December 9, 2025Dec 9 Hi,I would like to know if I have missed anything, so please let me know what you think about this. The voltage at my home is too high and cannot be lowered; it is around 130/260V and sometimes even higher. I came up with the idea to install an auto-transformer at the entrance of my house to step down the AC voltage by adding two 25-turn, 5.3 mm² (AWG 10) laminated copper windings on both sides of the coil.I tested it with two loads of 1 kW each on both sides of the auto-transformer. It worked well, and after an hour, I did not notice any temperature rise. Below is a schematic of how I plan to install it at the entrance of my house.There are two ways I can connect this auto-transformer: either using the 260V as shown in the image or by connecting it to the 130V line or the utility. When I connect it to one leg (L1) of my split-phase utility, I have no problem if the neutral is lost — in that case, I simply lose power. However, when I connect it as shown in the image to both L1 and L2 phases of the utility, there is a risk of over-voltage if the neutral connection to the transformer is lost.My question is: assuming I use proper cabling and connectors, is this a risk I need to consider?Is there anything else I might be overlooking that you think I should know?Thank you!
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