Hello! New to the forum but total newb regarding landscape lighting. I haven't seen any threads directly discussing specifics regarding choosing the appropriate direct burial low voltage transformers so I thought I'd start one. I'm.working on designing the lighting for my house and yard. My yard has a lamp post near the bottom of the driveway. My intent is to remove the lamp post and to splice the existing wiring (120AC;15A) that is already pre-buried in my yard into a direct burial low voltage transformer which I will use to power landscape lighting in my front yard which is about 100' from my house. I just got my driveway redone and before the new asphalt was poured I had the contractor bury 12 gauge wiring underneath the driveway within a 1/2" PVC pipe that spans the width of my driveway (20'). This will allow me to pull the landscape wiring to what ever length I need and will allow me to install lights on both sides of my driveway. For lights that will accent my house, I'll install a 2nd transformer. With that all said, here are some questions I have in regards to choosing the correct direct burial low voltage transformer: 1. How does one maintain waterproofing for the direct burial boxes that the transformer sits in? Is there a waterproof rating for these like you see for cell phones? 2. Unlike traditional transformers that are readily accessible with a door, how often should one access a direct burial transformer? 3. Should I think about it being BT/WiFi accessible so I don't need to open the waterproof box to adjust settings? 4. Are there any electrical codes I need to worry about that aren't present with traditional low voltage transformers? 5. What are some mistakes that people make that install direct burial transformers? Thanks!
Unsure if my experiences will be helpful but I just went through a similar installation (new driveway, repurposed lamp post circuit, multiple transformers). I researched direct-burial transformers but for my needs there were no upsides over mounting a standard above-ground transformer. My lamp post circuit was accessible from inside the garage and I had plenty of space to mount a transformer and run lines from there. After researching direct burial transformers, I took a step back and reconsidered my layout (maybe ten times). I realized I could put the transformer at the start of the run instead of direct buried in the middle. Obviously this would not be optimal for your needs but something to think about. Placing any transformer at the start of the run (your house) would necessitate the need to run 100' of cable to get to your front yard and then voltage drop could become a concern. Some of the direct-burials I looked at were completely sealed and potted and all connections were made outside the unit. Others provided internal access, and were listed as IP67 rated, but offered no real advantage over above ground for my needs. In the end, I chose to use a gasket sealed above ground unit although I couldn't find an IP rating on them. During my initial setup I accessed the box several times to test connections (12v vs 15v) since I had concerns around voltage drop. If you plan to add additional lights in the future then access would be needed obviously. Since I finished my initial install I haven't opened the transformers at all. IMO absolutely, but that depends on your requirements. There aren't many things to adjust inside the transformer outside of photocell or timer (I am just shy of a noob myself, so I could be missing something). Having wireless access would provide some level of future-proofing if you want to test IoT or "smarthome" features. I added remote access to mine through wifi outlets and Shelly relay switches. Can't comment on questions 4 or 5 since I'm just a DIY'er playing devil's advocate. If you have plantings you can hide a transformer behind then an above-ground in your front yard may prove more flexible in the long-term than direct burial. Just my thoughts, good luck with your project!
Joe - Thanks for all the experience you shared. Unfortunately my lamp post light is on a shared circuit so I don't have the ability to put the transformer in at the beginning of the run. I'm surprised that I can't find more information regarding direct burial transformers. You would think direct burial transformers would be a key element when setting up landscaping lighting on a large property.
