Hi, I have a beginners question. I am replacing some old single pole 15A switches and a dimmer, with some newer decorator switches and dimmer. The one difference noticed to the new units is that they all have a green ground screw, when the current ones installed do not have. Inside my wall I see 3 bare copper attached, so do I need to do a pig tail from each new switch to the existing bare copper or may I ignore the green ground screw? [ATTACH]49860[/ATTACH]

yesterday I replaced an outdoor light that was for the backdoor to my garage with an LED motion light. I bought one of those defiant brands at home depot, the one with the "plug in" wiring kind. I did not care for this plug in as it was a bit difficult to get it to set in place when I put the light onto the mount and made it difficult to tell if you had a solid connection. In any case, I got it installed ok and waited for it to get dark to test it out. Note that the circuit is from the sub panel in the garage (15 amp circuit) and is controlled by a 2 way switch. Anyways, when I went into the garage last night the first thing I noticed is that when I turned on the garage lights, they flickered. They would stop after a few seconds though. I went over to the new motion light and confirmed that the switch was "on", so I then confirmed the motion light worked, and it did. So I shut off the garage lights and turned them back on and once again they flickered. Suspecting the new light fixture, I shut off the 2 way switch that controls that, then again shut off the garage lights and turned them back on. They still flickered for a few seconds. At this point my son came into the garage and said the TV in the LR had gone off, and I went into the house at the main panel and found that the breaker controlling the outlets in the LR had tripped. It was a 20 amp breaker, one of AFCI breakers with a fault light on it. I reset it, went back outside and turned on the motion light, and the same breaker in the house tripped. I immediately disconnected the light fixture from its built in plug on the mount, and at that point I could turn on the garage lights without flickering. So I suspected either a faulty fixture, or more likely, that built in plug was not getting a nice tight connection, as its near impossible to tell as you have to fiddle around with it trying to blindly set it in while at the same time lining up the mounting holes. At this point I just wanted to return the light and get the old style kind where I wire nut together the connections, but as I was picking up, I noticed a burning smell at the electrical sub panel in the garage. The lights in the garage still worked, so the breaker was not toasted, but I obviously fear something sustained damage in that panel. I see nothing visibly burnt. Can a breaker put off that smell even if its still working? I could replace it myself, or I could bring in an electrician to take a closer inspection I guess. There are only a couple of breakers on the sub panel, so it would be no big deal to replace them. My bigger concern is why would that trip a specific breaker inside the house that is off the main panel? I did not observe any burning smell off the main panel, thankfully. do I have reason for concern here or would just having a less than solid connection at the light fixture cause all this?