A big pet peeve with me are these Christmas lights that are advertised as not all going out when one bulb fails- HAH Hahahahaha, bastardos! (tormented laugh). Ok, so only half the strand went out. I was hoping that it was a fuse issue as many stands have two circuits with a fuse for each. So I checked the fuses (located in the plug) with a continuity tester, no help, they were good. These look like they are in series and if one half are not illuminated, then the first one should be the culprit, right? Nope, it's good. I refuse to check each bulb. That's why I bought the strand "that stays lite". Therefore I will revert to my original plan of tossing a strand and replacing it when it acts up. My particular brand is Philips 100 lights strand of Mini Lights. It's not like they are expensive $4.99 each so it's not that much of a hardship, but still highly annoying! Note: "Set stays lit if one bulb burns out." Liars!