HI, New to L/V lighting and questioning the viability of this set-up. I am looking to add 2 Woodsman Integrated Single Source LED Downlights secured to trees near the entrance of my long driveway. The problem is that where I would hang the transformer is ~330 feet from the entrance of the driveway. If I used the Clamp-Connect 300 Watt (12v/15v) Multi-Tap Low Voltage Transformer and connected 10/2 gauge wire to the 15v tap, would that sufficiently power the fixtures at the end? Based on voltage drop calculation (Length of Run * Total Wattage) / Cable Constant: the total voltage dropped at 330 feet with with 10/2 gauge wire powering 18 watts (incase an additional fixture is needed) would be 0.5 volts. Multiply that by 2 (due to the fixtures being in the 2nd half of the run), and you get only a 1 volt dropped at the last fixture. I am not sure if this is a correct formula or if there are other variables that need to be considered. Any help or recommendations would be greatly appreciated! Thank you
Doug: you are correct, there is only a 1 volt loss for 3x6 watt fixtures at the end of 330 feet of 10 gauge wire. You could use the 8 gauge wire that Volt sells (cable constant 18960), but the benefit is minimal - a 0.67 volt loss for 330 feet. However, all Volt lights come with 18 gauge lead wires. Thus the 40 feet of 18 gauge wire on the Woodsman lights will add another one third volt loss. Either way, it appears you are well within the operating limits of the transformer and lights when using the 15 volt connector. Thus the question is, as you have already asked, are there other factors that come into play that would prevent you from running 330 feet of main line? Evan should be able to answer that, but voltage loss across 10 gauge wire doesn’t appear to be one of them. Just out of curiosity, how do you plan to dig 110 yards of cable trench? I hope not by hand. Bob
Thank you for the reply Bob. The 40 foot line from the Woodsman is a great point that I will need to consider. Trenching is the next issue that will likely either make or break the worthwhileness of this project. Going to see how many boulders I encounter on the route and what, if anything, can be done about them. At least I can verify that voltage drop is not an issue!
Although we do stress recommendations like "good for uses up to 300ft for 10-gauge", the reality is low-voltage LED can be/is quite flexible. As long as you're using the correct gauge of cable, proper voltage tap based on your calculations (with a voltmeter possibly), and not overloading the particular run with too many fixtures (and the transformer in general of course), you can typically 'bend the guidelines' per se. Which, from what has been described, you shouldn't have any issues with a fixture at that distance. We do have a manual trenching tool: The Spade Stomper It may not be ideal for your project but, worth mentioning!
Thanks Evan and Bob, The local Home Depot has a rental trencher that I was looking at. Thing is huge but looks like it would make easy work out of my run. Also had a question about transformers if either of you could chime in. Looking at either: 1. VOLT® Clamp-Connect 300 Watt (12v/15v) Multi-Tap Low Voltage Transformer or 2. VOLT® 300 Watt (12v-15v) Multi-Tap Low Voltage Transformer With the 12v-15v version, is it expected that there will only be one run? Saying that because I only see one com terminal whereas in #1 there are multiple. Although I like the simplicity of the clamp-connect style, the 12-15v version (#2) may be better suited to handle the varying size runs that I could potentially set up. From the transformer location, I may setup multiple runs from 10 feet up to the 300 foot one we discussed. Seems like have the flexibility to fool around with 12 to 15 volts would be better than being locked into either 12 or 15v. However, if it is expected that the 12-15v only would be used for one run, then I would prefer #1. That being said, by using 15 volts in a situation where 12 volts is just barely not enough going to greatly reduce the life of the lamps? Thanks for any help you guys can provide!
Doug: My preference would be to opt on the side of future expansion capabilities. The clamp-connect transformer will give you that as it can handle up to 5 main lines. The 300W Slim Line would be another option for you as it can also take up to 5 main lines. That said, I installed a 100W Slim Line which only has four 15V connections. I thought that would be sufficient and it was, barely. Installing lights became an addiction. By the time I finished I maxed out my transformer, using all 4 connections, each running to a ProJunction hub, feeding a total of 29 lights. A 300W, 5 connection transformer is going to give you a whole bunch of future high wattage bulb capability. Most of the bulbs sold by Volt have an operating range of 6-18 volts, with noticeable loss of luminosity below 10-11 volts (specifications section in the bulb description). If you search the forum for the word “voltmeter” you will find several threads by Evan talking about using a voltmeter to check fixture voltages. Thus, when a fixture at the tail end of a 12 volt mainline drops to 10-11 volts, give or take, you up the connection to 15 volts (If you don’t own a multimeter, Volt sells one in the tool section). The discussions on the internet of burning out 12 volt LED bulbs at elevated voltages are usually related to idiots trying to use 12 volt LED strip lights in a 24 volt system. There shouldn’t be any appreciable loss of lifespan when using Volt bulbs and integrated lamps at 15 volts. Go with option 1. Bob
