Application example:

If one wants to add a new receptacle on the second floor in a finished room with no receptacles, the easiest method appears to be doing the wiring in the attic.

However, this would require one to drill one hole through the top plate, in order to get the wire from the desired receptacle location into the attic.

This still beats the only other method to add a new receptacle, which would require one to drill multiple holes in multiple studs, until one reaches the desired receptacle location.


  • How can you determine if a top plate is load-bearing?

  • If it is, what are guidelines to bear in mind, in terms of the location of the hole and the maximum size of the hole that can be drilled, without requiring additional structural blocking?


Don't overthink this.

A reasonably-sized hole for 14 or 12 Gauge 3 or 4 wire cable (i.e. 14-2 with ground up to 12-3 with ground) - or 1/2" EMT in the middle third of the plate will have essentially no effect on the bearing capacity.

| improve this answer | |
  • Must the hole be drilled in the middle third of the top plate? Or, can it be anywhere in the top plate? – Fil Jul 8 '17 at 14:59
  • It should be centered to protect the wiring. Still, you won't cause problems with the occasional hole at any location. – isherwood Jul 8 '17 at 15:20
  • By "middle third", I thought that Ecnerwal was referring to the length of the entire top plate. Was Ecnerwal actually referring to the middle third of the top plate width (the 3½'' dimension)? – Fil Jul 8 '17 at 15:41
  • 1
    I was referring to width. – Ecnerwal Jul 8 '17 at 15:44

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