiring |
Category 5 Cable |
Cable containing four pairs of insulated, color coded wires |
24 |
Increased circuit capacity for home computer, telecommunications |
Creating Low Voltage Lighting Designs
Installing low-voltage lighting is one of the most popular do-it-yourself projects. Since the systems operate on only 12 volts of power as opposed to the 120 volts of only 12 volts of power as opposed to the 120 volts of standard line voltage, installing a low voltage system is much sager than working on house wiring. Some manufacturers recommend turning on the power to connect the lights, so you can see the results right away. (Always follow the manufacturer’s directions.)
Installation is easier, too. For most systems, plug in a step down transformer to a standard GFCI protected outdoor, and run the wires to the light fixtures. Working with low voltage wiring means there is no need to bury wires in conduit or as deeply as standard wiring. Requirements vary, but most manufacturers call for direct burial of a few inches.
The quick installation also means it is easy to change the system by adding new fixtures or moving fixtures to new locations. That is real plus because landscapes tend to change over time and a low voltage system can change with the environment.