Electrical wiring in a straw bale building. 1/2" and/or 3/4" PVC conduit with non-metal boxes will comply with NEC codes in a residence. NM cable will also comply. Use 1x4 wooden stakes driven into the bales for securing and support. I work as aState Electricla inspector. In 12 years I have only inspected 1 such home. The electrician used steel EMT conduit and 4x4 boxes with switch rings. An electric chain saw works to cut the dados in the bales. If NM cable is used it must be recessed a minimum 1 1/4" from the face of the bales.