I reluctantly had a simular situation... But commercial, and local AHJ demands metallic methods here. (Different story) It had timber and much heavier decking. 4x6 T&G I think... Then a wood floor on that.
300.4(2) Notches in Wood. Where there is no objection because of weakening the building structure, in both exposed and concealed locations, cables or raceways shall be permitted to be laid in notches in wood studs, joists, rafters, or other wood members where the cable or raceway at those points is protected against nails or screws by a steel plate at least 1.6 mm (1/16 in.) thick installed before the building finish is applied.
Exception: Steel plates shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing.
That said, the notch could be 1/2" deep X 5/8" wide (12/2 NM) or big enough for what ever cable you use, and have a 1/16" plate of steel over it. It does not say that it has to be a "Nail-plate" or listed.... Just steel plate.
Structuraly its his house, and aparently edjucated on the damage that he might be under taking with all of this notching? If so, I would tell him, "it's like Pontiac - wider is better, or in this case deeper is better." Then have him steel plate it entirely when it's done....
Mine was a mix of RMC and MC. I used pipe to get more citcuits to areas without haveing to make a whole bunch of notches. And MC jumping point to point. I pre-bent portions of the pipe and traced where I wanted to go. The pipe didn't need protection, and after watching this guy chisle a reccess for the 3/16 X 1 1/2" flat stock to put over the MC, I suggested just using an electric planer, and it worked well. Bottom line I hated doing the job, and I was constantly waiting for some labor/carpenter to butcher me a path, and forcing him to radius bending portions of it. It was irritating! But worked out OK.
If you need to pipe plan out very well. I had to come from walls - 90 onto the floor parralel to the wal, then 90 or kick out away from the wall to keep it flat. This was with 1/2" RMC. Which I preffered, because I have seen EMT squashed before... If you can do it in EMT, you can go to the back side of a 2X wall notched below the bottom plate and not have the radius stick out. It will just barely miss the face of the base trim.
FYI some of the 30/40's Frank Loyd Wright style and some of the Arts and Crafts homes here are done in a mix of pipe and K&T/loom in simular ways. But then short radius benders were still available and legal.
Now.... all that wood, and the guy is opting for Pergo?!
[This message has been edited by e57 (edited 10-03-2006).]