I think that I would also suggest doubling up on the power supplies, so that each one will only carry about 175 watts. Also fuse the circuits, so that a pinched wire will not take out all the lights. Some 5 amp fuses (assuming 300 watts at 12 volts) would work well for each branch, and then you can have multible circuits, and only 1 will go out at any time.
How did you determine that all of the LED's only consume 280 watts? What if the watt rating on each fixture is off by 5 or 6 watts? You might be overloading the power supply and not know it.
If this is running on DC power, why not try this. Have a battery charger and 12 volt lead acid battery, then install a pair of 250 watt solar panels to make up most of the load. Have the battery charger on a time clock, so that it will not run during daytime hours or about 3 hours after dark. Then the solar panels will charge the battery during the day, as well as light the 300 +/- lights all day long, and into the twilight. After dark, then the battery charger can take over around 7 or 8 pm.
Fred.
