The trick is to either bag the wires before they insulate, ormake the insulators aware that your wires are "NOT" to be affected by their insulation. A good project manager will make this happen if you are aware that foam is going to be used and you raise the concern. all sub trades on a job, especially a high end residential job should co operate and consider each others component. Often times it's not that way on a large commercial project, but again, a good project manager in charge of a small residential build should see that those kinds of things don't happen