NM Protection Between Joist Notches

[tymish]

I have a late 30s house. Last year we had the kitchen and bath remodeled upstairs. In the basement there were old 2 wire AC cables run perpendicularly under the joists going back upstairs. I wasn't there when they replaced the old wire with NM but unfortunately they ran them under the joists again. I wanted them run through joist holes.

Now I'm finishing the basement. Made small notches in the ceiling joists and putting nail plates over the notches. The cable between the joists is very shallow. Does that need to be protected as well? I'll be putting either a 2x 4 or trim board over (under) where the wires are, obviously being very careful to avoid the cables.

(I've tried to get an image up but the links i provide aren't working.)photo

 

[tymish]

BTW I will be installing a surface mount grid ceiling.

 

[mtnelect]

BUILDING CODES

When complying with the National Electrical
Code,® be sure to also comply with the Uniform
Building Code. Building codes are concerned with
the weakening of framing members when drilled or
notched. Meeting the requirements of the NEC® can
be in conflict with building codes. Here is a recap of
some of the key building code requirements that
electricians should be aware of.
Studs:
• Cuts or notches in exterior or bearing partitions
shall not exceed 25 percent of the stud’s width.
• Cuts or notches in nonbearing partitions shall
not exceed 40 percent of the stud’s width.
• Bored or drilled holes in any stud:
– shall not be greater than 40 percent of the
stud’s width, and
– shall not be closer than 5/8 inch to the edge of
the stud, and
– shall not be located in the same section as a
cut or notch.

 

[tymish]

Thanks for the info. I did look that up before notching.

[IRC 502.8] Cutting, Drilling and Notching | UpCodes

Explore a searchable database of US construction and building code. Code regulations are consolidated by state and city for easier navigation.

up.codes

These are 3/4 in deep and 1/2 wide notches in 85 year old 2 x 10 lumber (nominally 1 3/4 by 9 3/4, not like today's 1 1/2) nowhere near the middle third of the span. There are MUCH bigger notches for the original gas lines in worse places LOL.

Mostly concerned about the NM cable between the joists. I'll be putting nail plates over the notches.

 

[Little Bill]

@tymish
Would you please go into your account and update your profile to include your occupation?

 

[AC\DC]

I have wondered about that. From my recollection so don’t quote me,only depth requirements is alleviated by by nail plates, I have wondered about the space between the studs that is still not 1-1/4 from the face of stud. Never had any bark at it though. Never seemed like a good idea.

 

[GoldDigger]

Two factors that I see:
1. By far the most likely place for placing a nail or drill is into the joist, not into the space between them.
2. If, for some reason, you decide to poke something through the ceiling between the joists, you are far less likely to damage the freely moving length of NM than if it were backed up by unyielding wood.
OK, and
3. If you put a 2x4 rather than a trim board over the path of the NM you are just tempting somebody to put a screw into it. Which could be a real problem if the NM is then stapled to the board.
And
4. Just for completeness, the requirement for a cover board shielding NM run perpendicular to basement joists in an unfinished ceiling is supposedly mostly to keep people from trying to hang things from it. Putting in a surface mount grid ceiling serves the same purpose quite well.

 

[Fred B]

2. If, for some reason, you decide to poke something through the ceiling between the joists, you are far less likely to damage the freely moving length of NM than if it were backed up by unyielding wood.

Depends on who is doing it.
Knew a guy that can do it. He hit some MC free floating between 2 ft space of studs, piercing and shorting it out. Did this more than once putting some screws in for sheetrock patch different locations. Got called in after the breaker wouldn't hold. (realize the luck to hit MC in a way to actually pierce a floating MC cable? And then do it more than once.)
Also found several pierced NM during renovations, with the screws still in it, that had been that way for xxx years, these didn't trip any breakers and some were thru the "hot" conductor. Again these were floating in the middle of a stud space, but the point of passing thru the stud was also less than the 1.25" so the wire naturally lay across the space less than the min.
Also came across ones that the screw was acting as part of the conductor passing current for a number of years before a larger than normal current was called for and finally arced out the connection between the screw and wire. NO AFCI present, but have found this several times when AFCI wouldn't hold and eventually found the screw piercing.