My community has low voltage (12 volt) lighting that illuminates our entrance signs. It’s 4 – 20 watt halogen bulbs connected to a 300w transformer. There’s a problem that has made them go dim. The setup is relatively simple; a transformer and two pairs of lights wired in parrallel.
Since the installed system uses four 12 volt bulbs that are 20 watts each, I duplicated that setup on a test board. With all four bulbs installed and connected to the transformer, all bulbs light at full brightness when I test at my house. BUT, when I return to the scene of the crime where the transformer is normally plugged in, they glow dimly. In the breaker panel at the problematic location, with no load, I measure 248 volts across the two hot legs and 124 volts from each hot leg to neutral. So far, so good, right? When I add the load, the leg the load is on drops to 63 volts and the other leg goes to 185 volts. If I move the circuit to the other leg, that leg goes to 63v and the opposite leg goes to 185v. In other words the voltage drop follows the load and the opposite leg increases to 185v. I didn’t find any loose connections, but tightenend everything anyway. All of these measurements were made in the breaker panel on both the bus and leads that come in to the main breaker. I didn’t get into the meter. Any thoughts?