I recently constructed a shelf to have a central location to keep my Surefire collection. It was a cheapish and on sale shelf that uses the wood with that "woodgrain" looking laminated stuff over it. Its not that big, but it has been great and is capable of holding at least a dozen lights as long as they are stored bezel down. I mostly have my C/Z/P pieces with a few e-series as well on it.
The biggest light I have on the shelf is my Z3 that currently has a KT2 Turbohead on it and is sporting a Lumens FactoryIMR-M3T driven by 2X18500 IMR cells... To anyone unfamiliar with this setup, its a high performance incand that gets HOT. And it does it fast. Not just hot like a Triple LED drop in, but actually burn-your-hand-hot within just a few seconds of use. You literally cannot hold your hand over the lens of the light for more than a few seconds after turn on.
Anyway, I really cannot determine how it happened and it is boggling my mind, but I went to climb in bed and turned off the overhead light and in the dark, I just happened to notice an evil glow from my shelf full of lights. I jumped over the bed, freaking out my GF, and started grabbing lights. The Z3 body was hotter than the sun itself, causing me to drop it immediately. I rolled it around on the carpet with my foot to try to keep from melting the carpet as I grabbed a couple of dirty socks to use to grip the light and turn it off. I then unscrewed the tail cap and poured out two incredibly hot IMR cells. Like far too hot to hold IMR cells. The laminated wood grain stuff on the shelves was all bubbled up. I looked the light over and cannot find any damage to it however. I just left the cells to cool on their own and havent put a multimeter to them yet to see if I over-discharged them or not. Probably ruined a set of AW cells. I have no idea of knowing how long that light was on. Im glad I caught it when I did. Possible fire or worse.
The light uses a standard SF Z41 tailcap and I know that before shelving any light, I make a habit of "locking out" those tailcaps. I love the Z41 and have them on pretty much all of my C/Z/P builds as there is pretty much nothing in them to fail. Now, I am guilty of "playing flashlight" sometimes in bed and have been known to lego and swap parts, drop ins, etc while watching TV just for fun. (Who here doesn't do that?) I know though, that I hadn't touched this light though for 4 days. I am having a hard time believing that I would put a light, (especially THAT light) lens down on a shelf with the Z41 tailcap just barely twisted off. I haven't yet had a chance to reassemble and troubleshoot the light and cap, but really, there isnt anything that can fail that would cause the light to just come on.
Im going crazy trying to figure out what happened. Just thought Id share.