I am trying to flush-mount a structured wiring cabinet in a non-load-bearing closet wall (nothing above it but a truss attic). The wall is a staggered stud wall, with each row of studs 16" o.c. and the rows offset 8" o.c. from one another. The plates are 2x6. I don't know if the fact that it is a staggered stud wall impacts the answer or not, but including that info for completeness.
The cabinet will fit nicely between the 16" o.c. studs, but the staggered studs in the middle of each stud bay do not give me the depth needed for it to sit flush with the drywall. I need to notch the rear stud by 1 3/8". Since this is not a load-bearing wall, I believe this is code compliant (less than 40% of the actual width of the stud).
My question: Is there a limit to the length of the notch (which would be ~42" in this case), or does length not matter because the effective width of the stud has been reduced by making the notch, regardless of its length?
Update: After removing more of the insulation I discovered a single electrical cable going through a hole in the rear stud (but behind the front studs). I can't notch it in the same cross section as the hole, right? Or does that not apply here due to it beyond a staggered stud wall with two un-notched 16" o.c. studs on either side of it? Can I fill the hole with a dowel before notching?