A year and a half ago I installed a 150W Slimline transformer and a total of 52W of lights, to the front of my house. I bought the 150W transformer hoping to have enough power for the rear yard as well. I am now looking to add path lights down to our boat dock. The path is very long, 355ft from the transformer to the dock. Obviously this is over the 300ft distance I see quoted by most sources for low voltage runs. Would this work if I used 10G or even 8G wire? Additionally, I am thinking this will require around 20 fixtures at 2W or 3W apiece (60W total). I would also like to add a spot light for up lighting on a cluster of trees which are just off the path beyond our pool area, which would be aroun 18W more. Thoughts on these totals with the 150W transformer? As far as the path lighting, I am going for a subdued look. At the mid point between lights I want the path dimly lit, I don't need to be able to see a needle on the ground. So, I may be able to do it with less total fixtures, but looking for advice. Thanks
Jim30 From my admittedly limited knowledge I'd say you're up against both the overall length and the total required wattage. If you Google "low voltage lighting calculator" and choose some of those top sites you can get a rough idea of voltage drop and recommended wire gauge. Putting your numbers in a couple of calculators did not look promising, you would be over the recommended 80% transformer utilization as well as down in the 6 gauge size which isn't support (IIRC) by Volt transformers. I contacted Volt support about my ~350ft run of 4W fixtures and they indicated it would not work and, as you mentioned, was not a supported distance. I ended up moving my overkill 600W transformer to around a 260ft total length with 10 gauge wire and saw negligible voltage drop at the end of the run (using the 15V connections). My total load, overall cable length, and total supported wattage are obviously different but I'd say you would see noticable dimming at the end of the run with 10 gauge or maybe even 8 gauge. Given the cost of 10/2, and especially 8/2, wire and connectors would you consider adding a transformer somewhere closer to the pool or dock? That would shorten the total distance and give you some flexibility with adding additional fixtures. No idea if it's feasible, just looking for options. I'm not an electrical engineer or electrician, just a homeowner who knows the DIY struggles and is trying to give back a little to the community so take my advice with a large dose of salt. Best Joe
Further to Joe’s great comment, if you look at the descriptions for each transformer, you’ll notice that the transformers at the higher end of the spectrum are the ones most suitable for longer distance home runs. You don’t want to exceed 80% (120W in this case) of your transformer’s capacity and with those 3W lamps added to your total alone, you’d exceed that. Because the 900W and 1200W transformers have 22V taps, they would likely compensate for the voltage drop you’ll likely encounter with a wire run at that distance. But given that your total wattage load would be less than 150w, those higher capacity transformers would probably be way too powerful for your overall needs. I might be wrong but the only way I could see the 150w transformer working would be if you could site the transformer halfway between your house and the end of the path. My advice is to contact customer support for recommendations on the appropriate transformer size, lamp brightness, and cable gauge for your project. They will be able to tell you both what’s most practical and what’s practicable.
Ok, thanks for your thorough evaluation. I knew the distance was going to be an issue and was hoping a larger gauge wire would help out, oh well. I think the best option I have now is to split the run and place a new transformer at the dock. Considering the cost of larger gauge wire for a single run, two runs and a new transformer won't really be much more expensive. The only hassle is wiring an additional circuit at the dock for the new transformer.
