To run electric wires through the bales, we made channels in the straw with the back of a hammer, then fastened the wires with large staples made from #7 fencing wire. To fasten the boxes, we made stakes out of 2x4's, pounded them into the wall and screwed the box to the end of the stake. We also used this method to hang kitchen cabinets. The stakes provide a very sturdy platform.