Landscape lighting fixtures and lamps must provide low-voltage power to work properly. Low-voltage cables carry this power from the transformer to the light source.

Low-voltage cables for landscape lighting are generally 2-core cables.

This kind of cable is suitable for direct buried installation and has a variety of specifications to choose from. The smaller the number on the cable specification, the thicker the cable. Thicker cables can transmit power farther than other cables. They also have a higher ampere rated capacity.

Each cable size also has its own cable constant number. This number will be used when the contractor performs voltage drop calculations.

Use cables that comply with industry standards, such as UL 1493: Underground Low Energy Circuit Cables and CSA Standard C22.2.

Stripping. You should have a pair of good quality cable strippers. Make sure not to use them to cut any other types of cables except copper wires. Cutting other types of cables, such as suspension wires, can dull the blade. When stripping the insulation of the cable, make sure not to cut any strands. If it wears out, the 12/2 cable may become 16/2 at the junction. This may cause the joints to heat up and potentially fire.

Connect the cable to the transformer. It is very important to check the manufacturer's specifications on the size of the transformer junction box. Generally, the terminal size can accept multiple cables. When inserting the cable into the terminal, make sure that the strands of the cable are twisted and not frayed. If frayed wires touch from one block to another, it may cause a fire. Tighten the terminal screws until they fit snugly. Grasp the cable and pull down and rotate it clockwise. Tighten the terminal screws to ensure that the cable does not slip out. This approach will provide a strong mechanical connection.

Embedding. The National Electrical Code requires landscape lighting cables to be buried 6 inches below the ground. It is recommended to install the cable in a lawn area 8 to 12 inches deep. Keep all cables away from any lawn edge or flower pot edge, because it can be easily cut by the trimmer. The cable installation in the garden or planting bed should be in a PVC conduit 8 inches to 12 inches underground. This provides additional protection for any ongoing excavations.

Install on the tree. Proper hardware should be used to lay cables in the tree. Always use stainless steel fasteners on the tree. Do not use copper or brass screws as they are toxic to the tree. Never use staples or any mounting hardware that may block the tree to connect the cable to the tree. Install the cable to the tree at least 3/4 inch from the trunk or branch to create a gap. The cables should be strong, but have enough slack to be moved during the lighting maintenance service.

Cable connection. We all have our favorite cable connections. Any connection directly buried in the ground should be used for landscape lights and protected with an approved waterproof material. Choose a connection and follow the cable combination specifications of all manufacturers.

Round SO cable connection. Underwater lights and many brands of low-voltage tavern light strings require special attention when connecting to standard landscape lighting cables. SO cable is a round 2 or 3 conductor cable used in most underwater lights and low-voltage tavern strings.

SO cables usually contain paper or nylon conductor partitions inside. This can act as a wick and draw moisture into the main jacket. When connecting SO cables to landscape lighting cables, it is important to seal the round ends of the cables to prevent any water wicking. This can be done with a piece of resin-filled heat shrink tubing. Some manufacturers provide waterproof junction boxes or IP68 compression connections to create this special connector.

Adjusting the cable size and installing it correctly will allow you to design a real lighting system and provide a trouble-free environment for years to come. Do it right, and recommendations will follow.

Kevin Smith is a national technical support and trainer for Brilliance LED LLC in Carefree, Arizona. You can contact him at kevin.smith@brillianceled.com.