Ok, I waited to post this to ensure I would be accurate.  These have been in use since May 2014, on a timer where they come on at 8 pm and go off at 2 am.  I got them to run around the inside perimeter of my tiled porch, solely as a visual aid in checking for rattlesnakes (yes, they love our porch).  The bonus is the lights are soft and make sort of a lovely nightlight effect through our sliding glass doors, and provide sufficient  illumination when family members come home late at night, that they can see to put their key in the lock.  The lights have all stayed on, as near as I can tell, I have had no problems, the setup is 1) timer in wall outlet inside the house; 2) short extension cord from the outlet, out through the dog door, and to the light strand; 3) light strand looping along the walls of the porch.  The package came much more promptly than I expected, and I have had no problems with this product at all.  Oh yeah, there are sticky snake traps under the dog door and the barbecue grill, and these lights help me keep an eye on them, as well!