A few years ago when doing some remodeling in another area of the house I had the state electrical inspector in. In passing through he noted that my outlets shown in the pictures below "can't be mounted directly to block. Need to be mounted to a board like plywood". He didn't elaborate any further.
I need to clean a few things up in a small area of the basement and add a couple outlets. What is the correct way to do this? Is the plywood part of code to secure the wiring, or what's wrong with the boxes?
2 examples, metal conduit boxes in both pics, screwed to block:
washer/dryer
furnace shutoff
