Running NM cable through rafters and through floor joists

[ammklq143]

How often does NM cable have to be stapled to the floor joist or rafters in a home when running it perpendicular or diagonal through them, or can the cable just be supported by them without being fastened, since they are only 16 to 24 inches apart?

 

[TobyD]

Through bored hole will be supported and satisfy the requirement.You'll need to staple or by other approved means near your j-box to secure.Along side joists will need to be a maximum of 4'6'' between supports or secured methods.

 

[marti smith]

Keep in mind 334.15.

 

[ammklq143]

Through bored hole will be supported and satisfy the requirement.You'll need to staple or by other approved means near your j-box to secure.Along side joists will need to be a maximum of 4'6'' between supports or secured methods.

Thanks for the info. I'm assuming it still needs to be secured every 4'6" if running perpendicular across the rafters on top of the board, rather than through a bored hole, right?

Thanks.

 

[augie47]

Supposed to be.
At a IAEI meeting a year or so ago, that was listed in the top 5 ignored NEC rules.

 

[John120/240]

If the space between the top of joist & bottom of roof rafter is less than 3 ft

not a problem around here.

 

[renosteinke]

It's worth reminding folks that you ALSO have to comply with the requirements of the structure. Especially with manufactured trusses, boring of holes is something to be done with great caution; They've already 'engineered' every bit of extra wood out of them.

Again, you can find standards for nearly all wood products, available for free, at the Engineered Wood Association, www.apawood.org .

(Imagine that- a trade group that doesn't try to make their fortune as a publishing house!)

 

[construct]

If the space between the top of joist & bottom of roof rafter is less than 3 ft

334.23 requires compliance with 320.23..........320.23(A) requires protection where within 7ft of floor or floor joists. But only if the access is by permanent stairs or ladders. Otherwise, only required within 6ft of the attic entrance.

A good share of residential attics only have a scuttle hole, so....on an inspection I would probably miss that requirement if there were a permanent ladder.:ashamed1: