Notching and boring studs to route cable is constrained by the building code rather than the electrical code, because what is at stake is the structural capacity of the framing. Boring a hole near the centre of a member removes material from the least stressed region. Notching removes material from the edge, where the stress is highest, and the limits are correspondingly tighter.
Why the location of removed material matters
A loaded framing member carries its highest stresses at its outer faces, in tension on one side and compression on the other, with a neutral zone near the middle. A hole bored near the centre passes through the region doing the least work. A notch cut into the edge removes material exactly where the fibres are most stressed, and it also creates a stress concentration at the inside corner of the notch, which is where splits start. That is the structural reason boring is preferred, and it is why the permitted notch depth is much smaller than the permitted hole diameter.
The limits come from the building code
Permitted hole diameters and notch depths are specified as fractions of the member width, and they differ between bearing and non-bearing walls, between studs and joists, and for engineered lumber, which frequently has its own manufacturer rules that override the general table. Engineered joists in particular have specific allowable hole zones and sizes published by the manufacturer, and cutting one outside those is a structural defect, not a code technicality. Look up the actual limits for the member you are drilling before making the hole, and treat engineered lumber as requiring the manufacturer document.
Nail plates are the electrical half of the rule
Where a bored hole or a notch leaves the cable close to the face of the framing member, a steel protection plate is required so that a drywall screw or a trim nail cannot reach the cable. The threshold distance is specified in the wiring rules. A notch always requires a plate, because a notched cable sits at the surface by definition. A bored hole near the centre of a stud usually does not, but a hole drilled off-centre or in a narrow member may. Measure rather than assume, and fit the plate before the drywall arrives.
Practical drilling habits
Keep holes at a consistent height so the run is predictable to whoever opens the wall later, and so a whole row can be drilled in one pass. Aim for the centre of the stud width, which both satisfies the structural preference and maximises the distance to the face. Drill a hole large enough that the cable is not forced through, since a tight hole abrades the sheath during the pull and makes future additions impossible. Avoid drilling through the top or bottom plate near the edge, and remember that plumbers and HVAC installers are working in the same cavities.
When a stud cannot be drilled
Sometimes the member is too small, already compromised, or an engineered product with no permissible hole in the location you need. The answer is to route around rather than to cut anyway. Running along the wall in the adjacent cavity, going through the bottom plate into the floor and back up, or using a surface raceway are all legitimate alternatives. Adding blocking or sistering a member to restore capacity is a structural repair with its own requirements and should be treated as such rather than assumed adequate.
What to check before you act
- Look up the permitted hole and notch limits for that specific member.
- Use the manufacturer document for any engineered lumber.
- Fit steel nail plates wherever cable is near the framing face.
- Drill near the centre of the member and keep holes at a consistent height.
Common questions
Can I notch a stud if I add a nail plate?
A plate protects the cable, not the framing. The structural limit on notch depth still applies independently.
Do the same limits apply to a non-bearing partition?
Non-bearing walls generally permit larger holes than bearing walls, but the limits are still specified. Confirm whether the wall is bearing before assuming the looser figure.
The practical takeaway
Bore near the centre, keep within the published limits for that member, and reach for the manufacturer document whenever engineered lumber is involved. Then fit nail plates wherever the cable ends up close to the face.
References and further reading
- NFPA: National Electrical Code overview covering cable protection through framing
- OSHA: Subpart S electrical standards covering wiring methods and protection
- CPSC: home electrical safety guidance including concealed wiring damage
Numerical scenarios are illustrative unless identified otherwise. Follow the exact product instructions; component ratings and local installation requirements can differ.
