If you place a Redstone behind a trapped Chest and next to another full powered Redstone source, the Trapped Chest will "cut" the power of the source.
(Sorry if something spelled wrong, I'm learning allday English 🙂 )
Environment
I'm using MagicLauncher with 6144mb(6gig) on a Windows 7 maschine, amd64 and an NVIDIA grafic card. And I use java7
Duplicate of MC-5742.