When a plumbing or mechanical run requires boring holes in load-bearing wall studs, the code limits bored hole diameter to no more than what fraction of the stud depth for a bearing wall?

Explanation

For bearing wall studs, bored holes may not exceed 40 percent of the stud depth (with stricter limits and reinforcement rules beyond that). 70, 60, and 50 percent all exceed the allowance for bearing studs and would unduly weaken the member. Nonbearing studs allow a larger 60 percent bore.