If you are installing low-voltage landscape lighting, then one of your most important tasks is to create a waterproof electrical junction where the main power supply joins the individual light fixtures. It's not difficult to do, but many homeowners neglect the need to create a moisture-resistant, rugged connection from the outset. This can result in the need to dig-up cables and replace electrical components. Below is how you can easily create a watertight junction that will hold-up against the elements and provide reliable, uninterrupted power to your low-voltage lighting:
What you will need
- Landscape lighting low-voltage supply cable
- Landscape lighting fixture cables
- Twist-on connectors
- Electrical tape
- Wire stripping pliers
- Tube of silicone sealant
- Low-voltage electrical junction box
Step-by-step guide to creating waterproof junctions
1. Keep safety first - While working with low-voltage landscape lighting is generally safe, you can still endanger your life should you make a mistake while working with higher household current. For example, be careful not to accidentally cut into wiring carrying 120-volt alternating current (AC). To be completely safe, never strip wires on low-voltage wiring that is energized and keep all master power supplies disconnected.
2. Verify your transformer can provide adequate power to the fixtures - To create a sound, waterproof electrical junction, you will need to join all ends of the low-voltage wiring, both fixtures and the main power cable from the transformer. However, before doing so, you must verify your transformer is capable of powering all attached fixtures. Calculating this is easy: simply add up all the individual fixture wattage totals and compare it to the transformer's wattage rating.
For example, if you have a 75-watt transformer, and you are joining three 15-watt fixtures, then the total power consumed is 45 watts, which is well below the 75-watt threshold. Exceeding the maximum wattage can cause the transformer to repeatedly blow fuses, trip breakers or even cause an electrical fire, so be sure your transformer can handle the load.
3. Run wiring into the junction box - After you are satisfied in your transformer's capacity to power your lighting, insert each pair of fixture wires into the junction box through the appropriate hole or slot. Next, insert the pair of wires leading from the transformer into the box.
4. Strip insulation from the ends of the wiring - After running the wire ends into the junction box, the next step is to remove the insulation of all wiring to be connected. Using a pair of wire stripping pliers, remove one-inch of insulation from the ends of the main power supply cable and all of the fixtures. Snip off any excess, "stray" wires that may protrude and re-strip any wires that do not have a clean end.
5. Twist all like wire ends together - Once all the wire ends are stripped, identify all of the "hot" wires and all of the neutral wires; to know which is which, your wiring will contain small white lettering on the "hot" wire insulation with the neutral wires left unmarked.
Next, lay all of the ends of the stripped "hot" wires together, and hold them together in the fingertips of one hand. Neatly twist the uninsulated ends together with your other hand until they are thoroughly interwoven; don't twist them too much to avoid breaking individual wire strands. Repeat this same procedure with the neutral wire ends, and you will have two twisted bundles of wiring if done correctly.
6. Fasten the wire ends together - After you have twisted together the "hot" wire and neutral wire ends, obtain two twist-on connectors, sometimes called wire nuts, that are large enough to fit over the twisted bundles. However, be sure the twist-on connectors are not too big; you want the connection to feel snug inside the connector without a lot of excess movement.
After getting the correct connectors, push the twisted ends of the wire into the connectors and begin to tighten the connectors by turning it clockwise. Keep turning until the connectors tighten and can't be easily budged. Next, insert a few drops of silicone sealant into the connectors so the twisted bundles are sealed from moisture intrusion.
Place the two twist-on connectors side-by-side, then wrap high-quality electrical tape around the wire nuts and the first couple of inches of insulated wiring protruding from the connectors. Don't use cheap, low-quality electrical tape, as it will unravel within a short period of time.
7. Seal the junction box - Once the wire ends are firmly joined together, push the connections into the junction box and fasten the lid to seal the inside of the box from moisture. The box can now be safely buried or mounted to a suitable location in the landscape.
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