NMC in Attic

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Castrovinci

Castrovinci

Member
Location
NJ
All,
My experience lies in Industrial so I have a residential question that I a sure comes second nature for a res guy. If someone can provide some in depth explanation in this I would greatly appriciate it. I am trying to get up more on the residential side and never did any house work, went straight to RMC and 480v side of things.

(2008) 334.23

In Accessible Attics. The installation of cable in
accessible attics or roof spaces shall also comply with
320.23 section A and B as below:

(A) Where Run Across the Top of Floor Joists. Where
run across the top of floor joists, or within 2.1 m (7 ft) of floor or floor joists across the face of rafters or studding, in attics and roof spaces that are accessible, the cable shall be protected by substantial guard strips that are at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 1.8 m (6 ft) of the nearest edge of the scuttle hole or attic entrance.

:-?

I am not completly understanding in what they mean by permanent stairs or ladders. Lets say I have stairs that are connected to an attic door like most that springs down. This is permently attached but not permently down. To me this doesnt seem "permenent". Permenent to me would be stairs like 1st and 2nd floor stairs can someone clarify this more??

Now what do most of you do out there when running new circuits in a new house with an attic door and stairs attached to the door (folds down). Do you run your circuits all the way in the corner across the joists? Just stay 7 feet away? Do you always use a runner anyway? Do you drill out each joist and go across?

Thanks for your help!

Mr Castrovinci
NJ
 
Minuteman

Minuteman

Senior Member
Location
The Sooner Nation
Folding stairs are permanent. I mostly nail to the side of the joist and only drill or install guard strips as required. Whenever possible, I run where the attic height is less than 3' high, just to simplify things.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Minuteman said:
It's funny how that construction practices vary from region to region. For example, the strapping you mentioned in New England. When I watch shows like This Old House, it tickles me how y'all do things up there.
Click to expand...

It would tickle you more if you were an electrician up here because it means you can snake cables either direction.:cool:
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
strapping2.gif
 
kwired

kwired

Electron manager
Location
NE Nebraska
iwire said:
strapping2.gif
Click to expand...
What is the purpose of this strapping? Doesn't appear to serve any structural purpose. Probably is somewhat good deal for electrician but they certainly did not install them just for the electrician. Why not the walls too, there would be a lot less drilling holes for wiring.
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Looks like 2x4 strips (1 1/2") with an octagon of 1 5/8" . That means box extenders...:) or are they using 5/8" rock????
 
L

lakee911

Senior Member
Location
Columbus, OH
Occasionally I do see it on walls. Typically it helps to level and flatten out the ceiling before drywall. I grew up watching TOH and of course I did my own kitchen that way in my 1923 Craftsman. It is really a PITA when you are trying to maximize height and you run into a very low spot.
 
kwired

kwired

Electron manager
Location
NE Nebraska
lakee911 said:
Occasionally I do see it on walls. Typically it helps to level and flatten out the ceiling before drywall. I grew up watching TOH and of course I did my own kitchen that way in my 1923 Craftsman. It is really a PITA when you are trying to maximize height and you run into a very low spot.
Click to expand...

I do see a lot it for leveling a ceiling that is not flat, but for new construction it is absolutely unnecessary. The same ceiling joists are still supporting the ceiling plus the additional weight of the strips. Lateral bracing of ceiling joists is easily done from above with less strips:-?
 
glene77is

glene77is

Senior Member
Location
Memphis, TN
Minuteman said:
Folding stairs are permanent. I mostly nail to the side of the joist and only drill or install guard strips as required. Whenever possible, I run where the attic height is less than 3' high, just to simplify things.
Click to expand...

Was in a house with a 3 foot attic roof height (low roof line),
and,
around the scuttle hole there was the 6 foot distance requirement.

Many of the across the house home-runs
were right over the top of center-line braces, at the 3 foot peak area.

Original Electrician was caught, without a permit, and cited.

(1) Repair required a several hours of pull-out and re-drill and pull-in.
(2) On the across-the-house runs,
some of the center-line braces had 2x4 on top,
which were cut out temporarally,
the between-the-ceiling-joist braces notched 1.5 inches,
cables dropped down to run in the notch,
and the center-line braces reattached with deck screws.

Comments on this method ? :)
 
kwired

kwired

Electron manager
Location
NE Nebraska
iwire said:
You will have to explain that to the local building codes. :grin:
Click to expand...

Just like our trade I'm sure there is a lot of BS in their codes, or at least interpretations of them.

Seen a fire marshal on a new office building project one time require a 1 hour rated door at either end of a stairway (single floor building with unfinished basement, and uncovered wood joist system) to prevent possible fire spread from basement to main floor.

That sounds reasonable but what was not mentioned or required was the fact that there was no covering on the floor joists, just exposed wood joists. I am sure that a fire in the basement was going to spread to main floor through the unprotected floor system much easier than it was going to spread through a stairway with any kind of door installed on it. I would have expected fire rated ceiling covering of some type in basement being more important than the door on the stairway.
 
Minuteman

Minuteman

Senior Member
Location
The Sooner Nation
glene77is said:
Was in a house with a 3 foot attic roof height (low roof line),
and,
around the scuttle hole there was the 6 foot distance requirement.

Many of the across the house home-runs
were right over the top of center-line braces, at the 3 foot peak area.

Original Electrician was caught, without a permit, and cited.

(1) Repair required a several hours of pull-out and re-drill and pull-in.
(2) On the across-the-house runs,
some of the center-line braces had 2x4 on top,
which were cut out temporarally,
the between-the-ceiling-joist braces notched 1.5 inches,
cables dropped down to run in the notch,
and the center-line braces reattached with deck screws.

Comments on this method ? :)
Click to expand...

Ummm? It wasn't me!?! :roll:
 
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