Note that if a Detector Cable is covered with Construction Foam, it will not output a Redstone signal through the foam.
With conjunction of storage block can be used to detect overflow. Able to handle EU Packets up to 512 with energy loss of 0.5 EU per block.
The Detector Cable can be used as a signal to indicate if a cluster of energy storage blocks are still giving off energy. Combined with the Redstone Lamps from Redpower2, this could be an efficient way of managing your energy stores without needing to physically check every storage unit or having to check the cables with an EU-Meter.