Nail Plates and Protecting What Runs Through Studs

Why this matters

A cable or pipe bored through a stud is safe from everything except the next trade. The drywaller's screw, the cabinet installer's 3 in screw through the hanging rail, the trim carpenter's nail and the homeowner's picture hook all go into the face of that stud, and the codes assume they will. A screw through a cable is a fault that may not show for months: it can sit as a high-resistance contact that heats, or short when the wall moves. A screw through a PEX line leaks inside a finished wall until the ceiling below stains. The steel plate over the bored hole is a few seconds of work at rough-in and the only protection the wall gets after it is closed.

The electrical rule: 1-1/4 in or a plate

The National Electrical Code, as adopted by your jurisdiction, sets the distance in 300.4(A). The section number has been stable across recent editions, so the citation travels.

• Bored holes in wood members. Where a cable or raceway-type wiring runs through a bored hole in a stud, joist or rafter, the edge of the hole must be at least 1-1/4 in from the nearest edge of the member. Where it is closer, the cable or raceway must be protected by a steel plate or bushing at least 1/16 in thick, long and wide enough to cover the area of the wiring. Recent editions also permit a listed and marked plate thinner than 1/16 in that gives equal or better protection against nail and screw penetration.
• Notches in wood members. Where the wiring lies in a notch, it gets a 1/16 in steel plate over the notch regardless of depth, and the notch itself is limited by the framing rules. See related: Notching and Boring Limits in Wood Framing.
• Running along a member. Cables run parallel to a stud or joist must also sit 1-1/4 in back from the nearest edge where nails or screws are likely, or be protected the same way (300.4(D)).
• Exceptions that matter in the field. Rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit and EMT do not need the plate (300.4(A)(1), Exception No. 1). Nonmetallic sheathed cable in a hole does.

Two neighboring rules a remodeler meets: cables run under metal-corrugated roof decking must be at least 1-1/2 in from the deck's lowest surface (300.4(E)), and cables through holes punched in steel studs need bushings or grommets, with steel protection where screws are likely. See related: Steel Studs and Cutting Into Them.

The plumbing and gas rule: 1-1/2 in, and the plate is longer

The plumbing codes protect pipes the same way, with a different number. In the 2021 edition of the International Residential Code, P2603.2.1 (and IPC 305.6 in the commercial code, in the 2021 edition), as adopted by your jurisdiction:

• Pipe other than cast iron or galvanized steel, run through holes or notches in studs, joists, rafters or similar members, gets a shield plate where the pipe is less than 1-1/2 in from the nearest edge of the member.
• The plate is at least 0.0575 in thick steel (No. 16 gage), covers the area of the pipe where the member is bored or notched, and extends at least 2 in above sole plates and below top plates.

Fuel gas piping has its own version in the fuel gas provisions (IRC G2415.7 and IFGC 404.7 in recent editions), with the plate extending past the member on each side, and corrugated stainless steel tubing carries its manufacturer's own striker-plate requirements on top of the code. Read both; the installation instructions are part of the listing.

The Uniform Plumbing Code, adopted in several Western states, words its protection rule differently. If your state uses it, read its section rather than this one.

Same hole, different answer

The two codes measure against different numbers, so a hole that passes for a cable can fail for a pipe. This is the most common place a careful installer gets it wrong.

  2x4 stud seen end-on, 3-1/2 in deep

  face A                            face B
    |                                 |
    |<-1-1/4->(  1 in hole  )<-1-1/4->|
    |                                 |
    |<---- 3-1/2 in stud depth ------>|

  centered 1 in hole:    1-1/4 in to each face
  cable, NEC 300.4(A):   1-1/4 in or more -> passes
  pipe, IRC P2603.2.1:   1-1/2 in or more -> plate

On a 2x4, (3.5 minus 1.0) divided by 2 leaves exactly 1-1/4 in to each face. The cable passes with nothing to spare; the pipe in the same hole fails by 1/4 in and gets a plate on both faces. To pass the plumbing rule in a 2x4, a centered hole would have to be no more than 1/2 in in diameter ((3.5 minus 0.5) divided by 2 is 1.5), which no supply line fits through. In practice, every pipe through a 2x4 gets plates on both sides, and on a 2x6 (5-1/2 in deep) a centered 1 in hole leaves 2-1/4 in to each face and needs none.

A hole drilled off-center is where cables fail. A 3/4 in hole drilled 1 in back from one face leaves 1 in on that side: plate required on that face, even though the cable is "inside the stud".

The code distance assumes a drywall screw, not a cabinet screw

The 1-1/4 in figure is generous against a drywall fastener. A 1-1/4 in screw through 1/2 in drywall reaches 3/4 in into the stud; a 1-5/8 in screw through 5/8 in drywall reaches 1 in. Both stop short of a cable that sits 1-1/4 in back.

