Etho just recently moved one into his base on the crack pack server and it seems to consume any block within a 20 block radius. If you coat it in obsidian you'll prevent it from eating things, but it will still move entities around it.
It should be theoretically possible to put down a wand recharger and a slightly expanded obsidian box that you let specific items through in order to provide the power to the wand. This way a single node could recharge an unlimited number of wands of any size.
Course you'd either have to feed items in by hand, or through trickery.
On the Resonant Rise server that Ako and Saice play on there was someone who made the Hungry node their recharge source. I know Ako showed it in a video, the node was surrounded by Obsidian with only 1 point of access and it had an absolute ton of aspects in it, so they basically plopped their wand into the recharge station and powered it from a single node.