Lighting Guide for Line Voltage Installation and Use

Q: What is line voltage?

A: Line voltage is the electric energy measured in volts that your local power company delivers through power lines directly to your home, lighting all fixtures and electrical appliances. The main difference between low voltage and line voltage is that low voltage is a direct current whereas line voltage is an alternating current. It is essential to have a certified electrician install any line voltage fixtures!

 

Q: How many volts are commonly delivered to American homes; what is standard?

A: 120 volts is the standard line voltage delivered to American homes. It is the voltage that travels from your local utility substation to your home. Nearly all indoor residential light fixtures and most home appliances run on line voltage. A 120 volt light bulb can usually be screwed into an indoor light fixture, operating correctly without complication or adaptation. Since lights and appliances are designed to run on 120 volts, they can simply be plugged into an indoor outlet.

 

Q: Why is low voltage the standard for outdoor use?

A: The reason low voltage lighting is used outdoors is because it’s safer. If the wire for a 120 volt light source were to become exposed, it could be very dangerous. If someone were to come in contact with 120 volts of electricity, there’s a greater risk of a dangerous electric shock. Contact with a lower voltage wire simply reduces the risk of electric shock danger if a person were to come in contact with a wire.

 

Q: How do I know what voltage bulbs or lamps I need to buy?

A: When purchasing a new light fixture you must always match your light bulb (or lamp) to the requirements of the fixture.

 

Q: How do I go about installing an outdoor line voltage lighting system?

A: When installing a line voltage outdoor lighting system you will want to contact your local building codes departments before you start. This is necessary so you know what installation compliance is required, and so you can pass inspection and certification.

 

Q: Where will the outdoor line voltage lighting system be installed?

A: Your electrician will most likely want to install the line voltage wiring system underground. Wiring the system underground is far safer and less prone to accidental damage. Cable runs underground should be protected by PVC conduit, solvent-welding together with straight connectors, to make a continuous run. Cables must be buried 18 inches beneath paths or patios and 30 inches beneath lawns and flowerbeds.

Additional underground considerations: A building permit is required for running line voltage cable outside. Local codes vary considerably, so have your building department approve your plans before you start work. Be clear on what sort of cable and/or conduit is required, how deeply underground it must be buried, and what type of weather-tight connections and fixtures are required. You must also contact other utilities to locate underground cables and pipes before you begin digging.

 

Q: What if we don’t want to bury lines underground; what is an alternative?

A: If in the rare instance that the line voltage wiring system would be installed overhead, a PVC sheathed cable will span between the buildings that is 10 feet or less. Longer spans must be supported by a tensioned support wire and cable buckles. This wire must be grounded to the house’s main grounding point. The span must be at least 12 feet above ground over a path, and 17 feet above ground over a drive or other area with vehicular access.

 

Summary: A building permit is required for running line voltage cable outside. Local codes vary considerably, so have your building department approve your plans before you start work. Be clear on what sort of cable and/or conduit is required, how deeply underground it must be buried, and what type of weather-tight connections and fixtures are required. You must also contact other utilities to locate underground cables and pipes before you begin digging. Hooks & Lattice always recommends hiring a licensed contractor for all installation.