Cabinets are different. Upper cabinets are hung with screws of 2-1/2 to 3 in through a 3/4 in hanging rail and the drywall. A 3 in screw through 3/4 in rail and 1/2 in drywall reaches 1-3/4 in into the stud, and past the 1-1/4 in clearance by 1/2 in. A screw through a tub surround, a grab bar flange or a closet shelf cleat can do the same. That is why the plate matters even where the code distance is met on paper, and why the walls that get cabinets, a vanity or a grab bar are the walls to plate generously: a plate is required at less than the code distance and is never wrong at more.

Worked example: the plumbing wall behind a new kitchen

A remodel crew opens a kitchen to bare studs. The plumber runs 1/2 in PEX hot and cold to a new sink location through 1 in holes centered in 2x4 studs, at about 20 in above the floor, through five studs. The electrician runs a 20 A small-appliance circuit through 3/4 in holes at about 44 in above the floor, over the counter, through the same five studs, centered.

Electrical check. A centered 3/4 in hole in a 2x4 leaves (3.5 minus 0.75) divided by 2, which is 1-3/8 in, to each face. That is more than 1-1/4 in, so 300.4(A)(1) needs no plate. But the cable sits at 44 in, just above a 36 in counter, which is exactly where a backsplash box, a pot-filler bracket or a shelf cleat gets fastened later. The electrician plates all five holes on the room face anyway. That is above the code minimum and costs a box of plates.

Plumbing check. A centered 1 in hole leaves 1-1/4 in, under the 1-1/2 in the plumbing code requires, so every one of the five studs gets a shield plate on each face where the PEX passes. Where the PEX turns up through the bottom plate into the sink cabinet, a centered 1 in hole in the 3-1/2 in bottom plate is also under 1-1/2 in from each wall face, so a shield goes on each face there and extends 2 in above the bottom plate.

Count. Five studs times two faces is ten plates for the plumbing run, plus two at the bottom plate, twelve in all; five more on the room face for the cable makes seventeen. The rough-in inspector checks for them before insulation and drywall go on, and that is the point at which they are cheap.

What would have changed the answer. On 2x6 studs, the 1 in PEX holes centered leave 2-1/4 in to each face and pass both codes with no plate; the electrician's plates would still be a good idea on the cabinet wall but no code would require them. If the electrician had run the cable in EMT instead of cable, the conduit exception removes the plate requirement for the wiring.

When the drywaller or the cabinet installer finds one missing

The wall is open, the drywaller is hanging board, and there is a bored hole with a cable or pipe in it and no plate. What happens next depends on who is looking.

• The drywaller should stop fastening at that stud and flag it to the general contractor or the owner, not guess. Hanging over it and screwing a few inches to one side is the common shortcut and it relies on everyone after the drywaller knowing where the gap is.
• Adding a plate is quick and normally within anyone's reach, but on a permitted job it is the responsible trade's correction, and the inspector may want to see it. If the cover inspection has already passed, the plate goes on anyway; the inspection approved what was visible, not the absence of a plate.
• The cabinet installer finds it differently: the screw goes in hard, then soft, or the drill bit comes back with copper or plastic shavings, or water appears. Stop, back the screw out only if it is not holding back water (a screw sitting in a pierced pipe is often the only thing slowing the leak), shut the water at the fixture valve or main, and call the plumber. With a cable, do not back it out with the circuit on: shut off the breaker for that circuit and prove it dead with a tester checked on a known live source before and after, before touching the screw, then call the electrician. A screw through a cable means the cable is repaired or replaced, not taped.
• Tell the customer and record it. A missing plate that one trade found and quietly worked around is a missing plate for every trade after it.

Who pays for the damage when the plate was missing is a contract and insurance question between the trades and the owner. This is not legal advice; walk into that conversation with photos of the open wall, the hole location measured from the stud face, and who was on site when.

How to verify the wall is protected before it closes

Before insulation and board go on: every bored or notched member with wiring closer than 1-1/4 in to a face has a plate on that face; every pipe closer than 1-1/2 in has a 16 gage plate extending 2 in past top and bottom plates; gas piping and corrugated tubing carry the plate the fuel gas code and the manufacturer require; and the walls that will get cabinets, vanities, grab bars or wall-hung equipment are plated even where the distance is met. Photograph each wall with a tape in the frame; that photo answers every later question about what was in the wall.

References

• NFPA 70, National Electrical Code, 300.4, as adopted by your jurisdiction
• International Residential Code 2021, P2603.2.1 and G2415.7; International Plumbing Code 2021, 305.6; International Fuel Gas Code, 404.7; as adopted
• Corrugated stainless steel tubing manufacturer installation instructions
• See related: Notching and Boring Limits in Wood Framing
• See related: How to Scan a Wall Before You Cut or Drill