I want to place lights in two separate areas in opposite directions from one another. The ideal way to do this would to be run a "main" wire out from the house 60' and then splice in two separate runs of wire so that it runs 60 feet one direction and 90 feet in the opposite direction. Will that work, or will it violate some principle of an electronic circuit? I'll be using 10-2 wire and hoped to avoid running a double run for that first 60 feet. Thanks!
What you propose will work fine, with a caveat. On page 9 of the downloadable installation guide for the 300W multi-tap low voltage transformer you will find a formula for calculating line voltage drop. Your choice of 10-2 wire is a good one as it will minimize the effect of such long runs. The caveat is how many lights will be at the end of each separate branch and what is the total wattage you plan to install. A rule of thumb is no more than 10 lights for a single mainline (although I have 11 on the mainline to my backyard, all 2W and 3W bulbs). Use the formula to estimate the voltage drop for your installation. If it gets close to 2-2.5V, use the 15V tap on your transformer for your mainline connection. Low voltage LEDs don't work well when the voltage at the very end of the longest run drops to somewhere in the 9.5 to 10 range. Have fun. Bob
Bob, much appreciated. I can move forward with your advice by just upsizing my transformer, but figured I'd throw this out there to see if you'd be so kind as to answer a follow up. Please see the drawing attached. For the purpose of calculating my voltage drop, would this be considered a 120' run and a 150' run if that first 60' from the transformer to the split of the 'Y' is shared 10-2, or should I think of this as a 210' run? Thanks!
Another rule of thumb is that the sum total of the wattages of all of your lights should not exceed 80% of the transformer wattage. So long as you are installing low wattage LED lights, and not high wattage halogens, you should be fine, especially since you are using 10-2 wire. Treat the install as a 150 foot run for voltage drop estimation purposes. To be sure, set everything up and measure the final voltage at the most distant light. Any inexpensive volt-ohm meter will do for that purpose, available from Volt or any big box hardware store. Enjoy. Bob
